scratch Command


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


 
Usage: scratch scr_num  int_time num_coavgs ["title"]
Category: Data Acquisition Command
Description: This command is exactly the same as run except:
  • the output file is named 's<scr_num>.fit' where scr_num is specified as a command line argument.
  • the OBSTYPE header reflects SCRATCH not RUN status
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.

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.

The output file is FITS compatible and contains complete header information (except where such information is unavailable due to a WHT subsystem (eg the TCS) being offline.
 
Arguments: scr_num  specifies a number that is used in the naming of the FITS output file. Should be within the range 1..99.

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. 

title is optional, but if specified provides additional information which is recorded in the FITS headers. The title string should be contained in double quotes if it is more than one word.
 
Examples: scratch 1 10 1 - take a 10 second exposure with no coaveraging, storing in file 's1.fit'

scratch 7 10 3 - takes three 10 second exposures in succession, then coaverages the data before storing in the output file (named 's7.fit').

scratch 4 1 1 "this is a test" - takes a single 1 second exposure with the FITS OBJECT keyword set to "this is a test". The output file is named 's4.fit'.