Mission Overview
Lyman-alpha Reference Sample (LARS)
Primary Investigators: Jens Melinder, Matthew Hayes, Göran Östlin
HLSP Authors: Jens Melinder
Released: 2023-07-24
Updated: 2023-07-24
Primary Reference(s): Melinder, et al. 2023
DOI: 10.17909/pbe1-m743
Citations: Melinder, et al. 2023 metrics
Source Data:
Slideshow
Color RGB composites of selected LARS galaxies. The stellar continuum (left panel) is derived from HST I-, B-, and U-band images (red, green, and blue channels, respectively). The right panel shows the emission in Hα (red), Lyα (blue), and stellar continuum in the FUV near Ly-α (green). The scale bar (lower left) has a length of 5 kpc.
Color RGB composites of selected LARS galaxies. The stellar continuum (left panel) is derived from HST I-, B-, and U-band images (red, green, and blue channels, respectively). The right panel shows the emission in Hα (red), Lyα (blue), and stellar continuum in the FUV near Ly-α (green). The scale bar (lower left) has a length of 5 kpc.
Color RGB composites of selected LARS galaxies. The stellar continuum (left panel) is derived from HST I-, B-, and U-band images (red, green, and blue channels, respectively). The right panel shows the emission in Hα (red), Lyα (blue), and stellar continuum in the FUV near Ly-α (green). The scale bar (lower left) has a length of 5 kpc.
Color RGB composites of selected LARS galaxies. The stellar continuum (left panel) is derived from HST I-, B-, and U-band images (red, green, and blue channels, respectively). The right panel shows the emission in Hα (red), Lyα (blue), and stellar continuum in the FUV near Ly-α (green). The scale bar (lower right) has a length of 5 kpc.
Color RGB composites of selected LARS galaxies. The stellar continuum (left panel) is derived from HST I-, B-, and U-band images (red, green, and blue channels, respectively). The right panel shows the emission in Hα (red), Lyα (blue), and stellar continuum in the FUV near Ly-α (green). The scale bar (lower left) has a length of 5 kpc.
Color RGB composites of selected LARS galaxies. The stellar continuum (left panel) is derived from HST I-, B-, and U-band images (red, green, and blue channels, respectively). The right panel shows the emission in Hα (red), Lyα (blue), and stellar continuum in the FUV near Ly-α (green). The scale bar (lower left) has a length of 5 kpc.
Color RGB composites of selected LARS galaxies. The stellar continuum (left panel) is derived from HST I-, B-, and U-band images (red, green, and blue channels, respectively). The right panel shows the emission in Hα (red), Lyα (blue), and stellar continuum in the FUV near Ly-α (green). The scale bar (lower left) has a length of 5 kpc.
Color RGB composites of selected LARS galaxies. The stellar continuum (left panel) is derived from HST I-, B-, and U-band images (red, green, and blue channels, respectively). The right panel shows the emission in Hα (red), Lyα (blue), and stellar continuum in the FUV near Ly-α (green). The scale bar (lower left) has a length of 5 kpc.
Overview
The Lyman-α Reference Sample (hereafter, LARS) collection consists of HST observations of 45 star-forming galaxies at redshifts 0.03–0.24. The products consist of reduced images, line and galaxy property maps, and tables of photometric measurements. The data used mainly come from the two LARS HST imaging programs (PIDs: 12310 and 13483). Various instruments (ACS/SBC, ACS/WFC, and WFC3/UVIS) and filters have been used to image the Lyman-α/Hα/Hβ emission and characterize the stellar populations. Apart from the reduced images the collection also contains maps of emission lines and of derived physical quantities such as stellar age, extinction, and mass for the galaxies. In addition the collection contains tables with global photometry of the galaxies and tables with surface brightness profiles for each galaxy.
Data Products
Data file naming convention:
hlsp_lars_hst_<instrument>_<targ>_<filter>_v1.0_<prodType>.<ext>
where:
- <Instrument> is the name of the instrument/mode used for the observations, one of acs, acs-sbc, acs-wfc, wfc3, wfc3-uvis or a combination of these
- <targ> is the LARS target identifier, such as elars01 or lars08
- <filter> is the name of the filter used, such as: f125lp, f140lp, f150lp, f336w, f502n, f673n, f775w
- <prodType> is the type of semantic content of the product (see below)
- <ext> is the file extension type: one of fits (science) or png (previews)
Semantic content types:
| drz | Drizzle-combined science image |
| map | Spatial map of physical quantities |
| preview | Preview (RGB) image |
| tab | Tables of photometric and physical quantities per target, as well as surface brightness profiles |
Attributes of the images, maps, and tables of measurements are summarized below; consult the README and Melinder et al. (2023) for details of how the contents were prepared.
Image Files
The calibrated input images from this survey were drizzle-combined, and the output images were sampled at a common scale of 0.04 arcsec/pix, aligned to a common image coordinate frame, and PSF-matched. Binned images were created using a Voronoi tesselation method with a limiting signal-to-noise ratio (SNR) of 10, and a maximum size of 1 arcsec2 (i.e., 252 pixels). The bluest stellar continuum filter was used to determine the binning pattern. Each FITS file contains 4 image extensions, with EXTNAME values as follows:
| EXTNAME | Description |
|---|---|
| SCI | Science image |
| WHT | Weight array for science image |
| SCI-BINNED | Binned science image |
| WHT-BINNED | Binned weight array |
| PROVENANCE | Provenance of the images, i.e., which input data contributed to the final product |
MAP Files
The map files include images of stellar continuum, as well as continuum- and background-subtracted line emission, and spatial distributions of derived physical quantities such as the star formation rate. Each FITS file contains 20 image extensions, distinguished by the EXTNAME keyword value. Extension numbers 1 through 10 are images of the physical quantities, and 11 through 20 are the corresponding standard-deviations of those quantities.
