adsabs/AstroCLIMB huggingface dataset:
Paper: USmorph: An Updated Framework of Automatic Classification of Galaxy Morphologies and Its Application to Galaxies in the COSMOS Field
Authors: Jie Song, GuanWen Fang, Shuo Ba, Zesen Lin, Yizhou Gu, Chichun Zhou, Tao Wang, Cai-Na Hao, Guilin Liu, Hongxin Zhang, Yao Yao, Xu Kong
Figure caption: The proportion of different types of galaxies as a function of stellar mass, with different panels displaying the results at different redshifts bins (panel (a): 0.2 < z < 0.6; panel (b): 0.6 < z < 0.9; and panel (c): 0.9 < z < 1.2).
Paper: Deep Optical Emission-line Images of Nine Known and Three New Galactic Supernova Remnants
Authors: Robert A. Fesen, Marcel Drechsler, Xavier Strottner, Bray Falls, Yann Sainty, Nicolas Martino, Richard Galli, Mathew Ludgate, Markus Blauensteiner, Wolfgang Reich, Sean Walker, Dennis di Cicco, David Mittelman, Curtis Morgan, Aziz Ettahar Kaeouach, Justin Rupert, Zouhair Benkhaldoun
Figure caption: Enlargement of our [O III] image for the eastern region of G107.7-5.1.
Paper: Deep Optical Emission-line Images of Nine Known and Three New Galactic Supernova Remnants
Authors: Robert A. Fesen, Marcel Drechsler, Xavier Strottner, Bray Falls, Yann Sainty, Nicolas Martino, Richard Galli, Mathew Ludgate, Markus Blauensteiner, Wolfgang Reich, Sean Walker, Dennis di Cicco, David Mittelman, Curtis Morgan, Aziz Ettahar Kaeouach, Justin Rupert, Zouhair Benkhaldoun
Figure caption: [O III] and Hα images of SNR G209.9-8.2.
Paper: Deep Optical Emission-line Images of Nine Known and Three New Galactic Supernova Remnants
Authors: Robert A. Fesen, Marcel Drechsler, Xavier Strottner, Bray Falls, Yann Sainty, Nicolas Martino, Richard Galli, Mathew Ludgate, Markus Blauensteiner, Wolfgang Reich, Sean Walker, Dennis di Cicco, David Mittelman, Curtis Morgan, Aziz Ettahar Kaeouach, Justin Rupert, Zouhair Benkhaldoun
Figure caption: A color composite image of SNR G209.9-8.2. North is up, and east is to the left.
Paper: Deep Optical Emission-line Images of Nine Known and Three New Galactic Supernova Remnants
Authors: Robert A. Fesen, Marcel Drechsler, Xavier Strottner, Bray Falls, Yann Sainty, Nicolas Martino, Richard Galli, Mathew Ludgate, Markus Blauensteiner, Wolfgang Reich, Sean Walker, Dennis di Cicco, David Mittelman, Curtis Morgan, Aziz Ettahar Kaeouach, Justin Rupert, Zouhair Benkhaldoun
Figure caption: Top: IPHAS Hα image of G210.5+1.3. Bottom: MDM higher-resolution Hα images of the western and southeastern regions.
Paper: Deep Optical Emission-line Images of Nine Known and Three New Galactic Supernova Remnants
Authors: Robert A. Fesen, Marcel Drechsler, Xavier Strottner, Bray Falls, Yann Sainty, Nicolas Martino, Richard Galli, Mathew Ludgate, Markus Blauensteiner, Wolfgang Reich, Sean Walker, Dennis di Cicco, David Mittelman, Curtis Morgan, Aziz Ettahar Kaeouach, Justin Rupert, Zouhair Benkhaldoun
Figure caption: Color composite of Hα, [O III], and RGB images of the Nereides SNR G107.7-5.1.
Paper: Deep Optical Emission-line Images of Nine Known and Three New Galactic Supernova Remnants
Authors: Robert A. Fesen, Marcel Drechsler, Xavier Strottner, Bray Falls, Yann Sainty, Nicolas Martino, Richard Galli, Mathew Ludgate, Markus Blauensteiner, Wolfgang Reich, Sean Walker, Dennis di Cicco, David Mittelman, Curtis Morgan, Aziz Ettahar Kaeouach, Justin Rupert, Zouhair Benkhaldoun
Figure caption: Comparison of our Hα image of G209.9-8.2 vs. the VTSS Hα image.
