glance Command


This page is part of the ING manual WHT-INGRID-2: INGRID IMPB Software Operations Manual


 
Usage: glance int_time num_coavgs
Category: Data Acquisition Command
Description: This command is exactly the same as a run except that:
  • the output file is named 'glance.fit'.
  • the amount of header information in the output FITS file is greatly reduced (it only contains the mandatory FITS keywords required to describe the image data).
Because of the above:
  • the title argument is not required (cf dark / flat / run commands).
  • the command executes more quickly.
The basic detector exposure sequence is a Multiple Non-Destructive Read (MNDR). This consists of a detector reset, Nr pre-integration reads, an integration period, then Nr post-integration reads. The pre-integration data and post-integration data are each summed and averaged two produce two distinct data sets for storing in the output file.

The number of reads in the MNDR cycle may be modified using the numreads commands. 

If the coaverage option is specified then the MNDR sequence may be repeated and the resulting pre and post-integration data-sets averaged before saving in the final output file.
 
Arguments: int_time is the MNDR integration time specified in seconds to the nearest millisecond. The minimum integration time is determined by the speed with which the SDSU Controller can scan the Hawaii detector array (typically about 1.2 seconds).

num_coavgs specifies the number of coaverages in the observation sequence. num_coavgs should be a positive integer in the range 1 to 100. 
 
Examples: glance 10 1 - take a 10 second exposure with no coaveraging.

glance 10 3 - takes three 10 second exposures in succession, then coaverages the data before storing in the output file.