JuanCastillo29/space-mission-intelligence-data huggingface dataset:
If we assume a spherical projection of the nucleus, we can approximate the latitude range (within ± ∼10◦) from which dust and gas structures likely originated. For Fan A, this conversion corresponded to northern latitudes of ϕ ≃80◦N. For ease of comparison to the nucleus and other works, we will report both sky-projected and latitudinal position angles for the remainder of this paper. Due to solar radiation pressure (SRP), the dust in Fan A was blown in the anti-sunward direction by ρ≤5000 km and overlapped with the northern component of the cometary tail, which possibly contributed the diffuse nature of this structure (see left-most panel in Figure 4.)

[Figure: Figure 4: Maps with labelled fans. Left-most panel corresponds to 15 May 2021, where Fan A is present. Center panel corresponds to 21 August 2021, where Fans A and B are present. Right-most panel is 11 January 2022, where Fans C through F are present. Arrows share the same meanings as Figure 3.]

By the next epoch of data, 18 August 2021, the viewing geometry was much more favourable (∆= 0.85 au, geocentric distance). The comet filled the entire FoV, approximately 25000×25000 km. Due to this much closer perspective, further description and characterisation of the tail is limited to direction and relative intensity to adjacent structures. We can only report relative intensities of structures, or contrast, due to both the vastly different observational conditions epoch to epoch and the nature of MUSE as an IFU (difficult to photometrically calibrate). We will focus our remaining characterisation and analysis on dust fans and structures. Fan A persisted after 3 months of inbound evolution, however, the structure appeared to have significantly less contrast to the tail than in the 15 May sighting. Fan A extended linearly to around ρ=10000 km, within ±10◦of the 2015/2016 northern pole solution (still ϕ ≃80◦N). Outside of ρ=10000 km, the fan curved significantly in the anti-sunward direction and continued to contribute to the diffuse northern component of the tail (see middle panel of Figure 4). After 31 Au16 gust 2021, Fan A was increasingly hard to detect due to the very tight FoV (∼ 10000×10000 km by 30 September)
I. II. III.
IV. V. VI.
VII. VIII. IX.
X. XI. XII.

[Figure: Figure 6: Enhanced C2 maps corresponding to the 5125-5167 ˚A wavelength range, from 15 May 2021 to 09 March 2022. Red arrow denotes sky projection of the Northern pole orientation (2016 Rosetta solution). Lime arrow is the velocity vector. Yellow arrow is the Sun angle. North is up and East is left, denoted by white arrows. Concentric dashed rings denote projected cometocentric distance, ρ, as projected onto the sky, in units of 103 kilometres. Binning is 5×5.]
As seen in Figure 5, the first detection of red-doublet [OI] emissions were observed on 18 August 2021, between around 90◦from RFN (lower northern latitudes, ϕ ≃25◦N). This structure was diffuse, localised, and within ρ=5000 km from the comet. The next robust detection occurred 13 days later, on 31 August, still centred around 90◦(ϕ ≃25◦N). The structure was still diffuse, prohibiting precise position angle measurements. Despite this, the [OI] structure appeared to increase substantially to around ρ=10000 km from the nucleus, which is likely a product of better observing conditions and higher SNR. By 19 September, the [OI] signal had increased and consolidated to the SE quadrant, between 90 and 180◦(mid-southern latitudes). The southern migration of the [OI] signal persisted over 27 and 30 September, until the signal was nearly aligned with both reference frame South (RFS) and the 67P sky-projected South Pole (ϕ ≃-90◦S). Post-perihelion, the [OI] structure persisted for the first 3 epochs, from 11 January through 06 February 2022, however, it diminished in relative intensity and radial extent as time progressed. During this time, the [OI] signal was nearly parallel to the 67P sky-projected South pole, around 155◦from RFN (ϕ ≃-90◦S), similar to the last pre-perihelion observations. Another major molecule studied is the C2 radical. After careful dustsubtraction and rebinning procedures, we were able to extract robust C2 detections across almost the entire dataset. Similar to [OI], the first detection occurred on 18 August, where a strong preference for the North East quadrant and Eastern hemisphere was observed. From 18 August to 30 September, the C2 signal migrated southward, similar to the [OI] signal. By 30 September, the bulk component of C2 was centred around 120◦SE from RFN, and spanned ±80◦in both directions (mid southern latitudes, ϕ ≃-30 to -40◦S). Post-perihelion, the C2 signal had consolidated to the southern hemisphere and was centred approximately at the South Pole of 67P (ϕ ≃ -90◦S). Both C2 and [OI] shared closely aligned and rapidly changing trends over the apparition, thus defining the first major domain of coma evolution; (1) evolving gas structures.