Paper: Deep Optical Emission-line Images of Nine Known and Three New Galactic Supernova Remnants
Authors: Robert A. Fesen, Marcel Drechsler, Xavier Strottner, Bray Falls, Yann Sainty, Nicolas Martino, Richard Galli, Mathew Ludgate, Markus Blauensteiner, Wolfgang Reich, Sean Walker, Dennis di Cicco, David Mittelman, Curtis Morgan, Aziz Ettahar Kaeouach, Justin Rupert, Zouhair Benkhaldoun
Figure caption: Enlargement of our [O III] image for the western region of G107.7-5.1.
Paper: Deep Optical Emission-line Images of Nine Known and Three New Galactic Supernova Remnants
Authors: Robert A. Fesen, Marcel Drechsler, Xavier Strottner, Bray Falls, Yann Sainty, Nicolas Martino, Richard Galli, Mathew Ludgate, Markus Blauensteiner, Wolfgang Reich, Sean Walker, Dennis di Cicco, David Mittelman, Curtis Morgan, Aziz Ettahar Kaeouach, Justin Rupert, Zouhair Benkhaldoun
Figure caption: Color Hα and [O III] composite images of G210.5+1.3 with and without stars. North is up, and east is to the left.
Paper: Deep Optical Emission-line Images of Nine Known and Three New Galactic Supernova Remnants
Authors: Robert A. Fesen, Marcel Drechsler, Xavier Strottner, Bray Falls, Yann Sainty, Nicolas Martino, Richard Galli, Mathew Ludgate, Markus Blauensteiner, Wolfgang Reich, Sean Walker, Dennis di Cicco, David Mittelman, Curtis Morgan, Aziz Ettahar Kaeouach, Justin Rupert, Zouhair Benkhaldoun
Figure caption: Hα and [O III] images of G210.5+1.3. North is up, and east is to the left.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: Distribution of the S/N Gaia XP coefficients for the sample, for the BP portion of the spectrum (shown on the left) and for the RP portion of the spectrum (on the right). The black dashed histograms represent the sample’s distribution when the S/N is averaged across all 55 coefficients in BP and RP. The blue and red histograms show the analogous distributions considering only the first 10 coefficients and the remaining higher-order coefficients, respectively. The vertical lines of different colors represent the S/N thresholds employed in our training sample. Specifically, we consider spectra with S/N values greater than 100 for both BP and RP first-order coefficients (1–10), while for coefficients 11–55, an S/N threshold of 1 is applied.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: AspGap training set for this application, taken from SDSS APOGEE DR17. The left panel shows the T eff–﹩\mathrm{log}\,g﹩ Kiel diagram of the training data, color coded by [M/H]. The right panel shows the number density distribution of the [M/H]–[α/M] abundance diagnostics in the training set. AspGap is designed to estimate T eff, ﹩\mathrm{log}\,g﹩, [M/H], and [α/M] values from XP spectra that are consistent with the SDSS APOGEE training data.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: Three astrophysical validation tests for the quality of the AspGap-based [α/M] estimates in the metal-poor regime. All three validations are based on the idea that in some regimes the spatial or kinematic selection of stars leads to clear (externally derived) expectations for p([α/M]) in a given [M/H] regime. Top left: validation using the “poor old heart” of the Milky Way (Rix et al. 2022), showing the fraction of high-[α/M]XP stars as a function of R apo and eccentricity for stars with [M/H]XP < −1.1. At high eccentricities (>0.75) and large R apo (>10 kpc) the population should be dominated by the GES population, known to be low-α (Helmi et al. 2018; Hasselquist et al. 2021); this is exactly what our [α/M]XP values show. Top right: distribution of stars on the [M/H]–[α/M] plane that have been selected (purely kinematically) as likely GES members, expected to lie below the (black dashed) high-α vs. low-α dividing line in the diagram. The stars with AspGap-determined [M/H] and [α/M] labels (colored density) lie in the expected position, and also agree with APOGEE (green points); this latter coincidence is not a trivial consequence of the training, given that these stars are a tiny and unusual subsample. Bottom: validation in LMC, using a similar [M/H]–[α/M] diagonal diagram to that of the top right panel. The stars with AspGap-determined labels (colored density) lie at low [α/M], as expected for the LMC (Russell & Dopita 1992); they again agree with the APOGEE labels for this peculiar subset.