Phased VLA Modes for Semester 2013B

by Gustaaf Van Moorsel last modified Jun 05, 2013

HSA proposals for observing semester 2013B can request the phased VLA in conjunction with the VLBA, and for processing only at the Socorro DiFX correlator.  A comprehensive adjunct to the VLA Observational Status Summary, "VLBI at the VLA", discusses the available phased-VLA capabilities, and provides instructions for their use.  This sub-section of the VLBA Observational Status Summary describes only the specific compatible modes between the two instruments.

Phased-array data will be limited to two VLA subband pairs, in any combination of polarizations, but with each pair in different IFs (AC and BD).  Any matching bandwidths available on both the VLA and the VLBA DDC data system described above can be used.  Bandwidths must be uniform within each station, across the entire VLBI array, and throughout the entire duration of the observation. In particular, VLA phasing and VLBI observing must be carried out at the same bandwidth.  Bandwidths narrower than 16 MHz are not expected to be useful in most cases, and have not been tested at this time.  Such observations are therefore available only on a shared-risk basis.

Table 7 shows the available bandwidth options, their recorded data rates, and shared-risk status, for maximum VLA-VLBA sensitivity with four DDC channels on the VLBA.

Table 7:  Phased-VLA / VLBA Compatibility


VLA+VLBA
Shared Risk?

Subbands/Channels:

4
Bandwidth Data Rate
[MHz]
[Mbps]

128 2048 No
64 1024 No
32 512 No
16 256 No
8 128 Yes
4 64 Yes
2 32 Yes
1 16 Yes