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Control and Performance
One panel at the top of the page shows array and telescope configuration information. This should be used to guide a user in the choice of parameters in the panel below, that control predominantly the time required and whether the ACA is required.
Figure 5.9:
The Science Goal Control and Performance parameters.
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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: Display of the antenna beam size for the 12- and 7-m dishes.
- Longest baseline: The maximum baselines available for the most compact and extended configurations.
- Synthesized beamsize: The synthesised beam sizes for the corresponding maximum baselines.
- Shortest Baseline: The minimum baselines available for the most compact and extended configurations.
- Maximum recoverable scale: The largest scale structures that it is possible to image with the most compact and extended configurations.
The user-entered parameters are the following:
- Desired Angular Resolution: The desired angular resolution (synthesized beam size). Must be between the best resolution achievable (i.e. with the most extended configuration) and twice that achievable with the most compact configuration. The latter allows a modest amount of smoothing during data reduction. Based on this value, the OT will choose an appropriate 12-m array configuration.
- Largest Angular Structure in source: The angular extent of the largest components in the source that need to be imaged.
- Desired sensitivity: The sensitivity aim for each source. If a rectangle has been defined, this value should be what is desired in the final mosaic i.e. including beam overlaps. For ``multiple pointings'', it is the value per pointing.
- Bandwidth used for Sensitivity: Specify which bandwidth should be used to calculate the time required. This is used in conjunction with the desired sensitivity and the Representative Frequency. A number of shortcuts are possible (FinestResolution, AggregateBandWidth, LargestWindowBandWidth) or a user-defined value can be entered. ``FinestResolution'' corresponds to twice the channel spacing i.e. Hanning smoothing is assumed.
- ACA: Based on the user-entered values of largest angular scale and angular resolution, the OT will suggest whether the ACA is required and set the choice automatically. Changing this must be well justified and is not recommended. Note that the ACA cannot be chosen if the two largest configurations (C32-5 and C32-6) are required - which configuration has been chosen by the OT is also reported in this dialogue.
- Time Estimate: At this point, it is possible to request an estimate of how long it will take to achieve the scientific objectives of the Science Goal. This brings up a dialogue that contains a lot of information about the times required and parameters used in their derivation. The times reported include calibration and overheads (hardware and software). The ACA observing time is set to three times that required for the 12-m array.
- Extra time: For observations where sensitivity is not the main goal i.e. flux monitoring, the need for a particular amount of observing time can be indicated here. The amount of time and justification should be given in the scientific and technical case.
- Constrained time: Projects that require particular that the data be observed at particular times can be described here. A basic calendar tool is available.
Next: Phase 2 Program Scheduling
Up: Phase 1 and Phase
Previous: Calibration Setup
Contents
The ALMA OT Team, 2013 Feb 27