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Enter the control and performance parameters

The final technical specifications of your Science Goal are entered in the Control and Performance panel (see Fig. 3.9). The Configuration Information section displays information on the array configurations planned for Cycle 2, and uses the representative frequency defined in the spectral setup to calculate the Synthesized beamsize and the Maximum recoverable scale of the observations.

In the Desired Performance section you can define and check technical details of the observations using the following fields (fields displayed in red must be filled):

Desired Angular Resolution: your choice should be guided by the synthesized beamsizes corresponding to the most compact and most extended configurations available in Cycle 2 as displayed in the Configuration Information. The value entered cannot be smaller than the synthesized beam size of the most extended configuration, and cannot be larger than twice the synthesized beam size of the most compact configuration. You can input the angular resolution in arc-seconds or a fraction of the main beam size.
Largest Angular Structure in source: select whether you are observing a point source (this means the source is unresolved even in the most extended configuration) or an extended source. For the latter choice you will be prompted to specify the largest expected angular scale you expect to recover. Together with the angular resolution, this will be used to define the array configuration(s) necessary to achieve your scientific goals. The input units are the same as for the angular resolution.
Desired sensitivity per pointing: you should enter the sensitivity required for the most restrictive line/continuum observation to achieve the scientific aims of the Science Goal, and if relevant mention the sensitivity for the remaining lines/continuum in the technical justification. In the case of a rectangular field mosaic you should specify the sensitivity required over the mosaic, not that for individual overlapping pointings.
Bandwidth used for Sensitivity: for continuum observations, this field is automatically set to AggregateBandwidth. For spectral line or spectral scan observations you can pick one of six choices given in the dropdown menu:

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RepresentativeWindowBandWidth: the bandwidth of the spectral window chosen as the representative spectral window (and containing the Representative Frequency) in Step 3.5
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RepresentativeWindowResolution (default): the (Hanning-smoothed) spectral resolution of the representative spectral window, taking into account spectral averaging
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AggregrateBandwidth: the summed bandwidth of all your selected spectral windows
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LargestWindowBandwidth: the bandwidth of your widest spectral window defined
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FinestResolution: the finest (Hanning-smoothed) resolution of any spectral window, taking into account spectral averaging
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User: a bandwidth of your choice (useful if you are intending to smooth your data after observation to achieve a certain S/N)

Figure 3.9: Control and Performance editor pane and the Time Estimate box.
Image fig10

Figure 3.10: The time constraints interface and Time Estimate box for the example of Multiple Epochs.
Image fig11

Do you request complementary ACA observations: based on your previous input, the OT will make a recommendation on whether you need additional ACA observations if you press the Suggest button. The ACA comprises the 7-m Array as well as the Total Power (TP) Array for observing modes where the TP Array is offered. You can choose to override the recommendation of the OT, but should carefully justify your choice in the technical justification. Note that the ACA cannot be used with the most extended 12-m configurations alone as this would result in a gap in the baseline coverage. If both high spatial resolution and a large spatial scale are needed, the OT will suggest two 12-m configurations as well as the ACA (the number of 12-m configurations can be seen in the Time Estimate pop-up window as well as on the summary sheets see Step 3.10).
Science goal integration time estimate: The Time Estimate button will estimate the total time required to achieve the desired sensitivity goal on the 12-m antennas, including calibrations, multiple pointings, and overheads (see Fig. 3.9). In the event that two 12-m configurations are needed to provide sufficient baseline coverage, the time breakdown will be calculated for the more extended of the two, while the time required for the more compact configuration will be calculated from the former using a fixed multiplicative factor. Similarly, the 7-m Array and TP Array observations are estimated to require a factor of 2 and 4 times the most extended 12-m Array observations respectively. Unless specified otherwise (see below), it is the total time reported here that will be used by the observatory as an estimate of how long your project will take to complete. Note that, for Cycle 2, proposals requiring more than 100 hours cannot be submitted.
Is more time required due to uv-coverage issues? If the time estimated by the OT based on the sensitivity entered is too small to guarantee sufficient uv-coverage you can enter a revised time estimate, which will override the OT value. This will be necessary only in very rare circumstances (e.g. extremely complex but very bright source) and must be fully justified in the technical justification.
Are the observations time-constrained? The OT now has the ability to capture the following time constraints:

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Specific Dates: selecting this radio button allows you to specify fixed time intervals during which your observations should be executed. The observations will be carried out only once in total, within any of the time windows specified. The time estimate computed by the OT remains unchanged.
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Multiple Epochs: here you can define multiple visits for your Science Goal. The timing constraints of the individual visits are specified in terms of arbitrary, fixed or relative time intervals (see Fig. 3.10). In this case, the observations will be carried out once at each epoch. The time estimate computed by the OT will be multiplied by the number of epochs to yield the total time required for the Science Goal.
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Continuous Monitoring: this option allows you do define one or more visits of a user-defined duration. This is particularly useful for monitoring variable sources, as the OT's sensitivity-based time estimate will reflect the time needed in order to reach the requested S/N per measurement, but not take into account the (longer) time required to characterize the variability. Therefore, the OT's time estimate will be overwritten by the sum of the time entered for all of the visits requested.

Figure 3.11: The technical justification editor.
Image fig12

In Cycle 2, there are limitations to the scheduling of time-constrained observations. In particular, constraints specifying a time window of less than two weeks may not be feasible, and any form of time constraint immediately implies that only one 12-m configuration (no ACA) is allowed. Please see the Proposer's Guide for more details. In general, time constraints must be fully justified in the Technical Justification.

You can use the Sensitivity Calculator button in the Toolbar to bring up a pop-up window that allows you to experiment with the integration time estimated to achieve a given sensitivity for a given setup. By default, the setup is appropriate for Cycle 2 capabilities. Note that any parameters entered here are not reflected in the Control and Performance page. The integration time computed from the Sensitivity Calculator refers to just one pointing for the science target and does not take into account calibrations or other overheads.


next up previous contents
Next: Enter the Technical Justification Up: Proposal creation and submission Previous: Select the calibration strategy   Contents
The ALMA OT Team, 2014 May 21