At the top of the page, a panel (not shown for VLBI or Phased Array projects) shows array and telescope configuration information. The configuration information (all calculated assuming the sky-frame equivalent of the Representative Frequency for the first source in the Science Goal) are:
- Antenna Beamsize: The FWHM of both the 12- and 7-m dishes. This roughly sets the field of view of a single telescope pointing. Sources larger than this, or multiple sources spread over a larger area, must be mosaiced together using multiple pointings.
- Number of antennas: The number of atennas assumed for each of the arrays. These numbers are also set by default in the ALMA Sensitivity Calculator.
- Longest baseline: The maximum baselines available for the most compact and extended 12-m Array configurations, as well as the ACA 7-m Array. The baseline lengths are a function of receiver band as the larger configurations cannot be observed at higher frequencies. All baseline lengths are unprojected i.e. they are not a function of source declination. Projection effects are though taken into account when calculating the synthesized beamsize.
- Synthesized beamsize: The synthesized beam sizes for the corresponding maximum baselines. This number is dependent on the source declination, or the average declination if there is more than one source. The best angular resolution is possible when observing a source at the same declination as the latitude of the observatory (
degrees). As the magnitude of the declination difference increases, the angular resolution deteriorates for a given configuration. If the sources have been split into multiple clusters, the value reported for the most compact configuration corresponds to the cluster which produces the largest beamsize. Likewise, the most extended configuration will correspond to the smallest beamsize possible out of all the clusters.
- Shortest Baseline: The minimum baselines available for the most compact and extended 12-m Array configurations, as well as the ACA 7-m Array. The baseline lengths are a function of receiver band as the larger configurations cannot be observed at higher frequencies. All baseline lengths are unprojected i.e. they are not a function of source declination. Projection effects are though taken into account when calculating the maximum recoverable scale.
- Maximum recoverable scale: The largest structures that it is possible to image with the most compact and extended configurations. Like the angular resolution, this is also declination dependent.
The ALMA OT Team, 2024 Mar 01