And another question from reader Korinne:
With data all observed looking for a particular spectral line over a few objects, should you use different frequency ids for the objects or can you use the same frequency id? I've been using a suggested value of a 2 MHz frequency tolerance in the manual which means they all end up with the same frequency id, but I do not know if it's right.
If you're a continuum observer (especially if you use the single-channel, 50 MHz correlator setting at the VLA), it's important to remember when reducing line data that each different set of frequencies in line data is given its own FreqID number. Some tasks work fine with datasets with multiple FreqIDs (e.g., LISTR), but other tasks (e.g., TVFLG or SPFLG) need to be told what FREQID to use or they won't find the data. You can control how the FREQIDs are assigned in FILLM.
If you have a question about AIPS that CANNOT be answered by reading the documentation, write it as a comment to one of our posts, and we will put it up on this blog for discussion!
