COS Legacy Archive Spectroscopic SurveY:
A Treasury of Star-Forming Galaxies
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Internal Collaboration Page
Co-Added Spectra
Updated 01.24.2021: Special care must be taken to co--add the multiple gratings, multiple--visit observations, and multiple CENWAVE settings of the CLASSY data. First, individual gratings are resampled to the lowest common resolution (Δλ) and combined, using a weighted average in regions of overlap. We use this process to produce datasets of different resolutions to meet different scientific needs:
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G130M / Highest Resolution Dataset - combines G130M spectra
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High--Resolution Dataset (HRD) -- combines G130M+G160M gratings
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Moderate--Resolution Dataset (MRD) -- combines G130M+G160M+G185M+G225M
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Low--Resolution Dataset (LRD) -- combines G130M+G160M+G140L (when available)
These spectra are shown as the resampled spectra below. Spectra were then binned by the largest common native resolution of the COS FUV+NUV instruments: 6 pixels. Final spectra are corrected for Galactic extinction using the map from Green+15 and are shifted into the rest-frame. These spectra are shown as the binned+galactic reddening corrected spectra below.
Resampled Spectra
Below we plot the MRD spectra of all observed G130M+G160M+G185M+ G225M gratings to date. The uncertainties of the individual gratings used in the co-add are shown by different colored shading. Note that there are some residual problems with the relative flux calibration between different gratings.
Binned+Galactic Reddening Corrected Spectra
Top: We plot the final co-added CLASSY spectra, where the binned HRD+error is shaded green and the binned MRD is plotted in black. For comparison, the resampled MRD+error is plotted in gray. Middle: The binned MRD smoothed by a Gaussian convolution with a kernel of 2 pixels to emphasize strong features. Signal-to-noise ratios are shown at several wavelengths (colored bars + number). Bottom: The signal-to-noise ratio of the binned HRD and MRD. Geocoronal Lya and OI features are masked out by white shading. In the top and middle panels, prominent nebular features are identified by red dashed lines and Milky Way ISM lines are denoted by light blue solid lines.
LyA Profiles
Interactive Spectrum
Interactive spectra for CLASSY galaxies are shown below. The coadded FUV spectra combine archival and new FUV G130M+G160M+G185M observations, whereas optical SDSS spectra are shown in the second plot. Note that chip gaps are indicated by blank spaces. You can look at any galaxy in the sample by selecting it from the Galaxy menu in the upper left. By zooming in on different regions of the spectrum, you will see different stellar, ISM, and nebular features. Most of the features can be identified by colored bands that display labels hovered over. You can click on the different types of spectral features in the legend to turn them on and off. Click the 'house' icon to reset the plot. Note that Geocoronal and Milky Way features are present.
Disclaimer: This is a preliminary version of this data and code and is subject to change. In particular, we are aware of the error in showing all line types and are working to fix it.