# The EUV reflectance of Mercury's surface measured by BepiColombo/PHEBUS

Jean-Yves Chaufray, Eric Quémerais, Dimitra Koutroumpa, Rozenn Robidel, François Leblanc, Aurélie Reberac, I. Yoshikawa, K. Yoshioka, G. Murakami, O. Korablev, et al.

► To cite this version:

Jean-Yves Chaufray, Eric Quémerais, Dimitra Koutroumpa, Rozenn Robidel, François Leblanc, et al. The EUV reflectance of Mercury's surface measured by BepiColombo/PHEBUS. Journal of Geophysical Research. Planets, 2023, 128 (3), pp.e2022JE007669. 10.1029/2022JE007669. insu-04022685

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<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
**Key Points:**

* We derive the reflectance of Mercury's surface between 90 and 160 nm for the first time since Mariner 10

* The lower albedo of Mercury compared to the Moon could be due to a lower FeO concentration but other opaque species may be needed

* Some spectral variations could possibly be due to SiO₂

**Correspondence to:**

J.-Y. Chaufray,
jean-yves.chaufray@latmos.ipsl.fr

**Citation:**

Chaufray, J.-Y., Quémerais, E., Koutroumpa, D., Robidel, R., Leblanc, F., Réberac, A., et al. (2023). The EUV reflectance of Mercury's surface measured by BepiColombo/PHEBUS. *Journal of Geophysical Research: Planets*, 128, e2022JE007669. https://doi.org/10.1029/2022JE007669

Received 17 NOV 2022

Accepted 28 FEB 2023

<figure><img src="image_2.png" /></figure>

# The EUV Reflectance of Mercury's Surface Measured by BepiColombo/PHEBUS

J.-Y. Chaufray<fnref n="1" /> ID, E. Quémerais<fnref n="1" /> ID, D. Koutroumpa<fnref n="1" /> ID, R. Robidel<fnref n="1" />, F. Leblanc<fnref n="1" /> ID, A. Réberac<fnref n="1" />, I. Yoshikawa² ID, K. Yoshioka² ID, G. Murakami<fnref n="3" /> ID, O. Korablev⁴ ID, D. Belyaev⁴ ID, M. G. Pelizzo⁵, and A. J. Corso⁶

**Abstract** On 9 and 10 October 2021, Probing the Hermean Exosphere by Ultraviolet Spectroscopy aboard BepiColombo observed the disk-integrated reflected light from the Sun by Mercury in the spectral range 90–160 nm at a phase angle of 70°. These observations are used to derive the EUV reflectance of the surface of Mercury in this wavelength range for the first time since the Mariner 10 observations in 1974–1975. Our observations are in agreement with a surface of Mercury darker by a factor ~0.5–0.6 compared to the Moon in this wavelength range, with an average reflectance of 0.3% at a phase angle of 70°. This lower reflectance of Mercury could be due to the lower abundance of FeO. The derived reflectance near 160 nm is close to the derived reflectance at 220 nm by MESSENGER/MASCS at a similar phase angle. Possible spectral variations measured between 110 and 140 nm could be attributed to SiO₂ glass, but the signal to noise ratio is low and other observations, possible at several periods during the rest of the cruise, are needed to confirm this last result.

**Plain Language Summary** Due to the lack of atmosphere, the solar UV radiation directly impacts the surface of Mercury. A fraction of this radiation is reflected into space in all directions. This reflected fraction varies with wavelength and can be analyzed to constrain the composition and texture of the surface of Mercury. Probing the Hermean Exosphere by Ultraviolet Spectroscopy aboard BepiColombo observed the reflected radiation between 90 and 160 nm for the first time since the Mariner 10 observations in 1974–1975. In this study, we measure the fraction of UV radiation reflected at different wavelengths. We compare our results with past observations from Mariner 10. We explain part of the observed spectral variations as possible due to the presence of SiO₂ glass at the surface of Mercury and an albedo lower than the Moon due to a lower abundance of FeO.

## 1. Introduction

Spectral reflectance is a useful tool to investigate the composition of planetary surfaces. On the Moon, several variables affect the reflectance of surface including the amount of oxidation state of iron or titanium in silicates and oxides, the presence of opaque minerals such as ilmenite and carbon-bearing phases, and the degree of space weathering (e.g., Murchie et al., 2018). The presence of ferrous iron in minerals is responsible for an absorption band at ~1 µm wavelength detected at the surface of the Moon (e.g., Hapke, 1977). On Mercury, this feature was not detected by Mariner 10 (Hapke, 1977), suggesting a lower abundance of ferrous oxides on Mercury than on the Moon. The lack of absorption band near ~1 µm was confirmed by the observations performed by MESSENGER/MASCS (Izenberg et al., 2014; McClintock et al., 2008). This lack of detection has been used to estimate the fraction of FeO on Mercury with current estimate varying between (1%–5%) in agreement with the global range of ~1%–2% and 1.3%–2.6% derived from MESSENGER's X-Ray Spectrometer (XRS) and Gamma-Ray Spectrometer (GRS) respectively (Domingue et al., 2014; Izenberg et al., 2014; Murchie et al., 2018; Vilas et al., 2016). The lower fraction of FeO on Mercury than on the Moon (varying between 3% at Tycho crater to 23% in the western mare regions Lawrence et al., 2002) is consistent with the reflectance shortward 200 nm of Mercury approximately ~2/3 that of the Moon, derived by Mariner 10 (Hapke, 1977; Wu & Broadfoot, 1977). New UV measurements could provide new constrains on the FeO fraction at the surface of Mercury, even if a detailed quantification of the effect of FeO on the EUV albedo is still missing.

<footnote n="1">¹LATMOS-IPSL, CNRS, UVSQ, Paris-Saclay, Sorbonne Université, Guyancourt, France, ²Tokyo University, Tokyo, Japan,</footnote>

<footnote n="3">³Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan, ⁴IKI, Moscow,</footnote>

<footnote>Russia, ⁵Department of Information Engineering, University of Padova, Padova, Italy, ⁶National Research Council of Italy,</footnote>

<footnote>Institute for Photonics and Nanotechnologies, Padova, Italy</footnote>
The UV reflectance of several airless bodies of the solar system has also been studied, showing the effect of the presence of ices on the Far-UV (FUV) reflectance (Gladstone et al., 2012; Hendrix et al., 2018) as well as the differences between fresh material and mature material of the same composition (Hendrix & Vilas, 2006; Hendrix, Retherford, et al., 2012), or specific regions like the swirls on the Moon (Hendrix et al., 2016). Sunlight can be scattered by two processes from a grain: reflection from the surface (Fresnel reflection) and volume scattering of rays which have been refracted into its interior (Hapke, 1981). At UV wavelengths, surface scattering can dominate because the grain size is typically much larger than the wavelength and the absorption increases toward shorter wavelengths (e.g., Hendrix & Vilas, 2006). Measuring the UV reflectance of a surface can then be used to provide constraints on the refractive index of the surface of the grains, considering, for example, a parametrized model of the bidirectional-reflectance (e.g., Hapke, 2001).

Remote observations are divided into two categories: disk-integrated and disk-resolved measurements (Domingue et al., 2010). Disk-integrated observations, studied in this paper, are a measure of the entire disk (disk-integrated reflectance) of Mercury. The disk-integrated reflectance depends on the solar phase angle $g$: the angle between the Sun-Mercury and Mercury-Observer directions (Hapke, 2012). Disk-integrated observations of Mercury have been conducted from Earth in the visible domain before the first flyby by Mariner 10 (Danjon, 1949; Irvine et al., 1968). Since these historical observations, disk-integrated observations of Mercury have been performed using Mariner 10 (see Cremonese et al., 2007 for a summary), SOHO (Mallama et al., 2002), and MESSENGER (Domingue et al., 2010; Holsclaw et al., 2010; McClintock et al., 2008). Mariner 10 observed the reflected solar flux at several wavelengths (58.4, 74, 86.7, 104.8, 121.6, 130.4, 148.0 and 165.7 nm) during the three flybys of Mercury (Wu & Broadfoot, 1977). A theoretical photometric function from Hapke (1966) was used to derive the physical (or geometric) albedo (i.e., the disk-integrated reflectance at 0° phase angle). The derived values were uncertain but found between 1%–4% with a general decrease from 58.4 to 165.7 nm.

MESSENGER observed the reflected solar flux longward of 200 nm (Domingue et al., 2010; Holsclaw et al., 2010; McClintock et al., 2008). The disk-integrated reflectance measured at phase angles of 75°, 86°, and 90° shows an increase of the reflectance from 220 to 300 nm by a factor of ~3, larger than that of the Moon, without specific noticeable absorption feature (Holsclaw et al., 2010; McClintock et al., 2008).

In this study, we present new measurements of Mercury's reflectance acquired by Probing of Hermean Exosphere by Ultraviolet Spectroscopy (PHEBUS) (Chassefière et al., 2010; Quémerais et al., 2020) using the EUV channel (~55–160 nm). The observations are presented in Section 2, the derived reflectance is presented in Section 3 and discussed in Section 4, followed by a conclusion in Section 5.

## 2. Methods

### 2.1. Observations

#### 2.1.1. Instrumental Description

The PHEBUS instrument is a multiple channel instrument composed of two spectrographs operating in overlapping spectral ranges in the ultraviolet (EUV channel: 55–155 nm and FUV channel: 145–320 nm) and two additional band-integrating channels that capture emissions at 404 and 422 nm from potassium and calcium, respectively. The instrument and its scientific goals are described in detail in Chassefière et al. (2010) and Quémerais et al. (2020). Due to instrument functional constraints, only one of the 2 UV channels can be operated during one observation. The high-voltage of one channel needs to be ramped up before the measurements and then it is not possible to use a duty-cycle for two channels every 10 s. The two visible detectors can be activated along with the selected UV channel. Photons from the observed source pass through a rotating entrance baffle and reach the primary mirror. This rotating mechanism allows changing the pointing direction of the PHEBUS field of view (FOV). After reflection by the primary mirror, photons are focused on a removable rectangular slit (5.6 mm × 0.28 mm) placed at the focal plane (focal length = 170 mm) of the mirror (Quémerais et al., 2020) and reach one of the two holographic gratings (EUV and FUV). No imaging capability along the slit is possible. When the slit is removed, the projected field of PHEBUS is defined by the “pre-slit,” which is the exit pupil of the scanner mechanism.

The EUV and FUV detectors are positioned along the focal planes of the gratings. In the UV ranges, the spectrum acquisition is accomplished by photon counting, detection is realized using a microchannel plate (MCP) with
<table><caption>**Table 1**

Geometric Parameter of the Six Observations of Mercury Done by Probing the Hermean Exosphere by Ultraviolet Spectroscopy</caption><thead><tr><th>Sequence</th><th>Observation number</th><th>Date</th><th>D (AU)</th><th>Δ (AU)</th><th>Phase angle (degree)</th><th>Ω<sub>mercury</sub> (str)</th><th>Scan angle</th></tr></thead><tbody><tr><td rowspan="3">1</td><td>1</td><td>9 October 2021, 01:30:02–01:46:01</td><td>0.341</td><td>0.0271</td><td>68.2</td><td>1.13 × 10<sup>-6</sup></td><td>39.5°</td></tr><tr><td>2</td><td>9 October 2021, 01:48:32–02:04:31</td><td>0.341</td><td>0.0271</td><td>68.2</td><td>1.13 × 10<sup>-6</sup></td><td>38.5°</td></tr><tr><td>3</td><td>9 October 2021, 02:07:01–02:23:00</td><td>0.341</td><td>0.0272</td><td>68.3</td><td>1.13 × 10<sup>-6</sup></td><td>40.5°</td></tr><tr><td rowspan="3">2</td><td>4</td><td>9 October 2021, 23:30:02–23:46:01</td><td>0.336</td><td>0.0304</td><td>71.8</td><td>9.04 × 10<sup>-7</sup></td><td>160°</td></tr><tr><td>5</td><td>9 October 2021, 23:48:32–00:04:31</td><td>0.336</td><td>0.0304</td><td>71.8</td><td>9.04 × 10<sup>-7</sup></td><td>159°</td></tr><tr><td>6</td><td>10 October 2021, 00:07:01–00:23:00</td><td>0.336</td><td>0.0305</td><td>71.9</td><td>9.04 × 10<sup>-7</sup></td><td>161°</td></tr></tbody></table>

Note. D is the Sun-Mercury distance, Δ the BepiColombo-Mercury distance and Ω<sub>mercury</sub> the solid angle of Mercury seen from BepiColombo.

Resistive Anode Encoder (RAE). In this manuscript, one observation will be defined as the measurements done continuously at one given scan angle.

