% cd <your_directory_with_observing_scripts>
and issuing the command
in that directory. The checker command has some optional switches, see Table 1.1 or type ``checker help''. It modifies your UNIX shell environment (currently only the C shell, (t)csh, is supported) and temporarely changes your prompt until you exit from this environment. It will probably create a file hatcommon (this is the infamous COMMON block), and you will eventually also see files like hatcommon.lst and hatcommon.azel, in which your LST and pointing position will be kept. The observing command
prints out the local checker (LST) time, but in checker mode it can also be used to modify the LST which is probably useful before you start testing your script.
Note: Be sure to reset your LST clock each time you run the script. Most scripts critically depend on this.
For example, setting the LST to 14:30 can be done in two ways: in decimal hour notation:
% lstsymbol lst=14.5
(decimal point required!) as well as in the hhmm notation (only digits allowed, leading zeros not required so 10 is equivalent to 0010):
% lstsymbol lst=1430
Although various observe programs (e.g. int, mint, cross) advance the LST clock, you can also manually increment it. For example,
% lstsymbol inc=30
would advance the clock by 30 minutes. Again you can enter increments in either hhmm or decimal days notation.
You may also want to set the epoch of the observation, particularly if you use planets which tend to move along the sky. By default the epoch will be set to the current day, you can change that:
% epoch 97oct03 % epoch 97oct03.25 % epoch 97oct03:6:30
You are now ready to test an observing script. You need to run it through the project command, in exactly the same way as the master script would use it during the actual observations.
% project name=test.csh start=700 stop=1730
and view the results on the screen. If you run into C-shell syntax errors, it may help to run project a higher level debug mode
% project name=test.csh start=700 stop=1730 debug=1
where the default level is 0 (no debug output). debug=1 is equivalent of running the script in verbose (csh -v) mode, whereas debug=2 runs your script in verbose plus echo (csh -vx) mode. In Section 1.8.3 we list some of most common C-shell mistakes. If neither of these help, you probably need some kind of a guru.
Older versions of checker (before fall 1997, or Version 2.x) did not use the NAIF ephemeris server program to lookup source positions. This severely began to slow down checker, as the ephemeris tables have became large. Although checker can still be installed in no-naif mode, the default is that checker now also uses the NAIF server, and will be started automatically (and killed) as you startup checker (and exit).
Although checker is now running a lot faster, a new feature will improve checker even more, particularly for scripts that use MINT's grid= keyword to mosaic observations:
% setenv HATCHKSRC 0
which disables more extensive checksource source/catalog syntax checking. You should only disable this when you are certain these are correct.
If you all done with checking, you can remove the checker environment by using the aliased command exit:
after which the real exit command becomes available again to exit the current shell. Note: checker should not be run from the obs account, as it may affect control over the real telescopes.