Department of Physics AstroLab

A new improved verison of this pipeline is now available, i.e.  photom_ad2.html .

This python script is used to derive aperture photometry from AstroLab CCD images in an automatic fashion when the (RA, Dec) positions of the target objects are known. The instructions given below outline how the script is run. The script can be found at:


You should examine the script in order to understand the general principles of the pipeline, e.g. This uses the support script

  1. Ensure the environmental variables for "convert" routines are setup, i.e. type convert
  2. Make up a directory, e.g.:
     mkdir yy_mm_dd 
     cd yy_mm_dd    
    Copy the images from the server as required, e.g. for EAST-14:
     cp /archive/east-14/year/yy_mm_dd/ad0*.fits . 

    where for example year is 2008 and yy_mm_dd is 08_01_28

  3. Fix the file needed for the automatic identification of the target.
    • For a minor planet target, run
      to produce "orbital_elements" file.
    • For a variable star target create the file "var_sky_position" containing the (RA, Dec) position in decimal degrees of the target. The position needs have an uncertainty of one arscsecond or better, i.e ~0.0003 deg.
  4. For DRACO1 images copy an appropriate dark frame from
    to "master_dark.sdf".
    (This step is not necessary for the other telescopes, including DRACO2, where the images should have been subtracted already)
  5. If necessary make a flat field image, see Flat Fielding. If the script finds a file called "master_flat.sdf" in the processing directory this is applied.
  6. Copy "/mnt/64bin/auto_astrom/automag_driver" and change as required. Ensure that the "pixscale" (pixel scale) parameter is correct for your telescope/CCD combination (e.g. DRACO scale = 1.58", West-14 = 0.90", 16-inch Far East = 1.0?", East-14 scale = 0.99") or the automatic astrometry matching is unlikely to work.
  7. Process the first frame, e.g.
     python /mnt/64bin/auto_astrom/ filename 
    (include the .fits/.st9 extension in the filename)
    This should produce a new fits file which includes an astrometry solution, e.g. d{filename}_ast.fits , plus a "amag.out" file which will include (RA, Dec) as well as (x,y) positions.
  8. Use GAIA to display d{filename}_ast.fits and select two suitable calibration stars.
    Extract their (RA, Dec) from "amag.out" and put in the file "cal_sky_positions"
    (For variable star targets this will be the same for all runs)
  9. As a test, now run the script again, e.g.
     python /mnt/64bin/auto_astrom/ filename  
    Now a measurement line should be append to the "summary.obs"
  10. Copy the python script "/mnt/64bin/auto_astrom/" and change as required.
  11. Run, e.g.
  12. Sit back and be impressed, very impressed (when it works!)

Back to the AstroLab Home Page jrl 2020-Jun-17 12:51:50 UTC