### 2.1.2. Observations

Six observations using the EUV spectrograph were performed by PHEBUS on 9 and 10 October 2021 during two sequences. The first sequence was done on 9 October 2021 from 01:30 to 02:23 UT, using three different scan angles of PHEBUS equal to 39.5, 38.5 and 40.5° from the parking position (position of the instrument when it is not operating, see Quémerais et al., 2020 for details). This set of angles was selected to maximize the probability to have Mercury in the FOV of PHEBUS for at least one observation. The second sequence was done from 9 October 2021 23:30 to 10 October 00:23 using again three different scan angles (160°, 159°, 161°). The geometric parameters for each observation are given in Table 1. All the observations were performed without the slit, corresponding to an entrance FOV of 4.088 square degree (1.2 × 10<sup>-3</sup> str), much larger than the size of Mercury seen from BepiColombo. For all these observations, Mercury can be considered as a point source. Possible small radiometric sensitivity of a few % with the scan angle is considered as part of a systematic uncertainty.

Mercury was detected during the six observations. Attempts to observe Mercury with the FUV detector during this period failed because of the use of nonoptimal detector parameters.

The 16 min-integrated images of the detector for each observation are shown in Figure 1.

The solar reflected light by the Mercury surface corresponds to the horizontal line near the center of the images. The different positions and inclinations of this horizontal line from one image to another are a consequence of the different positions of Mercury in the PHEBUS FOV. The signal is spread over horizontal rows 110–150. Above and below, only dark counts are observed (Quémerais et al., 2020).

<figure><img src="image_3.png" /><figcaption>**Figure 1.** Images of the average count rate on the detector for the six observations. The spectral axis is the horizontal axis (the wavelength increases from left to right). The spectra are the sum of the reflected solar light by Mercury (bright nearly horizontal line in the middle of the image), the interplanetary medium (extended vertically spots with helium emission near column pixel 80 and Lyman-α near column pixel 320) and dark current. The two blue bended lines at the bottom and the top of each image are instrumental artifacts. The line spread function is not uniform and decreases with the wavelength. The maximum value is ~1.65 count/px/s.</figcaption></figure>
<figure><img src="image_4.png" /><figcaption>**Figure 2.** Example of Lyman-$\alpha$ emission during the Mercury's observation by the Probing the Hermean Exosphere by Ultraviolet Spectroscopy (a cut along the line 130 for observation 1 in black) and a fit of the interplanetary emission derived from sky observations (blue line). The vertical dashed lines indicate the pixel position of the observed solar emission lines at Lyman-$\gamma$, Lyman-$\beta$ and Lyman-$\alpha$ used for wavelength calibration.</figcaption></figure>

The interplanetary medium is populated by hydrogen and helium atoms able to resonantly scatter the solar He and H UV emission lines in all directions (e.g., Quémerais et al., 2013) and then in the PHEBUS FOV. The bright- est signal in the images corresponds to the Lyman-$\alpha$ emission of the inter- planetary medium (121.6 nm), which is spectrally and spatially broader than Mercury's reflected spectral component, because the interplanetary source fully covers the PHEBUS FOV, while Mercury can be considered as a point source. The other large spot near column pixel = 80 corresponds to the inter- planetary emission of helium (58.4 nm). The width of the Point Spread Func- tion (PSF) is not constant along the spectral axis (in Figure 1) and its standard deviation varies from ~1 pixel near 160 nm (column ~450) to ~4 pixels near 90 nm (column ~200) for all observations.

The Lyman-$\alpha$ emission of the Sun reflected by the surface of Mercury is seen on all images by the small red spot, aligned with the solar reflected spectrum, which is less extended horizontally and vertically than the interplanetary emission. While the positions of the interplanetary emission are fixed in the images, the position of the solar Lyman-$\alpha$ emission reflected by Mercury is shifted horizontally and vertically from one image to another. For example, on observation four it appears slightly near the center of the interplanetary emission, while for other observations it is on the left. Since the wavelength

of this emission is constant (121.6 nm), the pixel—wavelength calibration of the reflected solar spectrum differs from image to image. The signature of the reflected solar spectrum is visible from column pixels ~165 to 470 (~80–160 nm). We will then consider only this spectral range. A derivation of the Mercury's albedo at 58.4 nm requires additional observations (scheduled during the rest of the cruise).

## 2.2. Interplanetary Medium Correction and Spectral Calibration

To isolate the reflected solar radiation at Lyman-$\alpha$, we need to subtract the interplanetary Lyman-$\alpha$ contribution. During the cruise, few observations of the interplanetary emissions have been performed with and without the slit. Without the slit, the shape of the emission line is stable with time. Then, an interplanetary spectrum observed during the cruise, without Mercury, has been rescaled to fit the observed interplanetary emission of each obser- vation with Mercury (Figure 2) This interplanetary emission (~0.4 count/s/px) and a dark background estimate (~2 × 10⁻³ count/s/px) are subtracted from all datasets.

The rows of the detectors where the reflected solar spectrum is observed (Figure 1) are used to generate an aver- age spectrum per observation. The number of rows added is not constant due to the nonuniformity of the PSF. The number of rows added vary from ~5 near 160 nm to ~15 rows near 90 nm. In the following section, we will call a “bin” the number of pixels in the spatial direction summed to generate the average spectrum. A bin is then a detector surface of width 1 pixel and length varying from 5 to 15 pixels.

Several emission lines are visible in the observed reflected spectrum, for example, at Lyman-$\alpha$ (121.6 nm), Lyman-$\beta$ (102.5 nm), Lyman-$\gamma$ (97.2 nm), O (130.4 nm), C⁺ (133.5 nm), and Si³⁺ doublet (140 nm). These emission lines are used to calibrate the wavelengths of each spectrum. The three average spectra of each sequence (colored lines in Figure 3) are then summed to derive an average spectrum per sequence (black line in Figure 3).

The count rate of the first sequence is expected to be larger due to the closer distance of BepiColombo to Mercury (Table 1) and therefore, the final spectrum is calculated from the two average spectra weighted by the rela- tive geometric factor $\Omega/D^2$ (see Section 3). The final representative spectrum of the full set of observations is compared to the composite Whole Heliosphere Irradiance (WHI) solar spectrum from 25 to 29 March (Woods et al., 2009) (Figure 4) and used to derive the reflectance.

## 3. Results: UV Reflectance

The observed spectra presented below are not spatially resolved and correspond to disk-integrated spectra. There- fore, all the parameters studied in this manuscript correspond to disk-integrated parameters, and hereafter the term «disk-integrated» will be omitted.
<figure><img src="image_5.png" /><figcaption>**Figure 3.** (Left panel) Average spectra derived for the three observations of the first sequence (colors) and the average spectrum (black). (Right panel) Average spectra for the three observations of the second sequence (colors) and the average spectrum (black). The positions of the main solar emission lines indicated by the vertical solid lines at 97.2 nm (H Lyman-γ), 102.5 nm (H Lyman-β), 121.6 nm (H Lyman-α), 130.4 nm (O I), 133.5 nm (C⁺) and the doublet near 140 nm (Si³⁺) have been used to calibrate the wavelength of each spectrum.</figcaption></figure>

The disk-integrated reflectance *I/F* is the ratio of the radiance from the hemisphere of a planet viewed by an observer *I* to the radiance expected from a perfect Lambertian surface normally illuminated by the Sun *F*. Using the notation of Hapke (2012), we have the following equation:

$$[I/F](\lambda, g) = \frac{\int_A J(\lambda)r(i, e, g, \lambda) \frac{\mu dA}{\pi R^2}}{\frac{J(\lambda)}{\pi}} = A_p(\lambda)\Phi_p(\lambda, g) \quad (1)$$

where, *J*(*λ*) is the solar spectral irradiance at the body (power per unit area per unit wavelength), *r*(*i*, *e*, *g*, *λ*) is the bidirectional reflectance of the elementary surface *dA* (illuminated and visible by the observer) of the body at incident angle *i*, emission angle *e* (*μ* = cos(*e*)), phase angle *g* and wavelength *λ*. *R* is the radius of the spherical body. It can also be expressed as the product of the physical (or geometric) albedo *A*<sub>p</sub>(*λ*) and the integral phase function *Φ*<sub>p</sub>(*λ*, *g*) (Hapke, 2012, Equations 11.30 and 11.35). The reflectance at *g* = 0° is equal to the physical albedo because *Φ*<sub>p</sub>(*λ*, 0°) = 1.

The spectral irradiance *E*<sub>p</sub>(*λ*, *g*) at the entrance of an instrument (power per unit area) is given by the following equation:

$$E_p(\lambda, g) = \frac{\omega}{S_p} \int_A J(\lambda) r(i, e, g, \lambda) \mu dA \quad (2)$$

where *ω* is the solid angle of the instrument surface entrance as seen from the body and *S*<sub>p</sub> is the entrance pupil of the instrument. *ω* ~ *S*<sub>p</sub>/Δ<sup>2</sup>, where Δ is the observer-body distance, so:

$$E_p(\lambda, g) = \frac{1}{\Delta^2} \int_A J(\lambda) r(i, e, g, \lambda) \mu dA \quad (3)$$

Then, the disk-integrated *I/F* can be related to *E*<sub>p</sub> (Domingue et al., 2010; Holsclaw et al., 2010) by the following equation:

$$[I/F](\lambda, g) = \frac{E_p(\lambda, g) \frac{\Delta^2}{\pi R^2}}{\frac{J(\lambda)}{\pi}} = \frac{E_p(\lambda, g)}{\Omega_{\text{object}}} \frac{\pi}{J(\lambda)} \quad (4)$$

<figure><img src="image_6.png" /><figcaption>**Figure 4.** Average observed spectrum deduced from the full set of Probing the Hermean Exosphere by Ultraviolet Spectroscopy observations compared to the composite WHI solar spectrum arbitrarily rescaled by a constant.</figcaption></figure>
<table><caption>**Table 2**

*Derived Reflectance for Several Wavelength Ranges at a Phase Angle ~70°*</caption><thead><tr><th>Spectral interval</th><th>Reflectance (in 10<sup>-3</sup>)</th><th>Uncertainty (random) in 10<sup>-4</sup></th><th>Uncertainty (systematic) range in 10<sup>-3</sup></th></tr></thead><tbody><tr><td>Continuum 1: (87–95 nm)</td><td>3.8</td><td>2.8</td><td>2.5–4.2</td></tr><tr><td>H Lyman-γ: (97.2 nm)</td><td>4.2</td><td>3.0</td><td>3.5–5.5</td></tr><tr><td>H Lyman-β (102.5 nm)</td><td>3.7</td><td>2.4</td><td>2.5–4.2</td></tr><tr><td>Continuum 2 (105–115 nm)</td><td>2.2</td><td>1.9</td><td>1.7–2.5</td></tr><tr><td>H Lyman-α (121.6 nm)</td><td>3.5</td><td>1.4</td><td>1.9–3.8</td></tr><tr><td>Continuum 3 (125–128 nm)</td><td>4.3</td><td>8.6</td><td>2.9–4.7</td></tr><tr><td>O I (130.4 nm)</td><td>3.1</td><td>1.6</td><td>2.1–3.4</td></tr><tr><td>C II (133.5 nm)</td><td>2.5</td><td>0.9</td><td>1.6–2.8</td></tr><tr><td>Continuum 4 (135–138 nm)</td><td>2.5</td><td>1.3</td><td>1.9–2.8</td></tr><tr><td>Si IV (140 nm)</td><td>2.5</td><td>0.9</td><td>1.6–2.7</td></tr><tr><td>Continuum 5 (142–148 nm)</td><td>3.0</td><td>0.7</td><td>2.1–3.3</td></tr><tr><td>Continuum 6 (148–154 nm)</td><td>3.4</td><td>0.7</td><td>2.4–3.7</td></tr><tr><td>Continuum 7 (154–160 nm)</td><td>3.7</td><td>0.7</td><td>2.8–4.1</td></tr></tbody></table>

where $\Omega_{object} = \pi R^2/\Delta^2$ is the solid angle of the object as seen by the observer. Noting $J_T$ the solar irradiance at 1 AU, and $D$ the body-Sun distance (in AU), we can replace $J(\lambda) = J_T(\lambda)/D^2$ to derive the reflectance from the observation ($E_p$) and the solar spectrum at 1 AU $J_T$:

$$[I/F](\lambda, g) = \frac{E_p(\lambda, g)}{\Omega_{object}} \frac{\pi}{J_T(\lambda)} D^2 \quad (5)$$

Since it is a ratio of two spectral quantities, both $E_p$ and $J_T$ can be expressed either in power units (W cm$^{-2}$ nm$^{-1}$) or photon units (ph s$^{-1}$ cm$^{-2}$ nm$^{-1}$).

