Monday, April 2, 2012

Getting tsField files from SDSS

I'm always looking for this or that little piece of code I really wrote sometime ago but can't remember where I put it. Then I end up rewriting it because it is faster than grepping entire work directory and sorting through the offal. I wrote about batch downloading of SDSS images, now it seems I need a specific pipeline parameter from all 900 tsField files. Here's a oneliner (from a multi-line blob of code I'm now keeping at GitHub).

After downloading (or just reading the parameter from header and moving happily along, I'm currently figuring that out)-- no downloading. I'm reading the value from header via http, as pyfits are capable of that.


  1. Hi,

    Could you plz let me know how to read or download the tsField file from SDSS?
    I need aa, kk and airmass valuse in all respective bands.

  2. Hi there,
    they are ordinary fits files. The snippet I used looks like:

    tsFile =''+run+'/'+rerun+'/calibChunks/'+camcol+'/tsField-'+runstr+'-'+camcol+'-'+rerun+'-'+field_str+'.fit', mode='readonly')

    img = tsFile[1].data
    #indexing -- field numbering in documentation starts with 0, hence #27 instead of #28 field, etc
    zpt_r = list(img.field(27))[0][filterNumber]
    ext_coeff = list(img.field(33))[0][filterNumber]
    airmass = list(img.field(22))[0][filterNumber]
    params = [zpt_r, ext_coeff, airmass]

    1. Thank you very much for your reply..

      I am new in this work so could you plz explain me where I should run this coding?
      I do not have pyfits in my laptop.
      I am trying through CasJobs - login - query - MyDB etc