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: Comparison between AspGap-derived labels and those from three different ground-based survey data sets: LAMOST-LRS, LAMOST-MRS, and GALAH. Each column corresponds to a specific parameter: T eff, ﹩\mathrm{log}\,g﹩, [M/H], or [α/M]. The top panel represents the comparison with Gaia XP (AspGap) and LAMOST-LRS (SLAM), color coded by the number density. The middle panel showcases the comparison with the LAMOST-MRS data set (Cycle-StarNet), and the bottom panel depicts the comparison with GALAH DR3. In each panel, the scatter and the median bias for each stellar label are marked. The black dotted line represents the one-to-one line, reflecting perfect agreement between the surveys. The pairs of gray dashed lines in the plots represent the deviation of 1σ in the difference between the compared labels.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: Astrophysical validation of AspGap's [α/M] determinations, based on the fact that—at a given [M/H]—the α-enhanced (or thick) disk has more vertical motions (e.g., Bovy et al. 2012). The left panel illustrates the relationship between the rms vertical action J  z  (quantifying the vertical kinematics) and the AspGap-derived [α/M] in two narrow bins of [M/H], −0.7 < [M/H] < −0.5 (red) and −0.5 < [M/H] < −0.3 (blue). The solid line with circles shows the result of AspGap labels, while the dashed lines with triangles represent those from APOGEE for reference. The AspGap results show the expected trend that agrees quite closely with that seen in APOGEE data; subtle offsets may simply reflect the different spatial selection function of the sample. The right panel shows a related astrophysical validation test, based on the known fact that—again at a given [M/H]—the α-enhanced disk is much more centrally concentrated (e.g., Bovy et al. 2016). The panel displays the mean angular momentum L  z  as a function of [α/M] in the same two [M/H] bins, again showing the expected trend and good agreement with APOGEE.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: Comparison of the stellar labels T eff, ﹩\mathrm{log}\,g﹩, and [M/H] (left to right) derived from essentially the same XP data but with two different approaches, AspGap and XGBoost as implemented by A23. (Note that A23 also used bandpass magnitudes derived from spectra and additional external photometry, such as that from the Wide-field Infrared Survey Explorer.) The diagrams are color coded by the logarithmic sample number density. The first row of panels represents the comparison for the entire crossmatched RGB sample, consisting of 10,825,736 stars. In the second row, the comparison is restricted to the subset of stars with an S/N of RP coefficients higher than 1000, comprising 917,921 stars.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: Comparison between literature [Fe/H], AspGap [M/H], and APOGEE Data Release 16 [M/H] for open clusters. We compare the AspGap [M/H] and the [Fe/H] in Donor et al. (2020), with 1σ as the error bar in the left panel. In the right panel, all cluster samples crossmatched with literature are denoted as blue circles, and clusters with more than three identified members in APOGEE are denoted as red triangles. The marker size indicates the number of members in each cluster, and the metallicity difference  Δ[M/H] > 0.2 is shown by the gray shaded areas.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: Histograms of G magnitude and errors of stellar parameters. From left to right, the histograms represent the G magnitude, ﹩{\sigma }_{{T}_{\mathrm{eff}}}﹩, ﹩{\sigma }_{\mathrm{log}\,g}﹩, σ [M/H], and σ [α/M] distributions. The black color represents the compiled data of 37 million RGB stars. A subset, comprising 14 million stars with available radial velocity measurements from Gaia, is also included.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: Left: selected stars classified into low-[α/M] and high-[α/M] groups with −0.9 < [M/H] < 0, representing the ground truth from APOGEE. Right: confusion matrix showing the Gaia XP–predicted low/high-[α/M] groups of APOGEE.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: The comparison of the T eff, ﹩\mathrm{log}\,g﹩, and [M/H] parameters, divided into different Galactic latitudes (b), from left to right. The top panel corresponds to stars with ∣b∣ < 10, while the bottom panel represents stars with ∣b∣ > 30. The comparison is made using the crossmatched catalog with A23's RGB sample.