$E_p(\lambda,g)$ is related to the count rate on the bin, CR.bin (in counts/bin/s), derived from the full set of observations by the following equation:

$$E_p(\lambda, g) = \frac{CRbin)}{S_{eff}(\lambda)\delta\lambda} \quad (6)$$

where $S_{eff}(\lambda)$ is the effective area of the EUV channel of PHEBUS, that is, the entrance pupil area multiplied by the total efficiency of the instrument (including optics and detectors) and the vignetting inside the instrument (e.g., due to the split of the beam coming from the primary mirror on the two gratings (EUV and FUV)), and $\delta\lambda$ is the bin spectral bandpass (spectral width of one bin).

So, $I/F$ can be deduced from the observable $CR.bin$ by

$$[I/F](\lambda, g) = \frac{1}{S_{eff}(\lambda)\delta\lambda} \frac{CRbin)}{\Omega_{object}} \frac{\pi}{J_T(\lambda)} D^2 \quad (7)$$

To avoid potential damage to the detector, the Mercury observations have been carried out with an EUV detector voltage of 3,400 V instead of the nominal 3,600 V one. A first estimate of the effective area has been derived from observations of the star $\alpha$-Eridani at the same voltage above 115 nm, and $\beta$-Cani Majoris at 3,200 V above 90 nm (Appendix B). The systematic uncertainty is estimated to be 10% based on these two stars. This systematic uncertainty may include other parameters affecting the instrumental sensitivity not well estimated yet but expected to be lower than 10% (e.g., polarization,...). Below 90 nm, the starlight is strongly absorbed by the interstellar medium and the effective area has only been estimated above 90 nm.

The solar flux $J_T(\lambda)$, taken from the Whole Heliophysics Interval 2008 (https://lasp.colorado.edu/lisird/data/whi_ref_spectra), is a composite solar irradiance spectrum from 0.1 to 2,400 nm based on TIMED/SEE, SORCE and rocket experiment (Woods et al., 2009). Three spectra corresponding to three periods: 25 March–29 March, 29 March–4 April, and 10 April to 16 April 2008 are available and associated to different sunspot numbers, F10.7 index (83.8, 77.1, and 68.9), etc. Their spectral resolution varies from 0.1 nm below 105 nm and between 116–310 to 0.4 nm between 105 and 116 nm.

In October 2021, the F10.7 monthly average index, measured by the radio telescopes, located at the Dominion Radio Astrophysical Observatory (https://www.spaceweather.gc.ca/forecast-prevision/solar-solaire/solarflux/sx-en.php) was 90.5 and then the solar activity of the first period is similar to that during the PHEBUS observations, and is used here to calculate the reflectance (Table 2, column 1). However, due to the variations of the EUV solar flux with the solar activity, the solar spectrum during our observations may differ from the WHI reference spectrum A possible systematic uncertainty on the derived reflectance is considered by choosing the three periods of WHI (Woods et al., 2009) and the ATLAS-1 and ATLAS-3 spectra (Thuillier et al., 2004). We neglect the noise (random error) on these spectra because it is much smaller than the noise on the spectra measured by PHEBUS. The current systematic uncertainty on the derived reflectance is mainly instrumental (effective area), so a more accurate solar spectrum is not crucial for the first estimate presented in this manuscript, but when the effective area will be improved using future stellar observations, such details should be considered more carefully, for example, by using the measured solar spectrum from TIMED-SEE, SDO-EVE, or MAVEN-EUVM (Eparvier et al., 2015; Woods et al., 2005, 2012).

The resulting statistical uncertainty on the derived $I/F$ is obtained from standard error propagation, while a range of values is derived from the systematic uncertainty (combining the extrema estimated for the solar spectrum and
<figure><img src="image_7.png" /><figcaption>**Figure 5.** Spectral variation of the reflectance at a phase angle of ~70° derived from BepiColombo/PHEBUS compared to values deduced from Mariner 10 (Wu & Broadfoot, 1977), converted to reflectance at 70° (see Appendix A). The reflectance at 76° measured by MESSENGER/MASCS for wavelengths >220 nm (Holsclaw et al., 2010) is also shown. The vertical black bars represent the estimated standard deviation and the gray area represents the estimated range considering the systematic uncertainty on the solar flux and the effective area. Scaled relative reflectivity curve for SiO₂ between 80–180 nm (green curve) is plotted for comparison.</figcaption></figure>

the effective area). In order to reduce the statistical uncertainty on the reflectance, especially associated to solar emission line (Figure 4), we separately estimated the reflectance at these emissions and in the different parts of the continuum. The spectral interval used to calculate the average reflectance, and the different uncertainties are given in Table 2.

The reflectance derived from the spectral range at center wavelength $λ_0$ is calculated from the following equation:

$$[I/F](\lambda_0, g) = \frac{\sum C(\text{bin})}{\int S_{\text{eff}}(\lambda)J_T(\lambda)\delta\lambda} \left\langle \frac{\pi D^2}{\Omega_{\text{object}}} \right\rangle \quad (8)$$

where the sum $Σ(CR(\text{bin}))$ is done on the bins where the emission line is observed or inside the continuum and the integral over $J_T(\lambda)S_{\text{eff}}(\lambda)\delta\lambda$ is the sum of the solar emission line of the WHI spectrum or the sum over the continuum interval. $\langle \pi D^2/\Omega_{\text{mercury}} \rangle$ is the average value for the six observations (Table 1).

The derived reflectance with their error bars and the systematic uncertainty range are compared to Mariner 10 and MESSENGER observations in Figure 5.

## 4. Discussion

The only measured reflectance of Mercury in the studied spectral range, before BepiColombo observations, are those from Mariner 10 during the three flybys of Mercury (Wu & Broadfoot, 1977). The observations were done at a phase angle varying from 106° incoming to 74° outgoing during flybys 1 and 3 and from 50° to 120° during the second encounter (Wu & Broadfoot, 1977). The measured reflectance at each phase angle was normalized to 0° phase angle (geometric albedo) using the integral phase function $Φ_p(g)$ from Hapke (1966), including the Shadow-Hiding Opposite Effect (SHOE), and a value of 0.6 for the h parameter for all wavelengths (Wu & Broadfoot, 1977). Using a similar model (see appendix A), we estimate the value of $Φ_p(70°) = 0.14$, applied it (Equation 1) to convert the geometric albedos measured by Mariner 10 into reflectance at 70°, assuming the spectral variation of this phase function to be small and therefore negligible. The magnitudes of the reflectance measured by BepiColombo/PHEBUS and Mariner 10 (between 0.1% and 0.6%) are of the same order (Figure 5). MESSENGER measured the reflectance of the surface of Mercury at wavelengths >220 nm for a phase angle $g = 76°$ (see Figures 6 and 9 from Holsclaw et al., 2010), similar to the PHEBUS observations.
The spectral variations, considering the systematic uncertainties, measured by PHEBUS display a possible local minimum between 105 and 115 nm and a local maximum between 125 and 128 nm. These maximum and minimum points are not seen at these wavelengths in Mariner's 10 observations (Figure 5) which indicate a noisy decrease of the albedo from 100 to 165.7 nm, similar to that seen on the Moon (Gladstone et al., 1994; Hendrix, Retherford, et al., 2012; Lucke et al., 1976). SiO₂ reflectance was suggested to explain partly the spectral variations on the Moon between 50 and 120 nm (Flynn et al., 1998; Gladstone et al., 1994). Its reflectance presents a local minimum of reflectivity at 115 nm and a local maximum at 120 nm (Philipp, 1985), which could explain the shape of the derived spectral profile between 110–140 nm (Figure 5).

With Φ<sub>p</sub>(70°) = 0.14, the physical albedo A<sub>p</sub>(λ) is between 1% and 4%, lower than the physical albedo of the Moon ~2%–8% (Gladstone et al., 1994; Wu & Broadfoot, 1977), and consistent with a lower FeO concentration on Mercury than on the Moon (Domingue et al., 2014; Hapke, 1977; Murchie et al., 2018 and references therein). This reduced FeO concentration could be due to a larger space weathering of the surface of Mercury.

The surface of airless bodies such as the Moon, Mercury, asteroids, Jovian, or Saturnian satellites is known to be subject to such space weathering processes (Pieters & Noble, 2016). The variations of the optical properties due to space weathering depend on the composition of the surface (e.g., Hendrix, Domingue, & Noll, 2012) but also on the wavelength. For example, it is well-established that the visible and near-infrared reflectance of surfaces bombarded by energetic plasma or micrometeoroids is darker and redder due to the formation of submicroscopic iron phases (SMFe) (Hapke, 2001). Space weathering and the formation of SMFe have been inferred on Mercury from infrared observations (Hapke, 1977, 2001; Lucey & Riner, 2011; Rava & Hapke, 1987; Vilas, 1988). At Mercury, impact vapor deposits are more important than on the Moon (Cintala, 1992) and the interpretation of the Mariner 10 observations suggested that Mercury had a crust with low abundance in ferrous iron (iron (II) like FeO). Hapke (2001) discuss the possibility that almost all FeO could have been converted into SMFe by space weathering on Mercury but rejected this explanation based on theoretical studies, suggesting a SMFe fraction lower than 1% and therefore inconsistent with this explanation (see also Warell & Valegard, 2006). More recent estimates of the SMFe fraction suggest a fraction of SMFe lower than the Moon (<0.5%) (McClintock et al., 2008). However, Lucey and Riner (2011) using a model with different sizes of SMFe were able to reproduce the near-infrared MASCS data with a fraction of 3.5% much larger than the lunar soils, suggesting that a major fraction of the available iron has been processed into submicroscopic iron by space weathering. A limitation of their model was the impossibility to reproduce the observed oxygen-metal charge transfer band observed by MASCS (McClintock et al., 2008).

However, the decrease of the reflectance measured by MESSENGER/MASCS from 1% at 400 nm to 0.25% at 220 nm, close to the value derived from PHEBUS below 160 nm (Figure 5), is more consistent with slopes measured on crushed lunar rocks (from ~0.2 to 0.05) than lunar soils (from 0.08 to 0.04) in contradiction with a larger space-weathering of the surface of Mercury (Hendrix & Vilas, 2006). On the contrary, the upturn of the reflectance below 200 nm is more consistent with the lunar soils (Hendrix & Vilas, 2006). If we assume an integral phase function Φ<sub>p</sub>(70°) = 0.14, the physical albedo A<sub>p</sub> (called absolute reflectance by Hendrix & Vilas, 2006) deduced from Equation 1, decreases from 7% at 400 nm to 2% near 160 nm, which is darker than the physical albedo of crushed lunar rocks by a factor of ~2 (Hendrix & Vilas, 2006). Therefore, UV albedo of Mercury and its spectral variation can't be explained only by the space-weathering effects on the iron at the surface.

Other opaque materials such as carbonaceous materials delivered by micrometeorites (Syal et al., 2015) or the remnants of an ancient graphite-rich crust (Peplowski et al., 2016), present in the darkest terrains of Mercury (Trang et al., 2017), and their UV refractive index measurements (e.g., Applin et al., 2018) will be useful to further interpret these PHEBUS observations in the future.

**5. Conclusion**

Nine days after the first flyby of Mercury by the ESA-JAXA mission BepiColombo, the EUV spectrograph of PHEBUS observed the disk-integrated solar reflected light from the surface of Mercury between 90 and 160 nm at a distance of 4.5 million kilometers. From these observations, we derived the UV reflectance (between 80 and 160 nm) of Mercury's surface more than 40 years after the only measurement done before by Mariner 10. The magnitude of the reflectance measured at a phase angle of 70° is in good agreement with the Mariner 10 observations and with the MESSENGER/MASCS observations at 220 nm. The results confirm a lower EUV
albedo of Mercury compared with the Moon, probably due to a lower FeO concentration, and a possible signature of amorphous SiO₂ that needs to be confirmed by future observations. A number of favorable geometries to observe Mercury during the rest of the cruise exist, but the spacecraft operations could reduce this number (e.g., the observations were not possible after the second flyby due to spacecraft operations). After the insertion around Mercury, the reflected light from the dayside surface of Mercury will be too bright for the instrument to be observed. Therefore, the cruise observations of Mercury from a large distance are the only opportunities to better characterize the UV spectral variations of the reflectance of the surface of Mercury.

