About this Article
CLASSY HLSP Team - 2022 May 17
The COS Legacy Archive Spectroscopic SurveY (CLASSY) is a large treasury program that builds on the Hubble Space Telescope (HST) archive to construct the first high-quality, high-resolution far-ultra violet (far-UV) spectral database of nearby star-forming galaxies. The survey combines 177 orbits of archival observations with 135 new orbits (312 total orbits) of HST observations, or more than 600 total spectral images taken with the Cosmic Origins Spectrograph (COS). In order to understand the complex interplay between stars and gas in star forming galaxies, CLASSY focuses on six areas of important science:
- The science of massive stars
- Photoionization and chemical evolution modeling
- Reionization physics
- Lyman-α physics
- Feedback physics
- Far-UV nebular diagnostics.
As a result of these areas of study, CLASSY will provide enduring value and utility via state-of-the-art data products that will be provided to the astronomical community via MAST and the CLASSY HLSP (high-level science products) homepage.
The first CLASSY data release consists of the co-added COS data for all 45 galaxies covering ~1200-2000A. For each galaxy, CLASSY provides coadded spectra in four different resolutions:
- Very High Resolution Coadds (G130M spectra only)
- High Resolution Coadds (medium-resolution FUV gratings, or G130M+G160M spectra)
- Moderate Resolution (MR) Coadd (FUV+NUV medium resolution gratings, or G130M+G160M+G185M+G225M spectra)
- Low Resolution (LR) Coadds (combined medium and low resolution gratings such as G130M+G160M+G140L and G130M+G160M+G185M+G225M+G140L)
We provide simple tarball downloads of individual CLASSY HLSPs, as well as the entire CLASSY HLSP data collection.
In addition to full data access, the CLASSY HLSP homepage provides machine-readable table downloads for the tables of properties and interactive spectra that allow quick-look examination of the coadded spectral features, user-friendly jupyter notebook guides to accessing and using the CLASSY HLSPs, and important links such as to the NASA Astrophysics Database System (ADS) library of CLASSY publications.
Finally, to enable the community in accessing and exploring this spectral atlas, MAST have designed a dedicated CLASSY MAST portal. The CLASSY MAST portal will provide a unique search-and-selection method to access the CLASSY HLSPs, where users can select a subsample of the data products based on HLSP type, filename, or target properties such as coordinates or stellar mass. This search tool will continue to be developed based on the specifics of each HLSP release in order to allow more efficient and straightforward access to data products that are of interest to the user. This enables appropriate subsets of the CLASSY HLSPs to be easily selected for a given scientific analysis, to match specific survey sample properties, and more.