Particularly in support of calibration of absolute polarization angle (EVPA) of VLBA observations, the VLA is performing regular monitoring of common polarized radio sources from 1-50 GHz. This page contains a summary of ongoing calibrator monitoring efforts to aid current and future observation proposing and observation planning.
Monitoring programs can be summarized in three categories:
- Regular monitoring and maintenance of standard calibrators (TCAL0009)
- Monitoring of common secondary and mostly variable polarization angle calibrators (TPOL0003)
- Ad-hoc monitoring of special requested calibrators in support of VLBA observations under various project codes
Standard Calibrator Monitoring under TCAL0009
Since May 3rd, 2019, the VLA is performing monthly snapshot observations of a common set of standard calibrators used for flux density and polarization calibration. The list of sources included in this monitoring and observing bands is summarized in the following table:
| # | Target | Bands | Intent |
|---|---|---|---|
| 1 | J2355+4950 | L-Q | Gain |
| 2 | 3C48 | L-Q | Gain |
| 3 | 3C84 | L-Q | Gain |
| 4 | 3C147 | L-Q | Gain |
| 5 | J0713+4349 | L-Q | Gain, PolLeak |
| 6 | 3C196 | L-Q | Gain |
| 7 | J0217+7349 | L-Q | Gain |
| 8 | J1153+8058 | L-Q | Gain |
| 9 | J1800+7828 | L-Q | Gain |
| 10 | 3C123 | L-Q | Gain |
| 11 | 3C138 | L-Q | Gain |
| 12 | J1419+5423 | L-X | Gain |
| 13 | 3C295 | L-X | Gain |
| 14 | J1419+5423 | L-X | Gain |
| 15 | 3C286 | L-Q | Bandpass, Flux Density Scale, PolAngle |
Secondary Calibrator Monitoring under TPOL0003
Since about February 2018, a regular monitoring of secondary polarization angle calibrators was resumed, that is meant to resemble the monitoring performed in the pre-EVLA era. Currently, such observations are performed in two separate scheduling blocks and observed about every 3 months. Recently, additional targets were added to evaluate potential new standard calibrators in the LST range 16-21 hours.
Current list of observed sources:
| POLCAL_1_v2.2 8 bit / 5.5h | POLCAL_2_v3.0 8 bit only / 5.5 h |
|---|---|
| J0854+2006 (L-Q) | J0136+4751 (L-Q) |
| J0713+4349 (L-Q) | J2202+4216 (L-Q) |
| J0521+1638 (L-Q) | J2136+0041 (L-Q) |
| J0555+3948 (L-Q) | J2355+4950 (L-Q) |
| J0739+0137 (L-Q) | J2253+1608 (L-Q) |
| DA240_North (L-Q) | J0136+4751 (L-Q) |
| J0927+3902 (L-Q) | J0137+3309 (L-Q) |
| J1310+3220 (L-Q) | J0319+4130 (L-Q) |
| J1331+3030 (L-Q) | J0359+5057 (L-Q) |
| J1330+2509 (L-C) | J0542+4951 (L-Q) |
| J1256-0547 (L-Q) | J0521+1638 (L-Q) |
| J1743-0350 (L-Q) | |
| J1602+3326 (L-Q) | |
J2025+3343 (L-Q) | |
| J2148+0657 (L-Q) | |
| J2232+1143 (L-Q) |
Leakage
Angle
User Requested Monitoring
Ad-hoc observations are performed primarily for VLBA users, if targets are not covered by the above monitoring programs. A summary of recent requests are collected here. We attempt to capture such observations also under TPOL0003. In some instances they are also observed under the requested project code and not immediately publicly available.