## Appendix A: Integral Phase Function

To compare our derived reflectance near 70° to the published physical albedo derived from Mariner 10, we have used the model of the integral phase function given by Wu and Broadfoot (1977). This model is from Hapke (1966) and, even if such a model has been refined later (Hapke, 2012), this old version has to be used to compare with Mariner 10 published disk-integrated reflectance because they were normalized to 0° and the unprocessed values are not available. In this model, the integral phase function is the product of three terms (Hapke, 1966, Equation 9):

$$ \Phi_p(g) = I(g)\Sigma(g)B(g) \quad (A1) $$

$B(g)$ is the retrodirective function which describes the backscattering due to blocking and shadowing effects within the lunar soil and depends on a parameter $h$ which defines the sharpness of the brightness near $g = 0°$.

$$ B(g) = \begin{cases} 2 - \frac{\tan(g)}{2h}(1 - \exp[-h\tan(g)])(3 - \exp[-h\tan(g)])_{g<\pi/2} \\ 1 \quad g>\pi/2 \end{cases} \quad (A2) $$

$\Sigma(g)$ describes the average angular scattering function of a single particle of the lunar soil and is the sum of the scattering function of a sphere, each of whose elements reflect the light according to the Lambert's law (Schoenberg function) and an empirical forward scattering term describing the light transmitted through the particle.

$$ \Sigma(g) = \frac{\sin(g) + (\pi - g)\cos(g)}{\pi} + 0.1[1 - \cos(g)]^2 \quad (A3) $$

and $I(g)$ is the integral of the reflection function of a surface whose reflectance obeys to the Lommel-Seeliger law, over the part of the Hermean sphere that is both visible and illuminated. $I(g)$ is given by Equation A4 (Hapke, 1963, 1966)

$$ I(g) = \frac{1}{2} \left( 1 + \sin\left(\frac{g}{2}\right) \tan\left(\frac{g}{2}\right) \ln\left[\tan\left(\frac{g}{4}\right)\right] \right) \quad (A4) $$

<figure><img src="image_8.png" /><figcaption>Figure A1. Integral phase function derived from the Hapke (1966) model with a parameter $h = 0.6$.</figcaption></figure>
The function $\Phi_{\rho}(g)$ for $h = 0.6$ (Wu & Broadfoot, 1977) is shown in Figure A1.

## Appendix B: EUV Effective Area

The EUV effective area was derived from $\alpha$-Eridani observation at 3,400 V above 115 nm and from $\beta$ Cani-Majoris at 3,200 V above 90 nm (Figure B1) and their measured count rate is given in Tables B1 and B2. These two observations were performed during the cruise. A shift in the wavelength given in these tables is applied to match the absorption lines in the reference spectra. The reference spectra are those of the catalog Fully ON-line Datacenter for Ultraviolet Emissions (FONDUE) (Snow et al., 2013). The effective area derived from $\beta$ Cani-Majoris is rescaled to consider the difference in high voltage, and smoothed to remove the spectral feature to derive the effective area of PHEBUS (Figure B1). From the differences between the effective area derived with the two stars, we consider a possible systematic uncertainty of 10%.

<figure><img src="image_9.png" /><figcaption>**Figure B1.** Effective area of Probing the Hermean Exosphere by Ultraviolet Spectroscopy (solid black line). The effective area between 115 and 160 nm derived from $\alpha$-Eridani at HV = 3,400 V is shown in green, and the effective area between 90 and 160 nm derived from $\beta$ Cani-Majoris at HV = 3,200 V and rescaled to take into account the difference in HV is shown in blue. The solid black dashed lines bracket the considered systematic uncertainty.</figcaption></figure>

<caption>**Table B1**</caption>

Count Rate Measured for $\alpha$-Eridani and Its Uncertainty for a Total Integration Time of 480 s

<table><thead><tr><td>Pixel wavelength (nm)</td><td>Count rate (counts/s)</td><td>Uncertainty (counts/s)</td></tr></thead><tbody><tr><td>80.0810</td><td>0.152448</td><td>0.0233854</td></tr><tr><td>80.3440</td><td>0.179993</td><td>0.0235702</td></tr><tr><td>80.6070</td><td>0.221660</td><td>0.0253448</td></tr><tr><td>80.8700</td><td>0.160081</td><td>0.0230112</td></tr><tr><td>81.1330</td><td>0.167251</td><td>0.0236621</td></tr><tr><td>81.3960</td><td>0.165060</td><td>0.0225347</td></tr><tr><td>81.6590</td><td>0.173919</td><td>0.0234780</td></tr><tr><td>81.9220</td><td>0.171463</td><td>0.0232924</td></tr><tr><td>82.1850</td><td>0.183415</td><td>0.0235702</td></tr><tr><td>82.4480</td><td>0.209380</td><td>0.0244736</td></tr><tr><td>82.7110</td><td>0.174709</td><td>0.0231053</td></tr><tr><td>82.9740</td><td>0.149906</td><td>0.0218502</td></tr><tr><td>83.2370</td><td>0.218481</td><td>0.0247382</td></tr><tr><td>83.5000</td><td>0.225346</td><td>0.0244736</td></tr><tr><td>83.7630</td><td>0.188592</td><td>0.0230112</td></tr><tr><td>84.0260</td><td>0.185565</td><td>0.0228218</td></tr></tbody></table>
<table><caption>Table B1</caption><thead><tr><th>Pixel wavelength (nm)</th><th>Count rate (counts/s)</th><th>Uncertainty (counts/s)</th></tr></thead><tbody><tr><td>84.2890</td><td>0.168481</td><td>0.0225347</td></tr><tr><td>84.5520</td><td>0.225719</td><td>0.0245621</td></tr><tr><td>84.8150</td><td>0.190675</td><td>0.0231053</td></tr><tr><td>85.0780</td><td>0.192561</td><td>0.0232924</td></tr><tr><td>85.3410</td><td>0.161706</td><td>0.0216506</td></tr><tr><td>85.6040</td><td>0.158702</td><td>0.0211435</td></tr><tr><td>85.8670</td><td>0.217605</td><td>0.0238448</td></tr><tr><td>86.1300</td><td>0.206619</td><td>0.0233854</td></tr><tr><td>86.3930</td><td>0.213089</td><td>0.0232924</td></tr><tr><td>86.6560</td><td>0.217058</td><td>0.0235702</td></tr><tr><td>86.9190</td><td>0.211926</td><td>0.0235702</td></tr><tr><td>87.1820</td><td>0.192803</td><td>0.0226308</td></tr><tr><td>87.4450</td><td>0.207189</td><td>0.0233854</td></tr><tr><td>87.7080</td><td>0.214799</td><td>0.0232924</td></tr><tr><td>87.9710</td><td>0.206026</td><td>0.0236621</td></tr><tr><td>88.2340</td><td>0.173855</td><td>0.0218502</td></tr><tr><td>88.4970</td><td>0.221072</td><td>0.0232924</td></tr><tr><td>88.7600</td><td>0.196970</td><td>0.0228218</td></tr><tr><td>89.0230</td><td>0.222190</td><td>0.0235702</td></tr><tr><td>89.2860</td><td>0.213636</td><td>0.0235702</td></tr><tr><td>89.5490</td><td>0.225171</td><td>0.0242956</td></tr><tr><td>89.8120</td><td>0.268176</td><td>0.0259373</td></tr><tr><td>90.0750</td><td>0.237298</td><td>0.0247382</td></tr><tr><td>90.3380</td><td>0.263636</td><td>0.0256851</td></tr><tr><td>90.6010</td><td>0.203022</td><td>0.0231990</td></tr><tr><td>90.8640</td><td>0.256816</td><td>0.0254303</td></tr><tr><td>91.1270</td><td>0.177057</td><td>0.0222439</td></tr><tr><td>91.3900</td><td>0.253417</td><td>0.0251730</td></tr><tr><td>91.6530</td><td>0.291663</td><td>0.0268419</td></tr><tr><td>91.9160</td><td>0.217255</td><td>0.0234780</td></tr><tr><td>92.1790</td><td>0.241618</td><td>0.0253448</td></tr><tr><td>92.4420</td><td>0.285193</td><td>0.0269226</td></tr><tr><td>92.7050</td><td>0.282714</td><td>0.0270031</td></tr><tr><td>92.9680</td><td>0.366815</td><td>0.0299739</td></tr><tr><td>93.2310</td><td>0.441290</td><td>0.0320725</td></tr><tr><td>93.4940</td><td>0.473263</td><td>0.0333984</td></tr><tr><td>93.7570</td><td>0.574008</td><td>0.0365029</td></tr><tr><td>94.0200</td><td>0.666268</td><td>0.0388641</td></tr><tr><td>94.2830</td><td>0.898240</td><td>0.0448764</td></tr><tr><td>94.5460</td><td>1.37778</td><td>0.0549226</td></tr><tr><td>94.8090</td><td>1.65826</td><td>0.0600564</td></tr><tr><td>95.0720</td><td>2.09730</td><td>0.0671532</td></tr><tr><td>95.3350</td><td>3.99197</td><td>0.0920447</td></tr></tbody></table>

*Continued*
<table><caption>Table B1</caption><thead><tr><th>Pixel wavelength (nm)</th><th>Count rate (counts/s)</th><th>Uncertainty (counts/s)</th></tr></thead><tbody><tr><td>95.5980</td><td>5.59067</td><td>0.108553</td></tr><tr><td>95.8610</td><td>4.88820</td><td>0.101636</td></tr><tr><td>96.1240</td><td>3.36793</td><td>0.0846254</td></tr><tr><td>96.3870</td><td>3.75980</td><td>0.0892922</td></tr><tr><td>96.6500</td><td>8.03649</td><td>0.129971</td></tr><tr><td>96.9130</td><td>14.1827</td><td>0.172338</td></tr><tr><td>97.1760</td><td>16.5776</td><td>0.186211</td></tr><tr><td>97.4390</td><td>16.4922</td><td>0.185732</td></tr><tr><td>97.7020</td><td>15.6263</td><td>0.180794</td></tr><tr><td>97.9650</td><td>12.9501</td><td>0.164702</td></tr><tr><td>98.2280</td><td>7.72624</td><td>0.127493</td></tr><tr><td>98.4910</td><td>3.33738</td><td>0.0844457</td></tr><tr><td>98.7540</td><td>2.15124</td><td>0.0681158</td></tr><tr><td>99.0170</td><td>3.81616</td><td>0.0902110</td></tr><tr><td>99.2800</td><td>8.14019</td><td>0.130985</td></tr><tr><td>99.5430</td><td>12.4610</td><td>0.161777</td></tr><tr><td>99.8060</td><td>13.1180</td><td>0.165936</td></tr><tr><td>100.069</td><td>10.7409</td><td>0.150275</td></tr><tr><td>100.332</td><td>9.96784</td><td>0.144788</td></tr><tr><td>100.595</td><td>10.8510</td><td>0.151024</td></tr><tr><td>100.858</td><td>13.7340</td><td>0.169699</td></tr><tr><td>101.121</td><td>18.8790</td><td>0.198836</td></tr><tr><td>101.384</td><td>23.5847</td><td>0.222127</td></tr><tr><td>101.647</td><td>25.3549</td><td>0.230310</td></tr><tr><td>101.910</td><td>24.9089</td><td>0.228294</td></tr><tr><td>102.173</td><td>23.4547</td><td>0.221589</td></tr><tr><td>102.436</td><td>22.2596</td><td>0.215944</td></tr><tr><td>102.699</td><td>25.2852</td><td>0.229989</td></tr><tr><td>102.962</td><td>23.7407</td><td>0.222897</td></tr><tr><td>103.225</td><td>20.6202</td><td>0.207843</td></tr><tr><td>103.488</td><td>13.7151</td><td>0.169737</td></tr><tr><td>103.751</td><td>6.19126</td><td>0.114602</td></tr><tr><td>104.014</td><td>3.32477</td><td>0.0846767</td></tr><tr><td>104.277</td><td>6.65185</td><td>0.118750</td></tr><tr><td>104.540</td><td>12.2008</td><td>0.160037</td></tr><tr><td>104.803</td><td>13.6699</td><td>0.169456</td></tr><tr><td>105.066</td><td>11.3604</td><td>0.154659</td></tr><tr><td>105.329</td><td>20.1301</td><td>0.205280</td></tr><tr><td>105.592</td><td>32.3534</td><td>0.260016</td></tr><tr><td>105.855</td><td>38.4848</td><td>0.283448</td></tr><tr><td>106.118</td><td>39.2667</td><td>0.286366</td></tr><tr><td>106.381</td><td>37.3673</td><td>0.279322</td></tr><tr><td>106.644</td><td>36.4620</td><td>0.275906</td></tr></tbody></table>

