Mission Overview

Faint Infrared Grism Survey (FIGS)

Primary Investigator: Sangeeta Malhotra

HLSP Authors: Norbert Pirzkal, Nimish Hathi

Released: 2020-xx-yy

Updated: 2020-xx-yy

Primary Reference(s): Pirzkal et al. 2017

DOI: 10.17909/T9010Z

Citations: See ADS Statistics

Read Me

Source Data:

FIGS GOODS-N Pointings

GOODS-N Field showing two FIGS (WFC3 G102 grism) pointings on the GOODS tiles. For reference, PEARS (ACS G800L grism) pointings are also shown.

FIGS GOODS-S Pointings

GOODS-S Field showing two FIGS (WFC3 G102 grism) pointings on the GOODS tiles. For reference, PEARS (ACS G800L grism) and GRAPES/HUDF (ACS G800L grism)pointings are also shown.


FIGS is the Faint Infrared Grism Survey HST program. FIGS was conducted in the GOODS North (GOODS-N) and GOODS South (GOODS-S) fields using the Wide Field Camera 3 (WFC3) G102 grism in Cycle 22. Observations were made during the period 2014 October 17 to 2015 December 15 through 160 orbits that were allocated for the program. Slitless spectra over four FIGS fields (two in GOODS-S and two in GOODS-N) were obtained with the WFC3 and the G102 grism over the 136x123 arcsec detector area. Five position angles (PAs) were obtained for each FIGS field.  Short F105W images were also obtained to align to the GOODS astrometry and to provide the zero point of the slitless spectra. The G102 grism provides slitless spectra with a dispersion of about 25 Angstroms per pixel, but the achieved spectral resolution depends on the size of the dispersing object. For a point source, the measured resolution is about 200 Angstroms, varying with wavelength. The grism first order covers 8000-11500 Angstroms with peak sensitivity around 11000 Angstroms. In addition to the WFC3 IR slitless spectroscopy and imaging, coordinated the Advanced Camera for Surveys (ACS) parallels were obtained in the FIGS program in the G800L grism filter. The ACS G800L data are not included in this release.

The project has made the basic FIGS Catalogs (used for extraction) available. A set of web pages with browsable spectra is also available (links given in the 'Data Access' section below). Shown for each object are: the catalogue number, the x,y position and the RA and Dec (J2000), the F105W magnitude, direct image cutouts (image, segmentation map, contamination), 2D grism cutouts (different PAs, contaminations, residuals), 1D plot of flux vs. wavelength for the available PAs, and 1D plot of flux vs. wavelength all PAs combined. In some cases not all the five position angles have grism data if one or more spectra fall outside the detector. The pages are sorted in order of increasing F105W magnitude.

Data Products

The files from each pointing and field are stored in subdirectories called "gn1/", "gn2/", "gs1/", and "gs2/" for GOODS-N and GOODS-S fields, respectively.  Inside each subdirectory are the catalog files, preview plots (in a "plots/" subdirectory), and the 1-D spectra (in a "data/" subdirectory).  At the top-most level are tar files that group the individual spectra and preview plots for a given pointing together.

The file names for the source catalogs have the following convention:



  • <pointing> is one of "gn1", "gn2", "gs1", or "gs2"

The file names for the individual, position-angle-combined spectra and preview plots have the following convention:



  • <pointing> = one of "gn1", "gn2", "gs1", or "gs2"
  • <objid> = Source Extractor object ID
  • <exten> = one of "comb.fits" or "plots.pdf" for the PA-combined spectra and preview plots, respectively

The file names for the position-angle-specific 1-D spectra have the following convention:



  • <pointing> = one of "gn1", "gn2", "gs1", or "gs2"
  • <objid> = Source Extractor object ID
  • <-|+> = positive or negative sign depending on the value of the position angle
  • <exten> = position angle, in degrees

Data file types:

_spectra.tar Bundle of all spectra and preview plots for that pointing+field.
_cat.txt Source Extractor catalog of detected sources for this pointing+field.
_readme.txt README file for this pointing+field containing some notes.
_comb.fits Position-angle-combined 1-D spectrum.
_pa????.fits Position-angle-specific 1-D spectrum.
_plots.pdf Preview plots.

Data Access

NOTE: The tar bundles in the 'File Bundle' column are ~1-4 GB in size.

Field+Pointing File Bundle Source Catalog README Spectral Browser Pages
GOODS-North 01 (gn1) GN1-ALL GN1-CAT GN1-README GN1 Preview Webpages
GOODS-North 02 (gn2) GN2-ALL GN2-CAT GN2-README GN2 Preview Webpages
GOODS-South 01 (gs1) GS1-ALL GS1-CAT GS1-README GS1 Preview Webpages
GOODS-South -2 (gs2) GS2-ALL GS2-CAT GS2-README GS2 Preview Webpages



Please remember to cite the appropriate paper(s) below and the DOI if you use these data in a published work. 

Note: These HLSP data products are licensed for use under CC BY 4.0.

Additional References