Paper: Variations of Heavy Ions in Interplanetary Shock Driven by Interplanetary Coronal Mass Ejections and Stream Interaction Regions
Authors: Cong Wang, Qian Ye, Mu Li, Fei He, Xiaoxin Zhang
Figure caption: Schematic diagram of the change of ion abundance ratio before and after shocks in different solar activity cycles. The time interval used in the SEA is 2 hr. (a) The temporal variation of He2+ abundance, (b) the temporal variation of C6+/O4+ ratio, (c) the temporal variation of C6+/O5+ ratio, and (d) the temporal variation of O7+/O6+ ratio. The label “0h” denotes the initiation of shocks.
Paper: Variations of Heavy Ions in Interplanetary Shock Driven by Interplanetary Coronal Mass Ejections and Stream Interaction Regions
Authors: Cong Wang, Qian Ye, Mu Li, Fei He, Xiaoxin Zhang
Figure caption: Solar wind characteristics of shock events. The size of the circles in the left panel corresponds to the magnetosonic Mach number of the event. The red dots represent shock events driven by ICMEs, while the blue dots represent shock events driven by SIRs (stream interaction regions). In the right panel, the color red indicates ICME-driven shock events, and the color blue indicates SIR-driven shock events.
Paper: Variations of Heavy Ions in Interplanetary Shock Driven by Interplanetary Coronal Mass Ejections and Stream Interaction Regions
Authors: Cong Wang, Qian Ye, Mu Li, Fei He, Xiaoxin Zhang
Figure caption: Elemental composition of shocks in different years compared to the mean value of all events. Events at the solar maximum are indicated in red, events at the solar minimum are indicated in blue, and events in years other than minimums and maximums are indicated in yellow. 〈X/O〉 denotes the ratio between elemental composition (He, C, Ne, Mg, Si, and Fe, respectively, from left to right) in different solar phases. 〈X/O〉mean denotes the average values during the whole period.
Paper: Variations of Heavy Ions in Interplanetary Shock Driven by Interplanetary Coronal Mass Ejections and Stream Interaction Regions
Authors: Cong Wang, Qian Ye, Mu Li, Fei He, Xiaoxin Zhang
Figure caption: Variations in abundance ratios of different ions relative to oxygen. The time interval used in the SEA is 2 hr. The first vertical red line indicates the initiation of shocks. The second vertical red line indicates the end of the ICME. The red and blue shades denote the error term.
Paper: Variations of Heavy Ions in Interplanetary Shock Driven by Interplanetary Coronal Mass Ejections and Stream Interaction Regions
Authors: Cong Wang, Qian Ye, Mu Li, Fei He, Xiaoxin Zhang
Figure caption: Schematic diagram of the change of ion abundance ratio before and after shocks. The time interval used in the SEA is 2 hr. The first vertical red line indicates the initiation of shocks. The second vertical red line indicates the end of the ICME. The red and blue shades denote the error term. The shaded region in the figure represents the error, which is calculated based on the uncertainties listed in the data set. It is noteworthy that the error associated with He2+ abundance is on the order of 10−4, making it challenging to visualize effectively in the figure.
