INT Duty Engineer Checks
The Wide Field Camera (WFC) Sensitivity Check with UltraDAS

Reason

The purpose of this document is to provide a simple check on the sensitivity of the four CCDs that comprise the WFC.  The check involves taking a flatfield and determining the number of counts that appear in each CCD image.

Procedure

1. Switch on the main dome lights.
2. Select an appropriate filter from table 1.
3. Position the telescope as indicated in table1.
4. Take a flat exposure using the appropriate integration time.
5. Display the image in IRAF using the wfc_disp command.  Prior to doing this it may be wise to use the IRAF "unlearn display" command to clear any custom display parameters.
6. From the associated output, check that the Z1 (or Z2) values do not differ significantly.  They should be within about 20% of each other.  If a factor of 2 or greater exists, this represents a problem which should be reported to the detector specialists.

Table 1

Document History

Rev 0.1 Draft issue: Nov 27^th 2006  Don Carlos Abrams
 

This file:  http://www.ing.iac.es/~eng/ops/int/wfc_sensitivity.html