NRAO supplies a pipeline data calibration for all continuum observations between 1.4 and 15 GHz. This includes amplitude, delay, delay-rate, and phase calibration. Users who would like to request additional assistance should specify it in their proposal or else contact Mark Claussen at least 3 weeks before the time of the observation.

Tables that can be used to perform much of the calibration of VLBA data are extracted from VLBA monitor data and appended to the correlator output FITS files. There is no longer any need for observers to prepare input files for various types of calibration, unless telescopes in addition to the VLBA, VLA, GBT, Arecibo and Effelsberg are used. The supplied tables are as follows:

• TY table: system temperatures measured every 1-2 minutes

• GC table: a-priori VLBA telescope gains

• PC table: extracted pulse-calibration amplitudes and phases

• FG table: flagging information from individual telescopes

• WX table: weather information from stations

Note that the non-VLBA telescopes may not have all desired information (e.g. FG or PC tables).

For more information about application of these tables, see Operations Memo No. 34. For detailed instructions on all aspects of calibration, see A Step-by-Step Recipe for VLBA Data Calibration in AIPS.

Introduction Why use the VLBA? How to propose Proposal selection: refereeing and observing allocation Schedule preparation Observations, correlation, data validation, and distribution Calibration Final imaging and analysis Staff collaboration, financial support for data reduction, scientific results and publications, graduate student programs

The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.