I. II. III.
IV. V. VI.
VII. VIII. IX.
X. XI. XII.

[Figure: Figure 7: Enhanced NH2 maps corresponding to the 5973-5982 ˚A, 5991-6001 ˚A, and 6016-6026 ˚A wavelength ranges, from 15 May 2021 to 09 March 2022. Red arrow denotes sky projection of the Northern pole orientation (2016 Rosetta solution). Lime arrow is the velocity vector. Yellow arrow is the Sun angle. North is up and East is left, denoted by white arrows. Concentric dashed rings denote projected cometocentric distance, ρ, as projected onto the sky, in units of 103 kilometres. Binning is 3×3.]
green to red-doublet ratio for 67P, as seen in Figure 10. We estimated uncertainties from the original Gaussian fits. Larger uncertainties are observed at greater heliocentric distances due to the non-proportional subsidence of [OI] emissions versus contaminating NH2 emissions, where NH2 remains stronger for longer, therefore increasing contamination and uncertainty. The last G/R was computed around 1.7 au on 06 February, and constituted the furthest heliocentric distance probed. Naturally, this measurement has the largest uncertainty and likely occupies the upper range of the uncertainty interval, rather than a G/R ∼0.1. Despite these constraints, we retrieve several measurements around 0.1 pre-perihelion (0.13±0.05 to 0.07±0.02) and postperihelion (0.12±0.04). These are all consistent with a water-dominated coma.
3.3.2. Radial Haser Models Radial Haser models provide a framework for investigating the presence of extended sources in the coma. By fitting radial intensity profiles, it is possible to infer the contributions of primary sources (direct parent species sublimation from the nucleus) and extended sources (icy particles or dust) through comparing the fitted parent species scale lengths with the previously derived parent scale lengths in Fink et al. (1991); A’Hearn et al. (1995); Bannister et al. (2020). These extended sources can release gas over larger distances, altering the apparent morphology of the coma and impacting the size of the parent scale lengths.

NW NE

| SE SW |  |  |  |
| --- | --- | --- | --- |
|  |  |  |  |
|  | igure 11: Radial Ha anel depicts the un ensity profiles in th | s en e | er ha m |
I. II. III.
IV. V. VI.
VII. VIII. IX.
X. XI. XII.

