ATCA Observing
Remote observing with the ATCA is the default mode of observing, but it is also possible to observe from the Marsfield Science Operations Centre (SOC) or the Perth SOC. It is also possible to observe on-site at ATCA during business hours, but on-site accommodation at Narrabri is no longer available. There are multiple accommodation options in the town of Narrabri, about 20 min drive from the observatory site. We advise making any travel arrangements well in advance of your observing run.
Array configurations
At least one 6km configuration, a 1.5 km configuration, a 750 m configuration and all the H168, H214 and H75 hybrid configurations will be offered during the semester. Configurations will only be scheduled if there is sufficient proposal demand for them.
Rapid response observations
We welcome NAPA proposals for rapid response observations (within ~10 minutes of an alert). A rapid response mode for the ATCA will soon be in operation with BIGCAT. Proposers seeking to use this mode must contact Jamie Stevens (Jamie.Stevens [at] csiro.au) to discuss triggering options and requirements.
BIGCAT correlator modes
The new BIGCAT backend provides four 2 GHz IFs to give 8 GHz contiguous bandwidth (with the exception of the 1-3 GHz receiver band which is limited to 2 GHz). This is the standard mode to be used for most continuum observations.
BIGCAT is a highly flexible, GPU-based software correlator capable of supporting almost any required spectral resolution. To simplify scheduling and provide clear guidance for observers, the observatory offers a set of correlator modes that we believe can cover most science use cases. Custom configurations can also be accommodated—within data-rate limits—and prospective users are encouraged to contact observatory staff well ahead of proposal deadlines to discuss specific requirements.
All ATCA proposals will need to create new observations tables to reflect the new BIGCAT observing modes. If you have an existing observations table that specifies CABB observing modes, you may upload it to the OPAL observations table editor and update it with the new BIGCAT modes.
Example BIGCAT modes:
- Continuum mode: 1 MHz channels across 4×1.92 GHz IFs. This is the standard mode for most continuum-polarisation observations.
- Wideband spectral line mode: 18.5 kHz channels across all 4×1.92 GHz IFs
- Zoom modes: Higher spectral resolution across a smaller bandwidth, see below table for examples.
- Tied-Array mode: ATCA used as tied array. Primarily used for VLBI experiments
- Pulsar binning: *note this mode is still being implemented, but is expected to be available in shared-risk mode from early 2027.
- Other: Please use this option in the ATCA observations table and discuss specific requirements in the proposal.
| Name | Resolution over 8GHz | Number of zooms | Zoom bandwidth | Zoom resolution |
| Continuum | 1 MHz | 0 | ||
| Spectral – 74 kHz | 37.037 kHz | 0 | ||
| Spectral – 18.5 kHz | 18.519 kHz | 0 | ||
| Continuum + Zoom 4x2MHz_0.5kHz | 1 MHz | 4 | 2 MHz | 0.488 kHz |
| Continuum + Zoom 4x2MHz_0.06kHz | 1 MHz | 4 | 2 MHz | 0.06 kHz |
| Continuum + Zoom 2x8MHz 2x16MHz 15.625kHz | 1 MHz | 4 | 8 or 16 MHz | 15.625 kHz |
| Continuum + Zoom 1x64MHz 7.8125kHz | 1 MHz | 1 | 64 MHz | 7.8125 kHz |
| Continuum + Zoom 1x128MHz 9 kHz | 1 MHz | 1 | 128 MHz | 9.259 kHz |
ATCA receivers and frequency ranges
The 16-cm band receivers provide an instantaneous frequency coverage from 1.1 to 3.1 GHz (although the usable bandwidth is reduced by typically 30% by Radio Frequency Interference [RFI] — the impact of RFI on the 16cm band can be seen at this webpage.).
The 4-cm band receivers cover the band from 4 GHz to 12 GHz.
In the 15-mm (16–25 GHz), 7-mm (30–50 GHz) and 3-mm (83.5–106 GHz) bands, the four 2GHz-wide intermediate frequency bands (covering approx. 8 GHz) may be tuned within the receiver ranges. In the 7-mm band, all four BIGCAT bands must be above or below 41 GHz, as the receiver sideband changes from lower side-band to upper side-band. More advice on choosing observing frequencies can be found here.
Observing is possible with the standard 15-mm and 7-mm systems on all six antennas, and 3-mm systems on five antennas: there is no 3mm receiver on CA06. Note that the 3mm receivers are ageing and that, as spare parts are limited, or non-existent, component failure in a receiver may not be able to be repaired in a timely manner, or at all.
The ATCA sensitivity calculator provides a means of determining the sensitivity characteristics of observations, and can include the reduction in bandwidth expected due to RFI in the 16cm band.
Millimetre observing
Observing at 3 mm generally starts in May and ends in mid-October. Proposers are reminded that the primary flux density calibrator at 3 mm is Uranus, which in October 2026 will be near an R.A. of 4h12m and declination of +21d00m. Proposals for 3-mm observations that require accurate flux calibration should request time for observations of Uranus (if the array configuration allows). For 7-mm observations with CABB, PKS 1934-638 has sufficient flux density to be used as a flux density calibrator, and should be preferred over Uranus for all projects.
Proposers requiring their own observations of Uranus (at special frequencies, or at a time when their main target has set, for example), should make this clear in the observations table and justification of their proposal. For secondary calibration at 3- and 7-mm, Observatory staff will calibrate a number of bright AGN, spread over the full range of R.A., against Uranus (at 3mm) and 1934-638 (at 7mm) at the standard continuum observing frequencies throughout the semester.
The array is outfitted with Water Vapour Radiometers (WVRs) provided by the University of New South Wales. Experience to date indicates that these units will, in some conditions, allow corrections to the measured phases on longer baselines to be made, improving phase stability and sensitivity. Interested mm-wavelength observers will be able to use this capability during 2025OCT. Details of the system are available at the WVR webpage.
Further information
The Australia Telescope Compact Array User Guide describes how to apply for observing time, make a schedule file, and carry out observations with the ATCA.
Target of Opportunity and NAPA (non A Priori Assignable) proposals
For further information contact the ATCA System Scientist, Jamie Stevens (Jamie.Stevens [at] csiro.au).