** This utility may be used to identify and rectify saturated stars located within IRAC BCD images.** It uses a set of tools that were developed with Solaris unix (there is also a MacOSX version). Below are the install directions and some brief tips for using the tool. Contact T. Jarrett for the file installation.
/home/jarrett/wirc/cl/iracworks.csh fits_file_name Usage example:
/home/jarrett/wirc/cl/iracworks.csh IRAC.4.0006581504.0003.0000.4.bcd_fp
This utility allows the user to:
The crater finder utility requires the user to supply a table of 2MASS stars appropriate to the image field. This table may be created using IRSA's GATOR database.
This utility uses the algorithm discussed here: Bright Star Rectification. For the graphical interface, it uses "skyview" linked to a fortran binary, as well as the plotting utilities "wip" and "pgplot". For FITS manipulation, it requires the FITSIO library to compile. If this fails, contact T. Jarrett or Lee Rottler.
Files needed to install:
After success compile and linking, the first step is to edit the "iracworks.par" and set the parameters to your liking. Use the default values to start with (do not change anything until you know what you are doing). You will need to set the correct paths for the skyview, xv and wip binaries. And finally, you will need to set the correct paths to the PSF images (included in the installation tarball). Place the PSF files in an appropriate location and set the paths in the "par" file.
Now you are ready to run the tool. Get an IRAC BCD image that has a bright
star in it. Run the tool (see above). The first thing you see is a zoomed
view of your BCD. Change the stretch if need be (see option "r").
To choose a star, select option "p", and click on your star. Try to be as close
to the center as possible (with saturated, mangle images, this can be tricky).
You will see a zoomed version of your star. If need be, recenter on the star
(use option "p" once again). You may mask stars at this point, but you need
only worry about stars located within the green box (the effective area of
operations). Now you are ready to process -- select "q" or just hit
AFter a few seconds, the result will appear. You will get a wip gif file
displayed to screen. In the upper left corner is the BCD, with the selected star
circled. A resampled & zoomed version is shown in the upper right. The middle
panel shows the radial profile of the star, normalized by the model. The signature
of saturation is the central core turning 'down', meaning that the starlight is too small
compared to the PSF. The model is also shown in the middle panel. The bottom panels
show the starlight-to-model residual image and the rectified image.
At this juncture you may tweak the center location of the saturated star based
on the residual image. With practice you can tell how much tweak of the X and Y positions
are needed to properly center-up the star. Select option "t" to tweak the position --
enter the delta-X and delta-Y tweaks (typically 1 or 2 pixels are all you need).
After you are happy with the centering, you can change the 'replacement' radius
at which the BCD image is replaced with the model. Note that for channels 3/4,
I suggest that you use a large replacement radius, sufficient to remove the
god-aweful bandwidth effects (they look like ghosts on the right side of the nucleus).
Again, with practice and fiddling of these parameters, you can get the desired effect
in short order.
When complete, just hit