IRAF tips
If you have never set up IRAF
on your linux account, do the following:
- in your home directory, set up an iraf subdirectory: mkdir iraf
- cd into that directory, and type mkiraf. when it asks you what kind of terminal
you will be using, say xgterm.
- it will create a file called login.cl.
Edit this file in the following ways:
- Change the line that reads #set
stdimage = imt800 to read set stdimage = imt8192 (i.e., uncomment and
change value)
- Change the line that reads #set
imtype="imh" to read set imtype = "fits" (i.e., uncomment and
change value)
To start iraf:
- start an xgterm window by typing xgterm -sb &
- in the xgterm window, cd to your iraf directory and type ecl which will start IRAF
- from now on, all IRAF commands should be executed from that
xgterm window
- in the xgterm window, cd to the directory that holds your
data.
- start ds9 by typing !ds9
&
- you should be good to go now
Miscellaneous tips, as I think of them:
- when using imexamine, remember that the ds9 window needs to be
selected/active. if one of the other windows is active,
imexamine won't pay attention to your keystrokes even if your
cursor is in the ds9 window. (I
highly recommend setting up your window manager so that you
activate windows by simply moving the cursor into them, rather
than the awful default of having to click a window to make it
active.)
- you will frequently need to load "packages" to run certain
commands. For example, the daofind and qphot commands are part
of the noao.digiphot.apphot package. To load this package you
would type (in IRAF) noao,
then digiphot, then apphot. now you can run
daofind and qphot. so if a command doesn't run, make sure you've
loaded the package that contains it (which is usually noted at
the top of the IRAF help page for that command).
- to edit the parameters a command uses, type epar <command> which
will let you edit the parameters. do a :wq to save the commands and
get back to IRAF.
- sometimes commands will have both parameters and
subparameters. For example, if you epar apphot, you will see
parameters called datapar
and findpar. these are
actually subparameters. if you go to those parameters and type :e you will get into a new
subparameter set. edit those subparameters, then do a :wq to get back to the main
parameters, and another :wq
to get back to IRAF.
- If you have a file where the first two lines are x,y image
coordinates, you can overplot those positions in ds9 by going to
Region -> Load Region,
clicking All, and then
choosing the file. When the load window pops up, tell it that
the file format is xy
and that the coordinate system is image. (if you had a file of ra & dec, you
could tell it the coordinate system is wcs....)
- In any command that wants to know certain keywords from the
image header, exposure time is EXPTIME, airmass is AIRMASS, and
obstime is DATE-OBS. If you set these this way, you'll be
happier. You can always see what's in the image header by
loading the image into ds9 (don't
display it through IRAF) and choosing File->Display Fits Header.