Continued
<table><caption>Table B1</caption><thead><tr><th>Pixel wavelength (nm)</th><th>Count rate (counts/s)</th><th>Uncertainty (counts/s)</th></tr></thead><tbody><tr><td>106.907</td><td>34.4385</td><td>0.268160</td></tr><tr><td>107.170</td><td>34.1594</td><td>0.267098</td></tr><tr><td>107.433</td><td>35.4208</td><td>0.271929</td></tr><tr><td>107.696</td><td>32.7935</td><td>0.261631</td></tr><tr><td>107.959</td><td>30.9335</td><td>0.254124</td></tr><tr><td>108.222</td><td>31.6844</td><td>0.257264</td></tr><tr><td>108.485</td><td>34.5128</td><td>0.268435</td></tr><tr><td>108.748</td><td>34.0160</td><td>0.266545</td></tr><tr><td>109.011</td><td>34.7441</td><td>0.269331</td></tr><tr><td>109.274</td><td>36.9672</td><td>0.277764</td></tr><tr><td>109.537</td><td>35.9120</td><td>0.273845</td></tr><tr><td>109.800</td><td>28.8739</td><td>0.245621</td></tr><tr><td>110.063</td><td>26.6497</td><td>0.236015</td></tr><tr><td>110.326</td><td>31.6192</td><td>0.257003</td></tr><tr><td>110.589</td><td>33.1531</td><td>0.263119</td></tr><tr><td>110.852</td><td>34.8989</td><td>0.269991</td></tr><tr><td>111.115</td><td>34.7955</td><td>0.269556</td></tr><tr><td>111.378</td><td>34.5404</td><td>0.268564</td></tr><tr><td>111.641</td><td>35.8010</td><td>0.273401</td></tr><tr><td>111.904</td><td>36.2319</td><td>0.275032</td></tr><tr><td>112.167</td><td>31.9799</td><td>0.258518</td></tr><tr><td>112.430</td><td>27.0413</td><td>0.237765</td></tr><tr><td>112.693</td><td>27.6258</td><td>0.240307</td></tr><tr><td>112.956</td><td>31.3924</td><td>0.256165</td></tr><tr><td>113.219</td><td>34.4669</td><td>0.268354</td></tr><tr><td>113.482</td><td>33.1289</td><td>0.263177</td></tr><tr><td>113.745</td><td>31.2598</td><td>0.255640</td></tr><tr><td>114.008</td><td>29.1593</td><td>0.246934</td></tr><tr><td>114.271</td><td>27.3534</td><td>0.239148</td></tr><tr><td>114.534</td><td>29.6710</td><td>0.249069</td></tr><tr><td>114.797</td><td>33.0799</td><td>0.262963</td></tr><tr><td>115.060</td><td>33.8566</td><td>0.266039</td></tr><tr><td>115.323</td><td>32.4019</td><td>0.260400</td></tr><tr><td>115.586</td><td>31.0308</td><td>0.254942</td></tr><tr><td>115.849</td><td>31.3153</td><td>0.256292</td></tr><tr><td>116.112</td><td>32.1778</td><td>0.260016</td></tr><tr><td>116.375</td><td>34.8694</td><td>0.271234</td></tr><tr><td>116.638</td><td>35.4915</td><td>0.274542</td></tr><tr><td>116.901</td><td>34.4285</td><td>0.272001</td></tr><tr><td>117.164</td><td>34.8160</td><td>0.277099</td></tr><tr><td>117.427</td><td>35.5135</td><td>0.285622</td></tr><tr><td>117.690</td><td>35.5812</td><td>0.292647</td></tr><tr><td>117.953</td><td>35.7446</td><td>0.298739</td></tr></tbody></table>

Continued
<table><caption>Table B1</caption><thead><tr><th>Pixel wavelength (nm)</th><th>Count rate (counts/s)</th><th>Uncertainty (counts/s)</th></tr></thead><tbody><tr><td>118.216</td><td>34.5260</td><td>0.299261</td></tr><tr><td>118.479</td><td>33.6930</td><td>0.298506</td></tr><tr><td>118.742</td><td>32.0562</td><td>0.294966</td></tr><tr><td>119.005</td><td>29.4979</td><td>0.287885</td></tr><tr><td>119.268</td><td>28.9305</td><td>0.286971</td></tr><tr><td>119.531</td><td>32.4666</td><td>0.301465</td></tr><tr><td>119.794</td><td>33.3643</td><td>0.305299</td></tr><tr><td>120.057</td><td>33.5241</td><td>0.307685</td></tr><tr><td>120.320</td><td>31.1026</td><td>0.300571</td></tr><tr><td>120.583</td><td>29.0213</td><td>0.294488</td></tr><tr><td>120.846</td><td>27.6111</td><td>0.290743</td></tr><tr><td>121.109</td><td>25.6612</td><td>0.285097</td></tr><tr><td>121.372</td><td>24.5348</td><td>0.282013</td></tr><tr><td>121.635</td><td>20.6061</td><td>0.268022</td></tr><tr><td>121.898</td><td>16.2416</td><td>0.251730</td></tr><tr><td>122.161</td><td>11.8253</td><td>0.233287</td></tr><tr><td>122.424</td><td>9.96845</td><td>0.225568</td></tr><tr><td>122.687</td><td>9.03385</td><td>0.222127</td></tr><tr><td>122.950</td><td>9.42838</td><td>0.223199</td></tr><tr><td>123.213</td><td>9.79414</td><td>0.223859</td></tr><tr><td>123.476</td><td>12.4620</td><td>0.233296</td></tr><tr><td>123.739</td><td>16.8635</td><td>0.249113</td></tr><tr><td>124.002</td><td>19.2072</td><td>0.253200</td></tr><tr><td>124.265</td><td>22.4596</td><td>0.259147</td></tr><tr><td>124.528</td><td>25.0561</td><td>0.259908</td></tr><tr><td>124.791</td><td>26.1558</td><td>0.254389</td></tr><tr><td>125.054</td><td>28.8422</td><td>0.257467</td></tr><tr><td>125.317</td><td>30.2708</td><td>0.259423</td></tr><tr><td>125.580</td><td>31.3061</td><td>0.261954</td></tr><tr><td>125.843</td><td>32.4917</td><td>0.265443</td></tr><tr><td>126.106</td><td>32.8073</td><td>0.265525</td></tr><tr><td>126.369</td><td>32.5302</td><td>0.263581</td></tr><tr><td>126.632</td><td>32.3546</td><td>0.262318</td></tr><tr><td>126.895</td><td>32.0836</td><td>0.260841</td></tr><tr><td>127.158</td><td>32.5538</td><td>0.262144</td></tr><tr><td>127.421</td><td>32.0983</td><td>0.260075</td></tr><tr><td>127.684</td><td>31.8000</td><td>0.258703</td></tr><tr><td>127.947</td><td>30.5245</td><td>0.253217</td></tr><tr><td>128.210</td><td>30.3786</td><td>0.252470</td></tr><tr><td>128.473</td><td>30.9300</td><td>0.254644</td></tr><tr><td>128.736</td><td>32.1466</td><td>0.259457</td></tr><tr><td>128.999</td><td>32.1544</td><td>0.259415</td></tr><tr><td>129.262</td><td>31.9177</td><td>0.258401</td></tr></tbody></table>

*Continued*
<table><caption>Table B1</caption><thead><tr><th>Pixel wavelength (nm)</th><th>Count rate (counts/s)</th><th>Uncertainty (counts/s)</th></tr></thead><tbody><tr><td>129.525</td><td>31.1763</td><td>0.255359</td></tr><tr><td>129.788</td><td>31.1704</td><td>0.255291</td></tr><tr><td>130.051</td><td>31.7672</td><td>0.257694</td></tr><tr><td>130.314</td><td>31.0697</td><td>0.254866</td></tr><tr><td>130.577</td><td>30.2173</td><td>0.251299</td></tr><tr><td>130.840</td><td>28.6226</td><td>0.244568</td></tr><tr><td>131.103</td><td>27.3342</td><td>0.238985</td></tr><tr><td>131.366</td><td>25.6586</td><td>0.231541</td></tr><tr><td>131.629</td><td>25.1823</td><td>0.229403</td></tr><tr><td>131.892</td><td>24.5734</td><td>0.226595</td></tr><tr><td>132.155</td><td>24.4723</td><td>0.226135</td></tr><tr><td>132.418</td><td>25.6770</td><td>0.231644</td></tr><tr><td>132.681</td><td>25.5310</td><td>0.230940</td></tr><tr><td>132.944</td><td>26.0308</td><td>0.233250</td></tr><tr><td>133.207</td><td>27.6590</td><td>0.240406</td></tr><tr><td>133.470</td><td>28.0537</td><td>0.242035</td></tr><tr><td>133.733</td><td>27.9653</td><td>0.241676</td></tr><tr><td>133.996</td><td>27.5219</td><td>0.239764</td></tr><tr><td>134.259</td><td>27.5751</td><td>0.239991</td></tr><tr><td>134.522</td><td>26.7331</td><td>0.236300</td></tr><tr><td>134.785</td><td>26.4551</td><td>0.235066</td></tr><tr><td>135.048</td><td>25.2781</td><td>0.229866</td></tr><tr><td>135.311</td><td>24.5658</td><td>0.226576</td></tr><tr><td>135.574</td><td>24.5817</td><td>0.226662</td></tr><tr><td>135.837</td><td>25.1891</td><td>0.229432</td></tr><tr><td>136.100</td><td>25.7496</td><td>0.231934</td></tr><tr><td>136.363</td><td>26.3681</td><td>0.234706</td></tr><tr><td>136.626</td><td>25.8928</td><td>0.232551</td></tr><tr><td>136.889</td><td>26.0907</td><td>0.233436</td></tr><tr><td>137.152</td><td>25.6778</td><td>0.231578</td></tr><tr><td>137.415</td><td>25.8058</td><td>0.232215</td></tr><tr><td>137.678</td><td>25.5467</td><td>0.231034</td></tr><tr><td>137.941</td><td>25.6606</td><td>0.231503</td></tr><tr><td>138.204</td><td>24.8821</td><td>0.228018</td></tr><tr><td>138.467</td><td>24.6528</td><td>0.226978</td></tr><tr><td>138.730</td><td>24.7034</td><td>0.227150</td></tr><tr><td>138.993</td><td>24.6115</td><td>0.226710</td></tr><tr><td>139.256</td><td>23.9818</td><td>0.223830</td></tr><tr><td>139.519</td><td>23.8782</td><td>0.223345</td></tr><tr><td>139.782</td><td>23.1926</td><td>0.220135</td></tr><tr><td>140.045</td><td>23.2060</td><td>0.220233</td></tr><tr><td>140.308</td><td>22.8322</td><td>0.218393</td></tr><tr><td>140.571</td><td>22.8479</td><td>0.218462</td></tr></tbody></table>

