VIRCAM Pipeline  1.3.3
vircam_detector_noise
Recipes

Work out the read noise and gain of a detector. More...

Work out the read noise and gain of a detector.

Name:
vircam_detector_noise
Purpose:
Work out the read noise and gain of a detector
Description:
The input dome flat exposures and dark exposures are used to determine the read noise and gain of a detector. The method uses two exposures of each. The dome flats and the dark frames should be done with the same exposure times. A simple statistical method is used to work out the desired values. See section 2.4 of the VIRCAM Data Reduction Library Design document for further information.
Language:
C
Parameters:
  • thr (float): The rejection threshold in numbers of sigmas.
  • ext (int): The image extension of the input files to be done on this run. If all of the extensions are to be processed, then this should be set to zero.
Input File Types:
The following list gives the file types that can appear in the SOF file. The word in bold is the DO category value.
  • DARK_GAIN (required): A list of two raw dark images. If any more are found in the list, they will be ignored.
  • FLAT_LAMP_GAIN (required): A list of two raw dome flat images. If any more are found in the list, they will be ignored.
  • MASTER_BPM or MASTER_CONF (optional): A master bad pixel mask. If this is omitted then all pixels are assumed to be good.
Output Products:
The following list gives the output data products that are generated by this recipe.
  • An output readnoise/gain file (READGAIN_TABLE). The exact content of the columns is described in chapter 5 of the DRLD.
Output QC Parameters:
  • READNOISE The readout noise of the detector in electrons
  • CONAD The gain of the detector in electrons per ADU.
Notes
None.
Fatal Error Conditions:
  • NULL input frameset
  • Input frameset headers incorrect meaning that RAW and CALIB frame can't be distinguished
  • Insufficient dark or flat exposures
  • Unable to save data products
Non-Fatal Error Conditions:
  • Missing bad pixel or confidence map. All pixels considered to be good during the stats phase.
Conditions Leading To Dummy Products:
  • Image extensions wouldn't load.
  • The detector for the current image extension is flagged dead
  • Unphysical statistical result
Author:
Jim Lewis, CASU
Code Reference:
vircam_detector_noise.c