Table File
The table contains measurements of various physical quantities for each target. The FITS file is organized into 47 BINTABLE extensions, which are identified by the value of the EXTNAME keyword. The first extension is a table of global quantities (i.e., averaged over each galaxy), extensions 2 through 46 are radially-averaged profiles of these quantities for each galaxy, and the last extension is the PROVENANCE for these quantities.
Data Access
LARS images are available in the MAST Portal (web-based, cross-mission search interface) and Astroquery (Python package to search for and download files from Python scripts you write), and via the direct download table below. The maps and the measurements table are only available from the Direct Downloads section below. Set the Provenance Name filter to LARS in the Portal Advanced Search to find all or individual images.
from astroquery.mast import Observations
all_obs = Observations.query_criteria(provenance_name="LARS")
data_products = Observations.get_product_list(all_obs)
Observations.download_products(data_products)
-
A web-based interface for cross-mission searches of data at MAST or the Virtual Observatory
-
Search for and retrieve GLASS-JWST data products programmatically.
Direct Download
Access g-zipped tar files of the LARS images, maps, and previews from the table below, by target. The file sizes are between 76 and 130 MB. The measurements table file hlsp_lars_hst_wfc3-acs_multi_v1.0_tab.fits is also available.
| LARS ID | SDSS ID | Common Name | Files |
|---|---|---|---|
| LARS 01 | SDSS-J132844.05+435550.5 | Mrk 259 | |
|
LARS 02 |
SDSS-J090704.88+532656.6 | Shoc 240 | |
|
LARS 03 |
SDSS-J131535.06+620728.6 | Arp 238 | |
|
LARS 04 |
SDSS-J130728.45+542652.3 | ||
|
LARS 05 |
SDSS J135950.92+572622.9 | Mrk 1486 | |
|
LARS 06 |
SDSS-J154544.52+441551.8 | KISSR 2019 | |
| LARS 07 | SDSS-J131603.91+292254.0 | IRAS F13136+2938 | |
| LARS 08 | SDSS-J125013.50+073441.5 | ||
| LARS 09 | SDSS-J082354.96+280621.6 | IRAS 08208+2816 | |
| LARS 10 | SDSS-J130141.52+292252.8 | Mrk 0061 | |
| LARS 11 | SDSS-J140347.22+062812.1 | ||
| LARS 12 | SDSS J093813.44+542824.9 | LEDA 27453 | |
| LARS 13 | SDSS-J015028.39+130858.4 | IRAS 01477+1254 | |
| LARS 14 | SDSS-J092600.41+442736.1 | ||
| ELARS 01 | SDSS-J161140.81+522727.0 | NGC 6090 | hlsp_lars_hst_multi_elars01_v1.0_allfiles.tgz |
| ELARS 02 | SDSS-J132109.07+590605.3 | Mrk 65 | |
| ELARS 03 | SDSS-J114511.42+614230.6 | UGC 06727 | |
| ELARS 04 | SDSS-J172823.84+573243.4 | NGC 6387 | |
| ELARS 05 | SDSS-J110501.98+594103.5 | SBS 1102+599A | |
| ELARS 06 | SDSS-J115840.58+645753.0 | ||
| ELARS 07 | SDSS-J101242.97+613302.8 | ||
| ELARS 08 | SDSS-J103020.91+611549.3 | ||
| ELARS 09 | SDSS-J132734.70+664516.6 | ||
| ELARS 10 | SDSS-J110504.41+593957.3 | SBS 1102+599B | |
|
ELARS 11 |
SDSS-J092715.48+583654.4 | MRK 1417 | |
|
ELARS 12 |
SDSS-J130607.16+591302.4 | SBS 1304+594 | |
|
ELARS 13 |
SDSS-J105100.65+655940.5 | VII Zw 348 | |
|
ELARS 14 |
SDSS-J112722.07+604454.1 | SBS 1124+610 | |
|
ELARS 15 |
SDSS-J134437.82+611424.3 | MCG +10-20-017 | |
|
ELARS 16 |
SDSS-J135209.13+560631.4 | ||
|
ELARS 17 |
SDSS-J102656.29+584941.6 | ||
|
ELARS 18 |
SDSS-J152053.59+571122.1 | ||
|
ELARS 19 |
SDSS-J120506.35+563330.9 | ||
|
ELARS 20 |
SDSS-J133858.25+614957.6 | ||
|
ELARS 21 |
SDSS-J141911.37+654946.3 | ||
|
ELARS 22 |
SDSS-J170912.73+604950.0 | SBS 1708+608 | |
|
ELARS 23 |
SDSS-J144827.20+630210.4 | ||
|
ELARS 24 |
SDSS-J144305.31+611838.6 | ||
|
ELARS 25 |
SDSS-J101201.93+603720.3 | KUG 1008+608 | |
|
ELARS 26 |
SDSS-J115241.69+661827.2 | ||
|
ELARS 27 |
SDSS-J150247.62+622018.9 | ||
|
ELARS 28 |
SDSS-J115218.74+585657.0 | ||
|
Tol 1214 |
Tololo 1214-277 | ||
|
Tol 1247 |
Tololo 1247-232 | ||
|
J 1156 |
SDSS-J115630.63+500822.1 |