[ ESO ]
HAWKI Quality Control:
Twilight Flat

CAL | HC | refs | QC
Trending & QC1
   TW Flat
Data Packages
Data Management
QC links:
hawki_twflat :: HAWK-I_QC_FLUX_RANGE
Daily Health Checks:    
flux range
QC1 hawki_dark database (advanced users): browse | plot
   Click on CURRENT to see the last trending (Health Check).
   Click on HISTORY to see the historical evolution of the trending.

top Introduction

This tutorial provides information for the the TW Flats Health Check trending.
The TW Flats trending is based on the measurement of QC1 parameters from the twilight flat field calibration data. Following the calibration plan, the twilight flat fields are taken during evening (usually) and morning (rarely) twilights with clear skies as required for the calibration of SCIENCE data.
HAWK-I instrument does not have an internal lamp. In the infrared, twilight flats are taken in a manner to sample a large flux range by integrating on the twilight sky as the sun sets or rises. Twilight flats are therefore, one of the most time critical calibrations, since of the narrow time window. This is also the reason why more operational related quality parameters like the covered flux range are monitored for twilight flat calibrations.
The standard deviations of the pixel values of each detector in the MASTER FLAT image are monitored in J, H, Ks & Y filters.


QC1 parameters

  • flux range within raw frame stack (QC1 database table hawki_twflat, column qc_flat_medstdev, product keyword QC.FLAT.MEDSTDEV)
    Description: The standard deviation of the raw frame fluxes as a rough measure of the covered flux range.