etc-EXPID

Summary:

JSON file containing details of the ETC analysis for one DESI spectrograph exposure.

Naming Convention:

etc-EXPID.json, where EXPID is the zero-padded 8-digit exposure ID.

Regex:

etc-[0-9]{8}\.json

File Type:

JSON, 100 kB

Contents

Each file contains a dictionary with the following top-level keys:

Key	Description
desietc	Version number of the desietc package used.
expinfo	Information about this spectrograph exposure including a summary of the results of analyzing the initial GFA acquisition images.
fassign	Information about the fiber assignment for the tile to observe used by the ETC.
acquisition	Details from the analysis of the initial in-focus GFA acquisition images.
-guide_stars	Details of the guide stars used from each in-focus GFA.
header	List of the ETC summary keywords that also appear in the main spectrograph FITS file.
shutter	Tracking of successive cosmic-split exposures.
thru	Details of the per-GFA exposure analysis of fiber acceptance fraction and atmospheric transmission contributing to the signal throughput.
sky	Details of the per-SKYCAM exposure analysis of relative sky background levels.
accum	Details of the ETC model of accumulated of signal to noise after each GFA and SKYCAM exposure.