Paper: Variations of Heavy Ions in Interplanetary Shock Driven by Interplanetary Coronal Mass Ejections and Stream Interaction Regions
Authors: Cong Wang, Qian Ye, Mu Li, Fei He, Xiaoxin Zhang
Figure caption: Variations in abundance ratios of different ions relative to oxygen in different solar activity cycles. The time interval used in the SEA is 2 hr. (a) The temporal variation of He/O ratio, (b) the temporal variation of C/O ratio, (c) the temporal variation of Ne/O ratio, (d) the temporal variation of Mg/O ratio, (e) the temporal variation of Si/O ratio, and (f) the temporal variation of Fe/O ratio. The label “0h” denotes the initiation of shocks.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: The architecture of the AspGap model, consisting of four blocks: a pretrained APOGEE decoder that takes APOGEE(-like) spectra to generate predictions for stellar labels; an XP encoder that generates 1024 shared latent variables from the 2 × 55 XP coefficients; the hallucinator, which generates APOGEE-like spectra from these embedded variables to be fed into the pretrained APOGEE decoder; and an XP decoder that generates stellar label predictions from the XP encoder’s 1024 latent variables. During the training process, both sets of stellar label predictions, obtained from the XP decoder and the hallucinator/APOGEE decoder, are utilized in the objective function of AspGap. The fundamental concept behind the design of AspGap is the prospect that incorporating the stellar label generation through the hallucinator route will lead to a more robust and physically meaningful XP encoder following the training phase. In the testing phase and for inference on other data, we only use the labels generated by the XP decoder. This is because, once the model is well trained, the mean-square error between the hallucinator's predictions and the ground truth and that between the XP decoder’s predictions and the ground truth become approximately the same.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: Validation of AspGap-derived labels from Gaia XP spectra (XP) vs. APOGEE labels (AP). From left to right, the panels show the results of twofold cross-validation drawn from the training set for T eff, ﹩\mathrm{log}\,g﹩, [M/H], and [α/M]. The (small) scatter and (negligible) bias are indicated in each panel, and η is defined as the outlier rate given by Equation (5). The pairs of dashed lines indicate the 1σ deviation in the difference between the compared labels. The color denotes the logarithm of the number density.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: Quality of the labels generated by AspGap, as a function of the input XP spectra’s S/N and G-band magnitude, shown for T eff, ﹩\mathrm{log}\,g﹩, [M/H], and [α/M] from left to right. In all panels, the solid black curves denote the formal errors generated by AspGap. The teal, green, orange, and red lines denote the cross-validation values for different measures of precision and accuracy: the rms deviation (RMSE), the median absolute error (MAE), the scatter (standard deviation), and the bias, respectively. The thin dashed line indicates the naive 1/(S/N) expectation. The top row shows this as a function of the BP S/N, the middle row as a function of the RP S/N. The cross-validation results approximately follow the S/N-scaling expectations for T eff, ﹩\mathrm{log}\,g﹩, and [M/H], but less so for [α/M].
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: Definition of the RGB sample for which the AspGap label estimates are most precise and robust. The sample cuts are illustrated in the H-R diagram (color coded by the number density of the Gaia XP sample) with two conditions T eff < 5300 K and ﹩\varpi \cdot {10}^{G/5}\lt {10}^{(-0.003{T}_{\mathrm{eff}}+19)/5\,+\,10}﹩, where the pseudoluminosity (y-axis) in the second cut is chosen to remain well defined even for ϖ ≤ 0. They lead to a sample of 37 million objects.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: Summary of the stellar labels derived via AspGap for the ∼37 million members of the RGB catalog (see Figure 9). Left: T eff–﹩\mathrm{log}\,g﹩ diagram color coded by [M/H]. Right: [M/H]–[α/M] abundance diagnostic diagram color coded by logarithmic density.
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: Fidelity of the label uncertainty estimates. The panels show the probability density distribution of the uncertainty-normalized differences (χ) between AspGap and APOGEE labels. In each panel, the blue dashed curve represents the standard normal distribution ﹩{ \mathcal N }(0,1)﹩, and the orange solid line denotes the best-fitting normal distribution of χ. The formal uncertainties are meaningful—also for [α/M]—but about 30% underestimated. By conducting these validations, we gain access to the ground truth labels, which allows us to evaluate various performance metrics such as the MAE (χ).
Paper: AspGap: Augmented Stellar Parameters and Abundances for 37 Million Red Giant Branch Stars from Gaia XP Low-resolution Spectra
Authors: Jiadong Li, 佳东 李, Kaze W. K. Wong, David W. Hogg, Hans-Walter Rix, Vedant Chandra
Figure caption: Example of a predicted APOGEE-like gradient spectrum produced inside the hallucinator, compared to an actual APOGEE gradient spectrum. During training, the hallucinator predictions are not directly compared to real APOGEE spectra. Rather, the hallucinated spectra only need to produce the correct stellar labels when fed into the pretrained APOGEE pipeline decoder. This allows the hallucinator to learn a mapping that captures relevant spectral features correlated with the stellar labels.