Working with WIRO data

Here are some of the things you need to do before using the ccdred programs to bias subtract and flatfield the WIRO data.

Below I've included a short description of each one of these steps along with an example processing session where appropriate.

Edit login.cl

Use atom to edit your login.cl so that ds9 will display the entire 4096 by 4096 image. Do this by finding the set stimage command in the file, and change it to read:

set stdimage = imt4096

Use setinstrument to setup ccdred

First use epar to edit the setinstrument site parameter to wiro. Then run setinstrument and choose DoublePrime as the instrument. When you are finished the setinstrument parameters should be set as shown below.

ccdred> lpar setinst
   instrument = "DoublePrime"   Instrument ID (type ? for a list)
        query = "DoublePrime"   Instrument ID (type q to quit)
        (site = "wiro")         Site ID
   (directory = "ccddb$")       Instrument directory
      (review = yes)            Review instrument parameters?
        (mode = "ql")

Run WDPzero.cl

Download the latest WDPzero.cl script from the WIRO website. Put the script in the directory with the images you wish to process. Make a list of the image file names. You can do this with the UNIX ls command.

$ ls -1 *.fit > filelist

Now start iraf, go to the directory with your files, and follow instruction on the website to define the task and run WDPzero.

ecl> task WDPzero=WDPzero.cl
ecl> WDPzero("filelist")
overscan zero subtraction script for WIRO Double Prime imager
Input file names must end in .fit and _z will be appended
a001_z.fits
a002_z.fits
a003_z.fits
.
.
.

The WDPzero("filelist") command will take some time to execute. The processed files will have the same root name as the originals, but with an _z. Note that on our systems the processed files will have the extension .fits rather than .fit. These are the files you will use for the rest of the processing.

Set the image type

The WIRO data images don't have the imagetyp header keyword set so we'll have edit the all the FITS files to add that keywork in order to process the images with ccdred.

The first step is to make three lists. One list with only the bias image file names, one with the flat image file names and one with the object file names. I think the easiest way to do this is just make three copies of the filelist called biaslist, flatlist, and objectlist. After you've created these lists just edit them with atom to remove the files that aren't of the desired type. You should also display the images and eliminate any saturated or bad images from your bias and flat lists.

Now we use ccdhedit to add the appropriate imagetyp header keyword to each image.

ccdred> ccdhedit @biaslist imagetyp zero
ccdred> ccdhedit @flatlist imagetyp flat
ccdred> ccdhedit @objectlist imagetyp object

Correct the filter keyword

  1. Use IRAF's hselect command to generate a file containing files names with filter information.
ecl> hselect @filelist $I,filter yes > filefilterlist
  1. Use python program MakeFilterList.py to make a list of files for each of the desired filters. The program will create a file with the name filtefilterlist_x where x is the selected filter. The file contains the names of all the files with that filter.
(iraf27)$ python MakeFilterList.py
Using list: filefilterlist
Enter the desired filter ('u', 'g', 'r', 'i' or 'z'): u
a001.fit u' u
a002.fit u' u
a003.fit u' u
a004.fit u' u
.
.
.
  1. Use ccdhedit to edit all of the files for each filter.
ccdred> ccdhedit @filefilterlist_u filter u

You should now be ready to use the ccdred package programs to bias subtract and flat field all of the WIRO images.