[Figure: Figure 8: Enhanced CN maps corresponding to the 9138.16-9147.7 ˚A, 9165.18-9174.7 ˚A, and 9185.1-9194.76 ˚A wavelength ranges, from 15 May 2021 to 09 March 2022. Red arrow denotes sky projection of the Northern pole orientation (2016 Rosetta solution). Lime arrow is the velocity vector. Yellow arrow is the Sun angle. North is up and East is left, denoted by white arrows. Concentric dashed rings denote projected cometocentric distance, ρ, as projected onto the sky, in units of 103 kilometres. Binning ranged from 3×3 to 8×8 depending on the night.]
Unlike C2, the NH2 radical displayed a relatively stable morphology in the entire campaign. First detected in the North Eastern quadrant of 18 August, the NH2 structure was symmetric around the North Pole of 67P (20◦ from RFN), while the southern hemisphere lacked any clear NH2 signal after enhancement. From 31 August to 27 September, the NH2 structure slowly became asymmetric with respect to 67P’s North Pole. The NH2 signal had a noticeable counter-clockwise curvature of the main northern structure, and the appearance of a weaker southern component (first seen in (VI.) panel of Figure 7. By 30 September, the highly curved northern NH2 structure dominated the field, and the relatively less-intense southern NH2 structure displayed no obvious curvature in either direction. Notably, throughout this entire period, the base of the curved northern NH2 structure remained fixed at the North Pole of 67P (ϕ ≃90◦N), while the nascent southern structure appeared to radiate from near the South Pole of 67P. Similar to both [OI] and C2, the post-perihelion morphology of NH2 was consolidated to the southern hemisphere of our maps. However, unlike the previous molecules, the NH2 signal was spread across the entire hemisphere (opening angles ≤230◦), not consolidated into primarily one quadrant, and spread into the NW quadrant by 06 February. The CN radical was the final molecule we searched for in our datacubes, and was first detected on 18 August in the southern hemisphere around ∼175◦±20◦from RFN (South Pole, ϕ ≃-90◦S). Due to the observational and instrumental constraints discussed in subsection 2.2, we can only report general trends in CN morphology for most of the campaign, however, we have sufficient SNR to more robustly report observations around perihelion (30 September 2021 - 06 February 2022) and in the middle of the southern summer, when the CN signal was strongest. For most of the preperihelion CN detections, the signal was primarily focused in the southern hemisphere, around the South Pole. Notably, on 30 September, exceptional conditions and proximity to perihelion allowed for a higher SNR CN map to be extracted. Observed within this map is a narrow, curved CN structure centred around 135◦SE from RFN (mid-southern latitudes, ϕ ≃-45◦ S). Within ρ=5000 km, the structure is extremely narrow, linear, and focused, however, it expanded to fill almost the entire southern hemisphere outside of this range. The component outside of ρ=5000 km curved toward the anti-sunward direction and dominated the FoV from ∼110◦-300◦from RFN. Surprisingly, this CN structure was remarkably similar to the dust structure designated Fan B. Wary of possible dust contamination, we ran 25 tests to determine if any residual dust had been left in the CN maps postdust-subtraction, described in Appendix section Appendix B.
containing 26 slopes exceeding 15%/1000 ˚A.

[Figure: Figure 9: Spectral slope maps from 5000-7000 ˚A, normalised 6000 ˚A, and expressed in units of %/1000 ˚A. Pre-perihelion observations are presented across the top panels, postperihelion across the bottom panels. These dates were selected based on high signalto-noise, clear atmospheric conditions, low lunar illumination, and high lunar distance. Spectral slope values on the top axis are given in a 3000 km aperture.]

The coma was elongated in the West, corresponding to the anti-sunward tail. A central structure with slopes of 9-11%/1000 ˚A extended approximately 3000 km from the nucleus along this axis. Overall, the coma appeared relatively uniform, with no significant substructure aside from the western elongation. By 31 August, the coma exhibited a 2-3%/1000 ˚A bluer spectral slope globally and the extent of regions with higher spectral slopes had diminished significantly, despite a 1.2× smaller FoV. While still elongated along the western axis, a new coma structure correlating with the position of Fan B had appeared in the southeastern quadrant. This structure manifested as a ridge in the 11, 9, and 7 %/1000 ˚A contours and extended a few thousand kilometres to the SE. This trend continued into 30 September, where global spectral slopes were considerably lower, the extent of high slope regions (>11 %/1000 ˚A) were confined to the central thousand kilometres of the coma, and the structure synonymous with Fan B exhibited higher slopes further from the nucleus than surrounding regions, likely suggesting evidence of larger, longer living, or different compositions of dust particles in this region (see discussion in section 4).
applied a correction for atmospheric [OI] by subtracting the green and red-
doublet sky emissions from the 67P [OI] measurements.
Initially, we at-
tempted a direct subtraction of sky emission from the 67P emission; how-
ever, this approach resulted in an over-subtraction of the 5577.339 ˚A line,
leading to negative values in most of the dataset. Fortunately, the 5577.339
˚A emission from 67P was confined to the central few thousand kilometres
of the comet’s coma, leaving large portions of the datacube unaffected by
cometary emission. These comet-free regions provided an alternative sky-
observation for the green [OI] line, which significantly improved the accuracy
of the sky correction. We did not encounter similar problems with the sky
correction of the 6300.304 and 6363.776 ˚A [OI] lines, so we used the mea-
sured fluxes from the dedicated sky-observations.
After we propagated the atmospheric [OI] corrections, we computed the
al., 2015; Ciarniello et al., 2016; Filacchione et al., 2016; Fornasier et al., 2016), in which a strong orbital and seasonal dependences were found. These studies target different wavelength ranges from ∼4000 to 10000 ˚A, ground-based and in-situ. Nonetheless, the general trends are best described in Filacchione et al. (2020), across two win40 dows from 4000 to 5000 ˚A and 5000 to 8000 ˚A.

