Emission line maps

Filename structure

Each filename starts with a Grizli root identifier followed by the source ID as so:


where X gives the SpARCS ID and A gives the source ID.


For each GCLASS cluster, a .zip file is provided below which contains a .fits file and a .png file for each source.

FITS file

The .fits file contains 80 x 80 pixel (0.1 arcsecond pixel scale) thumbnails of the blotted* direct images, associated weight, segmentation and PSF maps for the source. They also contain 80 x 80 pixel (0.1 arcsecond pixel scale) thumbnails of the drizzled emission line maps, associated weight, continuum and contamination maps. The number of fits extensions in this file will depend upon the number of emission lines detected. The different types of fits extensions in this file (in order) are as follows:

  • ZFIT_STACK - table fits extension containing information regarding the p(z) distributions from the Grizli fits for the source. A .png file showing these fits is in the first panel of the .pngs found here. This fits extension also contains information regarding the SED model fit to the grism spectrum.

  • COVAR - the fits header of this extension contains the fluxes, errors on the fluxes and equivalent width measurements for all emission lines.

  • TEMPL - table fits extension containing template coefficient values of each emission line for model fits.

  • SEG - direct image segmentation map thumbnail for source.

  • DSCI - blotted* HST WFC3 F140W direct image thumbnail.

  • DWHT - blotted* HST WFC3 F140W direct image inverse variance thumbnail.

  • LINE - emission line map thumbnail. Contamination and continuum has been removed.

  • CONTINUUM - stellar continuum (at the position of the emission line map) thumbnail.

  • CONTAM - contamination (at the position of the emission line map) thumbnail

  • LINEWHT - emission line map inverse variance thumbnail.

  • DPSF - blotted* HST WFC3 F140W empirical PSF thumbnail. See section 4.2 of Mowla+18 for more details.

Further details on these data products can be found in the Grizli documentation here.

*If you are doing a study where you need to compare direct images to emission line maps, you CANNOT use the direct image thumbnails in this .fits file (see here for why). Use the direct images provided here instead.

PNG file

The .png file shows a 2D, zoomed-in rendering of the DSCI HST WFC3 F140W direct image thumbnail with the grism redshift stated in the title, after which 2D, zoomed-in renderings of all the emission line maps detected are shown. The line and its observed wavelength in the grism spectrum are stated in the titles of these panels.