Phased VLA Modes
HSA proposals can request the phased VLA in conjunction with the VLBA and other HSA telescopes, subject to availability of matching observing systems. Two adjuncts to the VLA Observational Status Summary, "VLBI at the VLA" and VLBI @ the VLA: Scheduling Hints, discuss 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. Any matching bandwidths available on both the VLA and the 4-channel VLBA DDC data system 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 |
