Mission Overview
CANDELS Lyman Alpha Emission at Reionization Survey (CLEAR)
Primary Investigator: Casey Papovich
HLSP Authors: Raymond Simons, Casey Papovich, and Ivelina Momcheva
Released: 2023-03-15
Updated: 2023-03-15
Primary Reference(s): Simons, Papovich, Momcheva et al., 2023
DOI: 10.17909/9cjs-wy94
Citations: See ADS Metrics
Source Data:
Slideshow
Footprints of the CLEAR fields in GOODS-North (left) and GOODS-South (right). Main panels: CLEAR G102 observations (blue, solid line) overlaid on the footprint of the CANDELS WFC3 imaging (gray). Also shown are the overlapping pointings of G102 (blue, dashed line) and G141 (red, solid line) grism observations from ancillary programs that are included in the data reduction and analysis. Top and bottom side panels: zoomed-in view of each of the 12 CLEAR fields.
The G102 and G141 spectra of a single galaxy (ID: 38616; z = 1.31) in the GS5 CLEAR field. The top row shows the 2D (spatial x spatial + spectral) spectra from the WFC3/G102 (left) and WFC3/G141 (right) grisms. The second row shows the respective continuum models. The third row shows the residual of the two (spectrum - continuum). Emission line flux (which is not included in the continuum model) appears as a bright feature in the 2D residual spectrum. Prominent emission line/line complexes are indicated. The bottom panel shows the 1D extracted spectrum (G102 in blue and G141 in red-orange) along with the full continuum + emission line fit (red line). The overlapping photometry is shown with the black squares. The faint grey points show the spectral flux density measured for each individual exposure.
Overview
The CANDELS Lyman-⍺ Emission at Reionization (CLEAR) survey is a HST Cycle 23 program that obtained 12-orbit depth observations with the HST/WFC3 using the G102 grism in the IR camera in 12 fields split between the GOODS-N and GOODS-S fields from the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS). Combined with existing spectroscopic data (G102 and G141) from other programs, the dataset released here includes 1D and 2D spectra over (partially- or fully-covered) 0.8-1.7 um for 6048 galaxies in GOODS-South and GOODS-North to m_H = 25. In addition, this release includes updated photometric catalogs from the 3D-HST survey, and spectroscopic catalogs that include emission line fluxes and redshifts derived from the combination of the photometry and grism spectroscopy.
The primary goal of CLEAR was to characterize the evolution of the Lyman-⍺ equivalent width distribution at 6 < z < 8 and to interpret this in the context of reionization. The CLEAR dataset also allows for studies of the stellar populations, star-formation, ionization, and chemical enrichment of galaxies in the distant universe (from redshifts z~0.5 to 3).
Data Products
Data Files
Data files are organized according to the following file structure:
data/<filetype>/
where:
- <filetype> is the file type, one of "full", "beams", "stack" or "1d". See table below for descriptions.
Data files are named according to the following convention:
hlsp_clear_hst_wfc3_<target>-<source>_g102-g141_v4_<filetype>.fits
where:
- <target> is the name of the target, one of "ersprime", "gn1", "gn2", "gn3", "gn4", "gn5", "gn7", "gs1", "gs2", "gs3", "gs4", or "gs5".
- <source> is a five-digit extension corresponding to the source ID number.
- <type> is the file type, one of "full", "beams", "stack" or "1d". See table below for descriptions.
Data file types:
|
_full.fits |
The results of the continuum + emission line fits. |
| _beams.fits |
The 2D G102 and G141 spectra and the F105W and F140W direct images. |
| _stack.fits |
The stacked 2D G102 and G141 spectra of the source. |
| _1d.fits |
The optimally-extracted 1D spectrum of the source. |
Photometric Catalogs
The photometric catalog files, updated from the 3D-HST team to include F105W from CLEAR, are organized according to the following file structure:
catalogs/<field>/photometric_catalog/
and the files are named according to the following convention:
hlsp_clear_hst_wfc3-acs_<field>-3dhst_multi_v4.6_<cat_type>.txt
where:
- <field> is the target field, one of "gds" or "gdn".
- <cat_type> is the type of catalog, one of "cat" (zeropoint-corrected) or "nzpcat" (not zeropoint-corrected).
Spectroscopic Catalogs
The spectroscopic catalog files are organized according to the following file structure:
catalogs/<field>/spectroscopic_catalog/
and the files are named according to the following convention:
hlsp_clear_hst_wfc3_<field>_multi_v4.1_clear.fits
where:
- <field> is the target field, one of "gds" (GOODS-S) or "gdn" (GOODS-N).
EAZY Analysis Files
The files associated with EAZY analysis are organized according to the following file structure:
catalogs/<field>/eazy/
and the files are named according to the following convention:
hlsp_clear_hst_wfc3-acs_<field>-3dhst_multi_v4.6_<ext>
where:
- <field> is the target field, one of "gds" (GOODS-S) or "gdn" (GOODS-N),
- <ext> is the file type and extention, see table below for possible values.
Data file types:
| _zphot.translate
|
Eazy-py filter translate file. |
| _zphot.param |
Eazy-py parameter file. |
| _zout.fits |
Eazy-py derived galaxy properties (stellar masses, rest-frame colors, photometric redshifts) |
Data Access
Data Files
cURL scripts for downloading CLEAR data products for all targets can be accessed from the table below (see previous section for data product descriptions):
| cURL Script | Estimated Download Size |
|---|---|
| Full |
118 GB |
| Beams |
172 GB |
| Stack |
6.1 GB |
| 1D |
0.3 GB |
Catalog Files
| Field | Photometric Catalogs | Spectroscopic Catalogs | EAZY Files |
|---|---|---|---|
| GOODS-N | With zeropoint correction | Without zeropoint correction | Catalog | |
| GOODS-S | With zeropoint correction | Without zeropoint correction | Catalog |