Generally, pre-perihelion, the nucleus exhibits a reddish colouration, dominated by carbon-rich particles and complex organics, while the coma is primarily populated by blue, icerich dust particles. As activity increases, more ice-rich particles fill the coma, creating an increasingly blue coma. As the comet nears perihelion, increased activity lifts the redder surface layers off the nucleus and into the coma, gradually reddening the coma. By perihelion, the nucleus is significantly bluer than the coma, which should be at its reddest. During the outbound trajectory, large red dust particles in the coma are replaced by smaller, bluer material lifted from the now-blue nucleus, transitioning the coma from red to blue. While our maps cannot probe the coma during the reddest perihelion stage, we do note similar pre-perihelion and post-perihelion bluening trends reported by the aforementioned studies. While phase-reddening is shown to cause significant colour deviations at high angles (> 50◦) (Bockel´ee-Morvan et al., 2019), it has negligible effects on our work (generally low phase angles, except 27 and 30 September). Further 2014-2016 in-situ and Earth-based studies report spectral slopes at comparable optical wavelengths, from 11-16%/1000 ˚Aaround perihelion, which are consistent with our results (8.2-18.4%/1000 ˚A) (Fornasier et al., 2015; Bertini et al., 2017; Opitom et al., 2020). We can further compare our spectral slopes with ground-based broadband colour determinations by Gardener et al. (2022), where their g−r and r−i measurements most closely represent our spectral slopes from 5000 to 7000 ˚A. Therein, Gardener et al. (2022) reports broadband colour measurements from the 2021 apparition which are consistent with a stable coma colour throughout perihelion (∼0.6 colour index g−r, ∼0.2 colour index r−i). However, these measurements have significant scatter (±0.2), which would hide any subtle trends around perihelion, like our gradual bluening (a few to several %/1000 ˚A). Additional recent studies from the 2021 apparition report higher spectral slopes of 15.2±4.1%/1000 ˚A (6 October 2021) in the spectral range 4450–6839 ˚A, and 14.2±0.4%/1000 ˚A (6 February 2022) in the same range (Ivanova et al., in prep.). Two of our measurements coincide with these reports, notably 30 September at 11.2%/1000 ˚A and 06 February at 8.3%/1000 ˚A. While we do not report uncertainties with our maps, an uncertainty of ±1-2%/1000 ˚A should be assumed in all of our slope measurements. These uncertainties are estimated by varying the spectral window we extract slopes from, and calculating the mean difference of the different fitted regions. Furthermore, the discrepancy is also due in part to the different spectral ranges 41
For the purpose of open access, the author has applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising from this submission. This analysis was based on observations collected at the European Southern Observatory under ESO programmes 105.2086.001 and 108.223B.001, and archival ESO programmes 096.C-0160(A) and 096.C-0855(B) taken by PI Aur´elie Guilbert-Lepoutre. This work was supported by the International Space Science Institute (ISSI) in Bern, through ISSI International Team project 504 “The Life Cycle of Comets”. The authors similarly wish to acknowledge the dedication and technical support of the support astronomers, Instrument Operators, and Telescope Operators at Paranal Observatory. For the purpose of open access, the authors have applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising from this submission.
In order to effectively model the transmission spectra using Molecfit, we identified regions of atmospheric gas emission and target gas emission, shown in Table A.4. The included wavelengths are regions in which atmospheric signature needs to be modelled and taken into account, while the excluded wavelengths are regions populated by non-atmospheric emission that the fitting software should not include. The excluded wavelengths are always regions within the larger included atmospheric windows. We used the standard atmospheric windows provided by the European Southern Observatory.