*Continued*
<table><caption>Table B1</caption><thead><tr><th>Pixel wavelength (nm)</th><th>Count rate (counts/s)</th><th>Uncertainty (counts/s)</th></tr></thead><tbody><tr><td>140.834</td><td>22.6369</td><td>0.217516</td></tr><tr><td>141.097</td><td>21.6471</td><td>0.212765</td></tr><tr><td>141.360</td><td>21.3085</td><td>0.211014</td></tr><tr><td>141.623</td><td>21.6846</td><td>0.212918</td></tr><tr><td>141.886</td><td>21.6882</td><td>0.212908</td></tr><tr><td>142.149</td><td>21.7357</td><td>0.213132</td></tr><tr><td>142.412</td><td>21.7981</td><td>0.213417</td></tr><tr><td>142.675</td><td>21.9107</td><td>0.213986</td></tr><tr><td>142.938</td><td>21.8795</td><td>0.213773</td></tr><tr><td>143.201</td><td>21.9163</td><td>0.213966</td></tr><tr><td>143.464</td><td>21.9973</td><td>0.214401</td></tr><tr><td>143.727</td><td>21.4803</td><td>0.211835</td></tr><tr><td>143.990</td><td>21.4920</td><td>0.211938</td></tr><tr><td>144.253</td><td>21.2590</td><td>0.210798</td></tr><tr><td>144.516</td><td>21.3648</td><td>0.211261</td></tr><tr><td>144.779</td><td>21.6113</td><td>0.212490</td></tr><tr><td>145.042</td><td>21.2559</td><td>0.210695</td></tr><tr><td>145.305</td><td>21.1505</td><td>0.210210</td></tr><tr><td>145.568</td><td>21.3034</td><td>0.210983</td></tr><tr><td>145.831</td><td>20.8515</td><td>0.208729</td></tr><tr><td>146.094</td><td>21.2935</td><td>0.210963</td></tr><tr><td>146.357</td><td>20.9958</td><td>0.209476</td></tr><tr><td>146.620</td><td>21.1528</td><td>0.210241</td></tr><tr><td>146.883</td><td>21.0248</td><td>0.209569</td></tr><tr><td>147.146</td><td>21.0549</td><td>0.209756</td></tr><tr><td>147.409</td><td>20.8331</td><td>0.208614</td></tr><tr><td>147.672</td><td>20.7072</td><td>0.208010</td></tr><tr><td>147.935</td><td>20.5191</td><td>0.207038</td></tr><tr><td>148.198</td><td>20.6672</td><td>0.207833</td></tr><tr><td>148.461</td><td>20.1485</td><td>0.205185</td></tr><tr><td>148.724</td><td>19.9966</td><td>0.204369</td></tr><tr><td>148.987</td><td>19.7430</td><td>0.203101</td></tr><tr><td>149.250</td><td>19.9564</td><td>0.204230</td></tr><tr><td>149.513</td><td>19.6055</td><td>0.202362</td></tr><tr><td>149.776</td><td>19.3464</td><td>0.201071</td></tr><tr><td>150.039</td><td>18.9604</td><td>0.199097</td></tr><tr><td>150.302</td><td>18.5771</td><td>0.197015</td></tr><tr><td>150.565</td><td>18.1918</td><td>0.194989</td></tr><tr><td>150.828</td><td>17.6926</td><td>0.192322</td></tr><tr><td>151.091</td><td>18.1295</td><td>0.194644</td></tr><tr><td>151.354</td><td>18.0311</td><td>0.194086</td></tr><tr><td>151.617</td><td>17.6341</td><td>0.192017</td></tr><tr><td>151.880</td><td>17.4712</td><td>0.191088</td></tr></tbody></table>
<table><caption>Table B1</caption><thead><tr><th>Pixel wavelength (nm)</th><th>Count rate (counts/s)</th><th>Uncertainty (counts/s)</th></tr></thead><tbody><tr><td>152.143</td><td>17.2892</td><td>0.190109</td></tr><tr><td>152.406</td><td>16.5500</td><td>0.185989</td></tr><tr><td>152.669</td><td>16.8333</td><td>0.187604</td></tr><tr><td>152.932</td><td>16.2812</td><td>0.184478</td></tr><tr><td>153.195</td><td>16.1248</td><td>0.183570</td></tr><tr><td>153.458</td><td>16.0229</td><td>0.182978</td></tr><tr><td>153.721</td><td>15.3848</td><td>0.179348</td></tr><tr><td>153.984</td><td>15.2546</td><td>0.178560</td></tr><tr><td>154.247</td><td>15.1566</td><td>0.177988</td></tr><tr><td>154.510</td><td>14.7422</td><td>0.175570</td></tr><tr><td>154.773</td><td>14.6315</td><td>0.174864</td></tr><tr><td>155.036</td><td>14.0745</td><td>0.171493</td></tr><tr><td>155.299</td><td>13.6261</td><td>0.168814</td></tr><tr><td>155.562</td><td>13.1714</td><td>0.165949</td></tr><tr><td>155.825</td><td>12.8803</td><td>0.164068</td></tr><tr><td>156.088</td><td>12.4809</td><td>0.161509</td></tr><tr><td>156.351</td><td>12.4347</td><td>0.161280</td></tr><tr><td>156.614</td><td>12.3184</td><td>0.160498</td></tr><tr><td>156.877</td><td>12.0544</td><td>0.158689</td></tr><tr><td>157.140</td><td>11.6396</td><td>0.156042</td></tr><tr><td>157.403</td><td>11.1379</td><td>0.152582</td></tr><tr><td>157.666</td><td>10.8069</td><td>0.150289</td></tr><tr><td>157.929</td><td>10.8925</td><td>0.150952</td></tr><tr><td>158.192</td><td>10.3398</td><td>0.147004</td></tr><tr><td>158.455</td><td>10.0728</td><td>0.145177</td></tr><tr><td>158.718</td><td>9.92204</td><td>0.144021</td></tr><tr><td>158.981</td><td>9.47355</td><td>0.140745</td></tr><tr><td>159.244</td><td>8.88019</td><td>0.136247</td></tr><tr><td>159.507</td><td>8.47243</td><td>0.133089</td></tr><tr><td>159.770</td><td>8.09574</td><td>0.130071</td></tr><tr><td>160.033</td><td>7.74252</td><td>0.127220</td></tr><tr><td>160.296</td><td>7.00846</td><td>0.120977</td></tr><tr><td>160.559</td><td>6.71943</td><td>0.118512</td></tr><tr><td>160.822</td><td>6.34254</td><td>0.115131</td></tr><tr><td>161.085</td><td>5.54447</td><td>0.107569</td></tr><tr><td>161.348</td><td>4.18691</td><td>0.0934718</td></tr><tr><td>161.611</td><td>3.74561</td><td>0.0884374</td></tr><tr><td>161.874</td><td>3.09239</td><td>0.0803908</td></tr><tr><td>162.137</td><td>2.56210</td><td>0.0731247</td></tr><tr><td>162.400</td><td>2.21873</td><td>0.0680839</td></tr><tr><td>162.663</td><td>2.02706</td><td>0.0650854</td></tr><tr><td>162.926</td><td>1.82289</td><td>0.0617314</td></tr><tr><td>163.189</td><td>1.75548</td><td>0.0605243</td></tr></tbody></table>

Continued
<table><caption>**Table B1**</caption><caption>Continued</caption><thead><tr><th>Pixel wavelength (nm)</th><th>Count rate (counts/s)</th><th>Uncertainty (counts/s)</th></tr></thead><tbody><tr><td>163.452</td><td>1.51741</td><td>0.0562886</td></tr><tr><td>163.715</td><td>1.31855</td><td>0.0524570</td></tr><tr><td>163.978</td><td>1.21230</td><td>0.0503029</td></tr><tr><td>164.241</td><td>1.12346</td><td>0.0485019</td></tr><tr><td>164.504</td><td>0.981052</td><td>0.0452616</td></tr><tr><td>164.767</td><td>0.880285</td><td>0.0429490</td></tr><tr><td>165.030</td><td>0.853026</td><td>0.0421843</td></tr><tr><td>165.293</td><td>0.735219</td><td>0.0391977</td></tr><tr><td>165.556</td><td>0.705110</td><td>0.0383582</td></tr><tr><td>165.819</td><td>0.612873</td><td>0.0357824</td></tr><tr><td>166.082</td><td>0.593552</td><td>0.0352324</td></tr><tr><td>166.345</td><td>0.576886</td><td>0.0347361</td></tr><tr><td>166.608</td><td>0.520263</td><td>0.0329404</td></tr><tr><td>166.871</td><td>0.413245</td><td>0.0294628</td></tr><tr><td>167.134</td><td>0.423289</td><td>0.0297560</td></tr><tr><td>167.397</td><td>0.338443</td><td>0.0265982</td></tr><tr><td>167.660</td><td>0.325943</td><td>0.0261041</td></tr><tr><td>167.923</td><td>0.348860</td><td>0.0270031</td></tr><tr><td>168.186</td><td>0.262500</td><td>0.0233854</td></tr><tr><td>168.449</td><td>0.318750</td><td>0.0257694</td></tr><tr><td>168.712</td><td>0.289583</td><td>0.0245621</td></tr><tr><td>168.975</td><td>0.288443</td><td>0.0245621</td></tr><tr><td>169.238</td><td>0.322346</td><td>0.0259373</td></tr><tr><td>169.501</td><td>0.255110</td><td>0.0231053</td></tr><tr><td>169.764</td><td>0.303026</td><td>0.0251730</td></tr><tr><td>170.027</td><td>0.322346</td><td>0.0259373</td></tr><tr><td>170.290</td><td>0.322346</td><td>0.0259373</td></tr></tbody></table>

<table><caption>**Table B2**</caption><caption>Count Rate Measured for β Cani-Majoris and Its Uncertainty for a Total Integration Time of 480 s</caption><thead><tr><th>Pixel wavelength (nm)</th><th>Count rate (counts/s)</th><th>Uncertainty (counts/s)</th></tr></thead><tbody><tr><td>80.0810</td><td>0.207450</td><td>0.0218502</td></tr><tr><td>80.3440</td><td>0.309469</td><td>0.0261041</td></tr><tr><td>80.6070</td><td>0.319885</td><td>0.0265165</td></tr><tr><td>80.8700</td><td>0.286617</td><td>0.0253448</td></tr><tr><td>81.1330</td><td>0.326353</td><td>0.0270031</td></tr><tr><td>81.3960</td><td>0.310104</td><td>0.0261871</td></tr><tr><td>81.6590</td><td>0.340236</td><td>0.0273227</td></tr><tr><td>81.9220</td><td>0.322845</td><td>0.0266797</td></tr><tr><td>82.1850</td><td>0.340719</td><td>0.0273227</td></tr><tr><td>82.4480</td><td>0.326377</td><td>0.0267609</td></tr><tr><td>82.7110</td><td>0.334622</td><td>0.0271633</td></tr></tbody></table>
<caption>Table B2</caption>

*Continued*

<table><thead><tr><td>Pixel wavelength (nm)</td><td>Count rate (counts/s)</td><td>Uncertainty (counts/s)</td></tr></thead><tbody><tr><td>82.9740</td><td>0.397057</td><td>0.0293151</td></tr><tr><td>83.2370</td><td>0.341925</td><td>0.0273227</td></tr><tr><td>83.5000</td><td>0.446115</td><td>0.0308305</td></tr><tr><td>83.7630</td><td>0.427277</td><td>0.0302622</td></tr><tr><td>84.0260</td><td>0.409798</td><td>0.0297560</td></tr><tr><td>84.2890</td><td>0.434469</td><td>0.0306894</td></tr><tr><td>84.5520</td><td>0.452913</td><td>0.0311805</td></tr><tr><td>84.8150</td><td>0.552913</td><td>0.0343592</td></tr><tr><td>85.0780</td><td>0.492496</td><td>0.0324760</td></tr><tr><td>85.3410</td><td>0.573746</td><td>0.0349851</td></tr><tr><td>85.6040</td><td>0.527913</td><td>0.0335927</td></tr><tr><td>85.8670</td><td>0.590413</td><td>0.0354779</td></tr><tr><td>86.1300</td><td>0.579119</td><td>0.0351090</td></tr><tr><td>86.3930</td><td>0.539865</td><td>0.0338502</td></tr><tr><td>86.6560</td><td>0.608133</td><td>0.0359035</td></tr><tr><td>86.9190</td><td>0.719668</td><td>0.0390312</td></tr><tr><td>87.1820</td><td>0.743461</td><td>0.0396928</td></tr><tr><td>87.4450</td><td>0.688812</td><td>0.0382449</td></tr><tr><td>87.7080</td><td>0.860369</td><td>0.0426448</td></tr><tr><td>87.9710</td><td>0.868614</td><td>0.0428985</td></tr><tr><td>88.2340</td><td>0.872210</td><td>0.0430500</td></tr><tr><td>88.4970</td><td>0.845721</td><td>0.0421843</td></tr><tr><td>88.7600</td><td>1.02936</td><td>0.0465848</td></tr><tr><td>89.0230</td><td>0.984822</td><td>0.0455007</td></tr><tr><td>89.2860</td><td>1.04313</td><td>0.0469560</td></tr><tr><td>89.5490</td><td>1.14802</td><td>0.0492125</td></tr><tr><td>89.8120</td><td>1.25204</td><td>0.0513279</td></tr><tr><td>90.0750</td><td>1.33857</td><td>0.0530739</td></tr><tr><td>90.3380</td><td>1.46429</td><td>0.0554730</td></tr><tr><td>90.6010</td><td>1.66125</td><td>0.0590727</td></tr><tr><td>90.8640</td><td>1.94201</td><td>0.0638398</td></tr><tr><td>91.1270</td><td>2.46173</td><td>0.0718070</td></tr><tr><td>91.3900</td><td>3.00508</td><td>0.0792762</td></tr><tr><td>91.6530</td><td>3.70949</td><td>0.0880439</td></tr><tr><td>91.9160</td><td>4.64316</td><td>0.0984471</td></tr><tr><td>92.1790</td><td>5.75059</td><td>0.109588</td></tr><tr><td>92.4420</td><td>6.69114</td><td>0.118182</td></tr><tr><td>92.7050</td><td>8.51548</td><td>0.133333</td></tr><tr><td>92.9680</td><td>9.88633</td><td>0.143599</td></tr><tr><td>93.2310</td><td>10.8785</td><td>0.150621</td></tr><tr><td>93.4940</td><td>11.8022</td><td>0.156901</td></tr><tr><td>93.7570</td><td>13.5202</td><td>0.167925</td></tr><tr><td>94.0200</td><td>14.3951</td><td>0.173255</td></tr></tbody></table>
<table><caption>Table B2</caption><thead><tr><th>Pixel wavelength (nm)</th><th>Count rate (counts/s)</th><th>Uncertainty (counts/s)</th></tr></thead><tbody><tr><td>94.2830</td><td>14.1491</td><td>0.171783</td></tr><tr><td>94.5460</td><td>14.0191</td><td>0.171024</td></tr><tr><td>94.8090</td><td>14.9100</td><td>0.176347</td></tr><tr><td>95.0720</td><td>16.3043</td><td>0.184384</td></tr><tr><td>95.3350</td><td>17.1000</td><td>0.188838</td></tr><tr><td>95.5980</td><td>17.5050</td><td>0.191043</td></tr><tr><td>95.8610</td><td>17.4376</td><td>0.190679</td></tr><tr><td>96.1240</td><td>17.1420</td><td>0.189056</td></tr><tr><td>96.3870</td><td>16.5653</td><td>0.185861</td></tr><tr><td>96.6500</td><td>15.2321</td><td>0.178244</td></tr><tr><td>96.9130</td><td>13.0265</td><td>0.164834</td></tr><tr><td>97.1760</td><td>10.5910</td><td>0.148648</td></tr><tr><td>97.4390</td><td>9.09842</td><td>0.137800</td></tr><tr><td>97.7020</td><td>8.63103</td><td>0.134226</td></tr><tr><td>97.9650</td><td>10.3757</td><td>0.147137</td></tr><tr><td>98.2280</td><td>12.2668</td><td>0.159983</td></tr><tr><td>98.4910</td><td>13.1883</td><td>0.165884</td></tr><tr><td>98.7540</td><td>13.0751</td><td>0.165136</td></tr><tr><td>99.0170</td><td>12.4840</td><td>0.161428</td></tr><tr><td>99.2800</td><td>12.8478</td><td>0.163724</td></tr><tr><td>99.5430</td><td>14.2184</td><td>0.172263</td></tr><tr><td>99.8060</td><td>16.6013</td><td>0.186083</td></tr><tr><td>100.069</td><td>17.9994</td><td>0.193750</td></tr><tr><td>100.332</td><td>18.2776</td><td>0.195256</td></tr><tr><td>100.595</td><td>18.1605</td><td>0.194622</td></tr><tr><td>100.858</td><td>17.4898</td><td>0.190986</td></tr><tr><td>101.121</td><td>17.8401</td><td>0.192897</td></tr><tr><td>101.384</td><td>16.7893</td><td>0.187152</td></tr><tr><td>101.647</td><td>16.4539</td><td>0.185276</td></tr><tr><td>101.910</td><td>15.5299</td><td>0.180037</td></tr><tr><td>102.173</td><td>14.9339</td><td>0.176543</td></tr><tr><td>102.436</td><td>13.8722</td><td>0.170184</td></tr><tr><td>102.699</td><td>12.7518</td><td>0.163140</td></tr><tr><td>102.962</td><td>13.6034</td><td>0.168493</td></tr><tr><td>103.225</td><td>14.3942</td><td>0.173343</td></tr><tr><td>103.488</td><td>14.6022</td><td>0.174565</td></tr><tr><td>103.751</td><td>15.7661</td><td>0.181382</td></tr><tr><td>104.014</td><td>18.2788</td><td>0.195278</td></tr><tr><td>104.277</td><td>21.0928</td><td>0.209766</td></tr><tr><td>104.540</td><td>22.9687</td><td>0.218839</td></tr><tr><td>104.803</td><td>23.3357</td><td>0.220617</td></tr><tr><td>105.066</td><td>23.4639</td><td>0.221226</td></tr><tr><td>105.329</td><td>23.6954</td><td>0.222283</td></tr></tbody></table>

