Here follows a description of some of the AIPS calibration adverbs. More details about adverbs can be found in the AIPS HELP files.
Sources can be selected in a variety of ways by referring to them by name, by frequency, and by coded strings and numbers. All of these methods can be useful, and you will probably evolve your own method which uses some subset of them.
The freqids and their associated frequencies can be seen in the output from LISTR discussed in § 5. freqid is useful because each collection of frequencies must be calibrated separately, so keeping all other source selection parameters the same, but changing freqid allows simple change of frequency. This is handy when your observation has been set up with continual cycling through the same groups of frequencies (e.g., to obtain separated frequencies for multi-frequency synthesis).
freqid values are stored in the FQ table, and must be specified one at a time; there is no way to get all of them selected together (except in UVPLT). Note that the selband and selfreq adverbs overide the freqid selection. However, any ambiguity must be resolved by freqid.
Each freqid has one logical row in the FQ table. For each simultaneous frequency (IF) contributing to the freqid, the logical row has an offset in Hz from the reference frequency in the header, a channel width, a total bandwidth and a sideband indicator. Thus, the logical row is multi-dimensional; there are as may actual rows in the logical row as there are simultaneous frequencies (IFs).
Last update : 20/03/96
1