Processing your images

First you should create your own images and register directory. Put your images in the images sub-directory and copy the .csh and config files from the previous register directory. You must supply a dates file in your register directory (name and date of observation of the images).

Then edit process_config and choose a frame for astrometric registration (e.g. you best frame). You must also choose a degree for the astrometric regsitration, for small images 1 is ok, for larger images take 3. Run
interp.csh to get all your interpolated images (interp_* files).

Once you have your interpolated images you can start playing with image subtraction. Do exactly what we did in the previous chapter. Try different deg_spatial, sub_x, sub_y, deg_bg, until you get a satisfaying subtracted image (conv.fits). In some case, you may need to change your kernel and stamp size. If your image is very undersampled (small PSF), try to reduce the kernel and stamp size. Similarly, if your PSF is large try to increase the kernel and stamp size. If you do that change also the width of the 2 largest gaussians (in the same direction). But it is unlikely you will have to go in these complication. If you are unsure ask me.

C. Alard: alard@iap.fr

When you have choosen your parameters, you can follow the procedure which was illustrated in the tutorial. Just before you make the light curve (phot.csh), don't forget to have a look at process_config. Some comments about this file were already given in the tutorial.