*Continued*
<caption>Table B2</caption>

*Continued*

<table><thead><tr><td>Pixel wavelength (nm)</td><td>Count rate (counts/s)</td><td>Uncertainty (counts/s)</td></tr></thead><tbody><tr><td>105.592</td><td>23.2014</td><td>0.219957</td></tr><tr><td>105.855</td><td>22.8810</td><td>0.218412</td></tr><tr><td>106.118</td><td>22.0345</td><td>0.214361</td></tr><tr><td>106.381</td><td>21.7028</td><td>0.212745</td></tr><tr><td>106.644</td><td>21.9356</td><td>0.213864</td></tr><tr><td>106.907</td><td>22.9949</td><td>0.218958</td></tr><tr><td>107.170</td><td>23.0520</td><td>0.219236</td></tr><tr><td>107.433</td><td>23.4044</td><td>0.220892</td></tr><tr><td>107.696</td><td>24.7854</td><td>0.227313</td></tr><tr><td>107.959</td><td>25.9950</td><td>0.232784</td></tr><tr><td>108.222</td><td>26.2914</td><td>0.234123</td></tr><tr><td>108.485</td><td>24.8347</td><td>0.227542</td></tr><tr><td>108.748</td><td>23.5543</td><td>0.221608</td></tr><tr><td>109.011</td><td>24.4616</td><td>0.225818</td></tr><tr><td>109.274</td><td>26.1501</td><td>0.233473</td></tr><tr><td>109.537</td><td>27.1672</td><td>0.237993</td></tr><tr><td>109.800</td><td>27.8112</td><td>0.240776</td></tr><tr><td>110.063</td><td>28.4839</td><td>0.243688</td></tr><tr><td>110.326</td><td>29.1123</td><td>0.246345</td></tr><tr><td>110.589</td><td>29.5316</td><td>0.248127</td></tr><tr><td>110.852</td><td>28.6140</td><td>0.244239</td></tr><tr><td>111.115</td><td>28.3094</td><td>0.242938</td></tr><tr><td>111.378</td><td>28.2934</td><td>0.242867</td></tr><tr><td>111.641</td><td>28.9226</td><td>0.245551</td></tr><tr><td>111.904</td><td>29.2160</td><td>0.246785</td></tr><tr><td>112.167</td><td>28.3764</td><td>0.243233</td></tr><tr><td>112.430</td><td>27.6308</td><td>0.240027</td></tr><tr><td>112.693</td><td>26.8113</td><td>0.236447</td></tr><tr><td>112.956</td><td>26.9252</td><td>0.236942</td></tr><tr><td>113.219</td><td>27.7779</td><td>0.240677</td></tr><tr><td>113.482</td><td>29.9195</td><td>0.249774</td></tr><tr><td>113.745</td><td>30.5928</td><td>0.252556</td></tr><tr><td>114.008</td><td>30.9086</td><td>0.253868</td></tr><tr><td>114.271</td><td>31.4893</td><td>0.256225</td></tr><tr><td>114.534</td><td>31.3761</td><td>0.255767</td></tr><tr><td>114.797</td><td>32.0553</td><td>0.258518</td></tr><tr><td>115.060</td><td>32.6899</td><td>0.261074</td></tr><tr><td>115.323</td><td>33.2121</td><td>0.263169</td></tr><tr><td>115.586</td><td>33.2636</td><td>0.263391</td></tr><tr><td>115.849</td><td>33.5271</td><td>0.264485</td></tr><tr><td>116.112</td><td>33.2652</td><td>0.263531</td></tr><tr><td>116.375</td><td>33.2363</td><td>0.263573</td></tr><tr><td>116.638</td><td>33.7254</td><td>0.265745</td></tr></tbody></table>
<caption>Table B2</caption>

*Continued*

<table><thead><tr><th>Pixel wavelength (nm)</th><th>Count rate (counts/s)</th><th>Uncertainty (counts/s)</th></tr></thead><tbody><tr><td>116.901</td><td>33.1648</td><td>0.263935</td></tr><tr><td>117.164</td><td>31.6181</td><td>0.258719</td></tr><tr><td>117.427</td><td>31.1741</td><td>0.258535</td></tr><tr><td>117.690</td><td>31.0759</td><td>0.259950</td></tr><tr><td>117.953</td><td>29.9600</td><td>0.257011</td></tr><tr><td>118.216</td><td>30.6643</td><td>0.261132</td></tr><tr><td>118.479</td><td>32.0035</td><td>0.266927</td></tr><tr><td>118.742</td><td>33.1398</td><td>0.271937</td></tr><tr><td>119.005</td><td>34.0003</td><td>0.275741</td></tr><tr><td>119.268</td><td>33.8673</td><td>0.275575</td></tr><tr><td>119.531</td><td>33.6674</td><td>0.275260</td></tr><tr><td>119.794</td><td>33.0670</td><td>0.273322</td></tr><tr><td>120.057</td><td>32.7819</td><td>0.272614</td></tr><tr><td>120.320</td><td>31.5744</td><td>0.268370</td></tr><tr><td>120.583</td><td>31.0050</td><td>0.266365</td></tr><tr><td>120.846</td><td>30.2650</td><td>0.263861</td></tr><tr><td>121.109</td><td>29.1513</td><td>0.259791</td></tr><tr><td>121.372</td><td>29.4347</td><td>0.261240</td></tr><tr><td>121.635</td><td>30.2591</td><td>0.264633</td></tr><tr><td>121.898</td><td>30.2996</td><td>0.265124</td></tr><tr><td>122.161</td><td>30.4446</td><td>0.265803</td></tr><tr><td>122.424</td><td>31.0392</td><td>0.268330</td></tr><tr><td>122.687</td><td>33.2232</td><td>0.276762</td></tr><tr><td>122.950</td><td>35.0771</td><td>0.283509</td></tr><tr><td>123.213</td><td>35.4639</td><td>0.284663</td></tr><tr><td>123.476</td><td>36.0431</td><td>0.286191</td></tr><tr><td>123.739</td><td>36.7469</td><td>0.288013</td></tr><tr><td>124.002</td><td>37.0554</td><td>0.287915</td></tr><tr><td>124.265</td><td>37.9284</td><td>0.289418</td></tr><tr><td>124.528</td><td>38.3760</td><td>0.288825</td></tr><tr><td>124.791</td><td>38.6126</td><td>0.287643</td></tr><tr><td>125.054</td><td>39.0479</td><td>0.287681</td></tr><tr><td>125.317</td><td>39.2404</td><td>0.287545</td></tr><tr><td>125.580</td><td>38.6735</td><td>0.285188</td></tr><tr><td>125.843</td><td>39.1173</td><td>0.286532</td></tr><tr><td>126.106</td><td>39.5793</td><td>0.287968</td></tr><tr><td>126.369</td><td>39.2826</td><td>0.286721</td></tr><tr><td>126.632</td><td>39.0916</td><td>0.285903</td></tr><tr><td>126.895</td><td>39.5913</td><td>0.287621</td></tr><tr><td>127.158</td><td>40.1633</td><td>0.289583</td></tr><tr><td>127.421</td><td>40.0324</td><td>0.289081</td></tr><tr><td>127.684</td><td>40.0555</td><td>0.289126</td></tr><tr><td>127.947</td><td>40.2613</td><td>0.289808</td></tr></tbody></table>
<table><caption>Table B2</caption><thead><tr><th>Pixel wavelength (nm)</th><th>Count rate (counts/s)</th><th>Uncertainty (counts/s)</th></tr></thead><tbody><tr><td>128.210</td><td>39.9547</td><td>0.288668</td></tr><tr><td>128.473</td><td>40.1512</td><td>0.289381</td></tr><tr><td>128.736</td><td>39.2745</td><td>0.286176</td></tr><tr><td>128.999</td><td>38.7137</td><td>0.284113</td></tr><tr><td>129.262</td><td>38.2597</td><td>0.282436</td></tr><tr><td>129.525</td><td>38.3986</td><td>0.282942</td></tr><tr><td>129.788</td><td>38.2908</td><td>0.282520</td></tr><tr><td>130.051</td><td>38.4886</td><td>0.283257</td></tr><tr><td>130.314</td><td>38.1695</td><td>0.282090</td></tr><tr><td>130.577</td><td>37.7146</td><td>0.280392</td></tr><tr><td>130.840</td><td>37.1462</td><td>0.278263</td></tr><tr><td>131.103</td><td>37.0567</td><td>0.277920</td></tr><tr><td>131.366</td><td>37.3184</td><td>0.278902</td></tr><tr><td>131.629</td><td>37.1310</td><td>0.278193</td></tr><tr><td>131.892</td><td>37.0457</td><td>0.277865</td></tr><tr><td>132.155</td><td>37.0089</td><td>0.277748</td></tr><tr><td>132.418</td><td>37.7173</td><td>0.280384</td></tr><tr><td>132.681</td><td>37.6401</td><td>0.280090</td></tr><tr><td>132.944</td><td>36.9463</td><td>0.277522</td></tr><tr><td>133.207</td><td>36.8136</td><td>0.277005</td></tr><tr><td>133.470</td><td>36.5452</td><td>0.275985</td></tr><tr><td>133.733</td><td>35.7134</td><td>0.272837</td></tr><tr><td>133.996</td><td>35.3266</td><td>0.271354</td></tr><tr><td>134.259</td><td>34.9507</td><td>0.269910</td></tr><tr><td>134.522</td><td>34.8165</td><td>0.269379</td></tr><tr><td>134.785</td><td>34.6044</td><td>0.268564</td></tr><tr><td>135.048</td><td>34.8048</td><td>0.269347</td></tr><tr><td>135.311</td><td>35.1335</td><td>0.270617</td></tr><tr><td>135.574</td><td>34.2635</td><td>0.267252</td></tr><tr><td>135.837</td><td>34.2029</td><td>0.267016</td></tr><tr><td>136.100</td><td>33.3940</td><td>0.263828</td></tr><tr><td>136.363</td><td>33.8015</td><td>0.265427</td></tr><tr><td>136.626</td><td>33.1160</td><td>0.262731</td></tr><tr><td>136.889</td><td>33.4241</td><td>0.263951</td></tr><tr><td>137.152</td><td>32.4206</td><td>0.259958</td></tr><tr><td>137.415</td><td>31.4065</td><td>0.255860</td></tr><tr><td>137.678</td><td>31.8591</td><td>0.257711</td></tr><tr><td>137.941</td><td>31.0151</td><td>0.254261</td></tr><tr><td>138.204</td><td>30.3713</td><td>0.251609</td></tr><tr><td>138.467</td><td>30.3664</td><td>0.251592</td></tr><tr><td>138.730</td><td>29.9338</td><td>0.249792</td></tr><tr><td>138.993</td><td>29.6667</td><td>0.248677</td></tr><tr><td>139.256</td><td>30.0453</td><td>0.250243</td></tr></tbody></table>
<table><caption>Table B2</caption><thead><tr><th>Pixel wavelength (nm)</th><th>Count rate (counts/s)</th><th>Uncertainty (counts/s)</th></tr></thead><tbody><tr><td>139.519</td><td>29.5204</td><td>0.248065</td></tr><tr><td>139.782</td><td>29.3669</td><td>0.247417</td></tr><tr><td>140.045</td><td>28.6700</td><td>0.244488</td></tr><tr><td>140.308</td><td>27.9685</td><td>0.241460</td></tr><tr><td>140.571</td><td>27.1132</td><td>0.237747</td></tr><tr><td>140.834</td><td>26.7628</td><td>0.236199</td></tr><tr><td>141.097</td><td>26.8773</td><td>0.236713</td></tr><tr><td>141.360</td><td>26.5081</td><td>0.235075</td></tr><tr><td>141.623</td><td>25.9946</td><td>0.232803</td></tr><tr><td>141.886</td><td>26.1937</td><td>0.233686</td></tr><tr><td>142.149</td><td>26.2267</td><td>0.233816</td></tr><tr><td>142.412</td><td>26.8741</td><td>0.236685</td></tr><tr><td>142.675</td><td>26.3002</td><td>0.234160</td></tr><tr><td>142.938</td><td>26.4709</td><td>0.234900</td></tr><tr><td>143.201</td><td>26.3575</td><td>0.234400</td></tr><tr><td>143.464</td><td>26.2728</td><td>0.234021</td></tr><tr><td>143.727</td><td>26.1912</td><td>0.233668</td></tr><tr><td>143.990</td><td>26.0696</td><td>0.233129</td></tr><tr><td>144.253</td><td>25.7678</td><td>0.231775</td></tr><tr><td>144.516</td><td>25.6715</td><td>0.231316</td></tr><tr><td>144.779</td><td>25.7089</td><td>0.231494</td></tr><tr><td>145.042</td><td>25.1490</td><td>0.228958</td></tr><tr><td>145.305</td><td>25.4033</td><td>0.230121</td></tr><tr><td>145.568</td><td>24.7906</td><td>0.227332</td></tr><tr><td>145.831</td><td>25.0347</td><td>0.228455</td></tr><tr><td>146.094</td><td>24.7794</td><td>0.227284</td></tr><tr><td>146.357</td><td>24.7594</td><td>0.227179</td></tr><tr><td>146.620</td><td>24.5649</td><td>0.226289</td></tr><tr><td>146.883</td><td>24.3844</td><td>0.225453</td></tr><tr><td>147.146</td><td>24.2915</td><td>0.225029</td></tr><tr><td>147.409</td><td>23.9793</td><td>0.223578</td></tr><tr><td>147.672</td><td>23.3838</td><td>0.220794</td></tr><tr><td>147.935</td><td>23.3967</td><td>0.220843</td></tr><tr><td>148.198</td><td>22.8094</td><td>0.218084</td></tr><tr><td>148.461</td><td>22.8387</td><td>0.218204</td></tr><tr><td>148.724</td><td>22.6291</td><td>0.217187</td></tr><tr><td>148.987</td><td>22.0332</td><td>0.214320</td></tr><tr><td>149.250</td><td>21.6257</td><td>0.212347</td></tr><tr><td>149.513</td><td>21.6256</td><td>0.212326</td></tr><tr><td>149.776</td><td>21.5801</td><td>0.212112</td></tr><tr><td>150.039</td><td>21.0785</td><td>0.209642</td></tr><tr><td>150.302</td><td>20.5750</td><td>0.207101</td></tr></tbody></table>

