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

"jXXXXYYmZZZZ_AAAA" or "jXXXXYYpZZZZ_AAAA"

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 beams.fits, stack.fits and stack.png file for each source.

beams.fits file

Contains each independent G141 grism + F140W imaging observation and their associated calibration images. For each independent observation, the fits extensions provide (in order they appear in the fits file):

• REF - reference F140W direct image of the source.

• SEG - F140W segmentation map for the source.

• SCI - G141 grism spectrum of source.

• ERR - pixel-by-pixel error for the G141 grism spectrum.

• DQ - data quality flag (see here for explanation)

• CONTAM - grism spectrum contamination map.

There tend to be several independent observations per position angle of the G141 grism. The contamination and continuum have not been removed from the SCI extensions in this file.

stack.fits file

Contains the stacked G141 grism spectrum per source for (in order they appear in the fits file):

1. Each position angle of the G141 grism.

2. Combined position angles.

For each of the above, the fits files provides (in order they appear in the fits file):

• SCI - stacked G141 grism spectrum.

• WHT - Inverse variance map.

• CONTAM - Contamination map.

• MODEL - Continuum model for the source and contaminating sources. Emission lines not included.

• KERNEL - WFC3 PSF model.

Since the GCLASS observations were conducted at a single position angle, the two stacked G141 spectra in this file are identical.

stack.png file

Shows the two stacks in the stack.fits files in the order they appear in the stack.fits file.