Appendix A.    Data Reduction with IRCAM_CLRED

 

These notes are taken from UKIRT's IRCAM3 manual by Colin Aspin, and modified for WHIRCAM. A UNIX version of IRCAM_CLRED has also been recently written, called IRCAMDR.

Either log onto any of the Vaxstation terminals (LPVS3 or LPVS5) as user OBSERVER (get current password from SA or TO), or open another DECterm window on the WHIRCAM terminal, then type (where YYYYMMDD is the current year, month and date, eg 19960229):

	ircam_setup
	set def DISK$IRCAM:[WHIRCAM.DATA.IRCAM_DATA.YYYYMMDD.RODIR]
	ircam_clred

You will be asked to supply the same ID as you entered under IRCAM_DEV, a workstation number (always choose 18), the data format (`NEW' for WHIRCAM data), the UT date relevant for the frames taken (eg 960229), a filename suffix (choose `none') and the plate scale (0.24 ''/pix for WHIRCAM direct).

The IRCAM Command Line REDuction system will now run up and present you with the IRCAM logo (on the graphics window) and the prompt:

Ircam-Clred >

You can, if you like, reduce the size of the DECterm windows to see the whole of the GKS graphics window by clicking on `Options' and selecting `Window' and clicking on `Condensed Font' then `Apply' and finally `OK'.

Once in IRCAM_CLRED, the system is setup to access the reduced observation files (prefixed by RO) in the current directory by their observation number alone.

• To display an RO image (eg observation 42) type:

  NS 42 <CR>

• To display the difference between two images (say, an OBJECT and a SKY or two OBJECTs at different spatial positions) type:

  DISP 42 41 <CR>

  to subtract 41 from 42 and plot the difference.
• To define a zeropoint use the command:

  STDPHO 41 42 <CR>

  where observations 41 and 42 are the first two images of a faint standard (FS) 5-point mosaic (see § 6). The difference between the two images will be plotted and you will be asked to select the standard star with the cursor. The system will calculate a zeropoint and load it into the system.
• To reduce STARE and ND_STARE mosaics type:

  STRED <CR>

  Below is an example of the input required by STRED.

  Ircam-Clred > stred
  Current IRCAM file prefix =  RO960229_
  Current IRCAM file suffix =  NONE
  Enter a PREFIX for the output image(s)
  Prefix    |IMAGE_| ? field22_
  Enter start observation number ?
  Start           |1| ? 21
  Enter number of images to be reduced ?
  Number of Images |1| ? 5
  Enter the DARK image number :
  Dark number    |1| ? 2
      Observation specified as DARK is truly a DARK!
      CONGRATULATIONS, you did good!!!
  Do you want to MEDIAN FILTER the objects for a flat or
  use a SEPARATE pre-prepared (normalized) SKY image ?
  Median or Separate Sky (M,S) |M| ?
  Do you want the images airmass corrected ?
  Airmass Correction (Yes or No) |N| : y
  Do you want the images auto-mosaiced ?
  Mosaicing (Yes or No) |Y| : y
  Getting RA,DEC offsets from input images...
    Image  RO960229_21
    Image  RO960229_22
    Image  RO960229_23
    Image  RO960229_24
    Image  RO960229_25
  RA,DEC (modified) offsets in image sequence are :
       0.000     0.000
       0.656    -5.297
       6.178    -5.124
       6.268     0.379
       5.633     5.411
  Use these offsets or use user-defined telescope  offset (ASCII) file ?
  File Offsets or User-defined (F,U) |F| ?
  Give name for FINAL mosaiced image :
  Final Image |X| ? field22_final

  STRED then reduces the specified images and, if requested, puts together the final mosaic. Output images will be, as in the e.g. above,

  FIELD22_21DFGA
  FIELD22_22DFGA
  FIELD22_23DFGA
  FIELD22_24DFGA
  FIELD22_25DFGA
  FIELD22_FINAL

Other useful IRCAM_CLRED commands include:

• CSTATS gives statistics (max,min,mean,median,1-sigma std) on cursor defined box on image.
• LIMAG gives 1-,5-,10-,100- sigma limiting magnitudes of images/mosaics once zeropoint has been defined.
• PHO to get photometry of sources - 4'' aperture is good for faint standards, 2'' is good for faint sources (e.g. asteroids, QSOs etc).
• EXIT to exit.