*Continued*
<caption>Table B2</caption>

*Continued*

<table><thead><tr><th>Pixel wavelength (nm)</th><th>Count rate (counts/s)</th><th>Uncertainty (counts/s)</th></tr></thead><tbody><tr><td>150.565</td><td>20.5636</td><td>0.207048</td></tr><tr><td>150.828</td><td>19.7830</td><td>0.203090</td></tr><tr><td>151.091</td><td>20.0665</td><td>0.204538</td></tr><tr><td>151.354</td><td>19.8784</td><td>0.203571</td></tr><tr><td>151.617</td><td>19.7496</td><td>0.202919</td></tr><tr><td>151.880</td><td>18.9932</td><td>0.198988</td></tr><tr><td>152.143</td><td>18.5329</td><td>0.196585</td></tr><tr><td>152.406</td><td>17.8334</td><td>0.192829</td></tr><tr><td>152.669</td><td>17.7452</td><td>0.192356</td></tr><tr><td>152.932</td><td>17.3059</td><td>0.189961</td></tr><tr><td>153.195</td><td>17.2361</td><td>0.189560</td></tr><tr><td>153.458</td><td>16.4726</td><td>0.185323</td></tr><tr><td>153.721</td><td>16.6061</td><td>0.186083</td></tr><tr><td>153.984</td><td>16.2118</td><td>0.183842</td></tr><tr><td>154.247</td><td>15.8507</td><td>0.181788</td></tr><tr><td>154.510</td><td>15.7225</td><td>0.181046</td></tr><tr><td>154.773</td><td>15.0030</td><td>0.176863</td></tr><tr><td>155.036</td><td>14.5081</td><td>0.173918</td></tr><tr><td>155.299</td><td>14.0801</td><td>0.171341</td></tr><tr><td>155.562</td><td>13.8134</td><td>0.169712</td></tr><tr><td>155.825</td><td>13.3901</td><td>0.167083</td></tr><tr><td>156.088</td><td>13.2528</td><td>0.166236</td></tr><tr><td>156.351</td><td>12.1416</td><td>0.159126</td></tr><tr><td>156.614</td><td>11.6134</td><td>0.155624</td></tr><tr><td>156.877</td><td>11.3728</td><td>0.153984</td></tr><tr><td>157.140</td><td>10.9431</td><td>0.151067</td></tr><tr><td>157.403</td><td>10.4662</td><td>0.147741</td></tr><tr><td>157.666</td><td>10.0906</td><td>0.145057</td></tr><tr><td>157.929</td><td>9.92039</td><td>0.143841</td></tr><tr><td>158.192</td><td>9.61520</td><td>0.141590</td></tr><tr><td>158.455</td><td>9.65493</td><td>0.141896</td></tr><tr><td>158.718</td><td>9.60870</td><td>0.141544</td></tr><tr><td>158.981</td><td>9.06103</td><td>0.137453</td></tr><tr><td>159.244</td><td>8.95982</td><td>0.136693</td></tr><tr><td>159.507</td><td>8.74164</td><td>0.134999</td></tr><tr><td>159.770</td><td>8.61088</td><td>0.133983</td></tr><tr><td>160.033</td><td>8.30991</td><td>0.131630</td></tr><tr><td>160.296</td><td>7.85055</td><td>0.127917</td></tr><tr><td>160.559</td><td>7.58748</td><td>0.125779</td></tr><tr><td>160.822</td><td>7.27506</td><td>0.123146</td></tr><tr><td>161.085</td><td>7.25824</td><td>0.122987</td></tr><tr><td>161.348</td><td>6.45296</td><td>0.115958</td></tr></tbody></table>
<caption>Table B2</caption>

*Continued*

<table><thead><tr><td>Pixel wavelength (nm)</td><td>Count rate (counts/s)</td><td>Uncertainty (counts/s)</td></tr></thead><tbody><tr><td>161.611</td><td>6.01842</td><td>0.111997</td></tr><tr><td>161.874</td><td>5.52932</td><td>0.107347</td></tr><tr><td>162.137</td><td>4.93397</td><td>0.101401</td></tr><tr><td>162.400</td><td>4.63445</td><td>0.0982706</td></tr><tr><td>162.663</td><td>4.30224</td><td>0.0946943</td></tr><tr><td>162.926</td><td>4.00112</td><td>0.0913109</td></tr><tr><td>163.189</td><td>3.76594</td><td>0.0885845</td></tr><tr><td>163.452</td><td>3.38862</td><td>0.0840335</td></tr><tr><td>163.715</td><td>3.27268</td><td>0.0825747</td></tr><tr><td>163.978</td><td>3.17219</td><td>0.0813034</td></tr><tr><td>164.241</td><td>2.91522</td><td>0.0779512</td></tr><tr><td>164.504</td><td>2.79118</td><td>0.0762625</td></tr><tr><td>164.767</td><td>2.71778</td><td>0.0752600</td></tr><tr><td>165.030</td><td>2.57684</td><td>0.0732729</td></tr><tr><td>165.293</td><td>2.47660</td><td>0.0718372</td></tr><tr><td>165.556</td><td>2.49351</td><td>0.0720785</td></tr><tr><td>165.819</td><td>2.18285</td><td>0.0674434</td></tr><tr><td>166.082</td><td>2.16202</td><td>0.0671209</td></tr><tr><td>166.345</td><td>2.16178</td><td>0.0671209</td></tr><tr><td>166.608</td><td>2.07684</td><td>0.0657819</td></tr><tr><td>166.871</td><td>2.07195</td><td>0.0657159</td></tr><tr><td>167.134</td><td>1.94511</td><td>0.0636696</td></tr><tr><td>167.397</td><td>2.03726</td><td>0.0651521</td></tr><tr><td>167.660</td><td>1.92917</td><td>0.0633963</td></tr><tr><td>167.923</td><td>1.91410</td><td>0.0631563</td></tr><tr><td>168.186</td><td>1.94976</td><td>0.0637377</td></tr><tr><td>168.449</td><td>1.93750</td><td>0.0635331</td></tr><tr><td>168.712</td><td>1.93518</td><td>0.0634990</td></tr><tr><td>168.975</td><td>1.84351</td><td>0.0619770</td></tr><tr><td>169.238</td><td>1.90833</td><td>0.0630531</td></tr><tr><td>169.501</td><td>1.87452</td><td>0.0625000</td></tr><tr><td>169.764</td><td>1.90000</td><td>0.0629153</td></tr><tr><td>170.027</td><td>1.81851</td><td>0.0615554</td></tr><tr><td>170.290</td><td>1.81851</td><td>0.0615554</td></tr></tbody></table>

Data Availability Statement

The PHEBUS PDS4 data products used in the study are from BepiColombo PHEBUS Team (2022) and available at https://doi.org/10.21413/phebus-euv-mercury_11A_v0.1_latmos. The three observations of the first sequence correspond to the file: urn:esa:psa:bc_mpo_phebus: data_partialy_process ed: phe_par_sc_euvn_XODD_202110 09T013000_20211009T022300:0.1.

The three observations of the second sequence corresponds to the file: urn:esa:psa:bc_mpo_ phebus: data_partialy_process ed: phe_par_sc_euvn_XODD_20211009T233000_202110 10T002300:0.1.
Acknowledgments

The BepiColombo mission to explore Mercury is an international cooperation between the European Space Agency, ESA, and the Japan Aerospace Exploration Agency, JAXA. The PHEBUS project is funded by National Space Agencies of France (CNES), Japan and Russia (Roscosmos). The ground calibrations were supported by the Italian Space Agency under the contracts ASI-INAF I/022/10/0 and ASI-INAF 2017-47-H.O.

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