Table A.4: Atmospheric Wavelengths Modelled by Molecfit
Included Wavelengths ( ˚A) Excluded Wavelengths ( ˚A) 5876.5-5998.6 5976.2-5995.8 6453.5-6604.9 6534.3-6548.7 6864.6-7076.4 6918.7-6948.4
′′
6956.9-6977.0
′′
6994.0-7039.0 7160.1-7414.7 7244.1-7248.5
′′
7342.0-7354.3
′′
7367.5-7381.1 7676.5-7711.2 7681.8-7701.9 8133.4-8341.4 none 8945.2-9199.3 9138.3-9274.1 Notes. The Molecfit wavelengths regimes that it should include vs that it shouldn’t include. Exclusion is derived from gas emission (target not atmospheric) in the included wavelength ranges.
As mentioned in Subsection 3.1.2, we detect a strong correlation between dust Fan B and CN signal in the final pre-perihelion observation, 30 September 2021. We initially assumed dust contamination due to the near-perfect correlation between these features, so we sought to determine the spatial quality of the modelled dust-continuum we subtracted to make the maps. We implemented a chi-squared goodness of fit between the final shape- and slope-corrected reference dust spectrum with each input comet spectrum for the 30 September CN map. We created normalised chi-squared maps, shown in Figure B.13, where the best subtractions are represented by the darkest values, while deviations (over and under subtractions) are denoted by higher dust correction factors. We had to normalise by the lowest chi-squared value due to the intrinsic deviation from chi-squared = 1 caused by the residual gas emissions across the spectrum. By implementing this normalisation with the lowest chi-squared, we then standardise the maps to reflect deviations from our best subtraction, therefore highlighting any residual dust contamination.

Date: 2021-09-30T08:00:51.737
Dust Correction Factor
Figure B.13: Normalised chi-squared map to investigate any residual dust-continuum in the CN map from 30 September 2021. Bright regions correspond to large continuum deviations and poor fits, while darker regions represent good fits. The yellow cross is the cometary optocenter. Yellow arrow is the sunward angle. Green arrow is the positive velocity vector of the comet. Red arrow is the sky-projected North Pole of 67P.
Figure C.14: Two-dimensional decomposition of flux profile on 11 January 2022 using two Continuous Wavelet Transform (CWT) regimes. The upper panel represents the extracted profile with Voigt fit solutions, the second panel depicts the enhanced Polar image Voigt fit solutions, the third panel represents small-scale CWT of the profile, which highlighted fine sharp substructure within the coma, and used wavelet widths from 1-10. The lowest panel is the larger-scale CWT, which therefore highlighted broad wide structures in the coma, and used widths from 1-40. Both x-axes correspond to southern latitudes, with the South Pole represented by the cyan. The y-axes on the lower two panels denote the wavelet scale (widths). The dashed lines denote angles measured by Voigt fits for Fans C-F. Fans C and E are the orange dashed line. Fan D is the yellow dashed line. Fan f is the purple dashed line.
Nora H¨anni,1 Kathrin Altwegg,1 Michael Combi,2 Stephen A. Fuselier,3, 4 Johan De Keyser,5
Niels F. W. Ligterink,1, 6 Martin Rubin,1 and Susanne F. Wampfler7 1Physics Institute, Space Research & Planetary Sciences, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. 2Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, USA. 3Space Science Division, Southwest Research Institute, San Antonio, TX, USA. 4Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, TX, USA. 5Royal Belgian Institute for Space Aeronomy, BIRA-IASB, Brussels, Belgium. 6Faculty of Aerospace Engineering, Delft University of Technology, Delft, The Netherlands. 7Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, CH-3012 Bern, Switzerland.