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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 at the top of the panel displays information on the array configurations planned for Cycle 3, and uses the representative frequency defined in the spectral setup to calculate the Synthesized beamsize and the Maximum recoverable scale of the observations.

Figure 3.9: Control and Performance editor pane and the Time Estimate box.
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Image didyouknow The Desired Angular Resolution (AR) and the Largest Angular Structure (LAS) are used together to determine the array configuration(s) the observations can be executed in. PIs cannot explicitly request certain configurations, but should instead make sure that the AR and LAS entered are correct. The array configuration selected for your observations will have baselines long enough to achieve an AR better than that requested, and be compact enough to resolve the LAS. Often this will mean that a number of configurations are acceptable for a given Science Goal. If it is not possible to achieve both the AR and LAS desired with just one 12-m array configuration, the OT will automatically add a second 12-m configuration if possible, and/or suggest use of the ACA. This is not possible for long baselines. For details on which configurations can be used together, please consult the Technical Handbook.
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Image Warning-icon-hi If you enter 0.0 for the LAS, your Science Goal will be scheduled in any configuration that meets the AR requirement. For example, if you ask for an AR of 1.2", you will get this or better (i.e. you may get an AR of 0.5" and your data will be smoothed in the data reduction process.)
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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 is guided by the synthesized beamsizes corresponding to the most compact and most extended configurations available in Cycle 3 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.

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Image Warning-icon-hi Observations requesting very small angular resolutions (i.e. those making use of long baselines) are very inefficient because they need to be heavily calibrated to correct for atmospheric phase fluctuations. Since the array configuration is determined based on the AR defined in the OT, it is possible to inadvertently trigger long baseline observations by entering an AR just slightly smaller than that actually required (e.g. standard B3 continuum observations requiring a 0.34 AR will trigger long baselines, while 0.35 AR observations will not). You can see if the observations defined make use of long baselines in the time estimate pop-up (the number of phase calibrator observations per SB execution will be unusually large, above 25 or so), or by running a validation check (see Section 3.10). Obviously, long baselines should be avoided if they are not necessary to achieve a Science Goal.
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Largest Angular Structure in source: here you should enter the largest angular structure that you wish to resolve in your source(s), which may be different from the actual size of the source. The value entered determines whether you need multiple 12-m configurations and/or the ACA, and therefore has a direct influence on the time estimate (see the Maximum recoverable scale for the 12-m configurations in the Configuration Information table for guidance.). 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 S/N achieved 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. We recommend that the sensitivity requested is good enough to give a 3 detection at the very least, ideally 5 .
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)

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Image Warning-icon-hi Please pay close attention that the Bandwidth used for sensitivity is appropriate for your scientific aims. For spectral line observations we recommend that it is at most 1/3 of the expected spectral line width. Selecting too wide a bandwidth will lower the time estimate, but yield too low a sensitivity.
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Do you request complementary ACA observations: press the Suggest button to see whether the OT recommends/allows ACA observations based on the requested AR and LAS. The ACA comprises the 7-m Array as well as the Total Power (TP) Array. Note that the TP array is not offered for continuum observations and in Bands 9 and 10. You can choose to override the recommendation of the OT, but must carefully justify this in the technical justification. Note that the ACA cannot be used with the most extended 12-m configurations as this would result in a gap in the baseline coverage.

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Image didyouknow In Cycle 3, the OT will differentiate between the need for the 7-m array and the Total Power (TP) array based on the LAS entered, i.e. the TP array will be invoked only if the LAS cannot be recovered by the 7-m array. This is in contrast to previous cycles, where the TP array was automatically included with the 7-m array whenever possible.
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Figure 3.10: The time constraints interface and Time Estimate box for the example of Multiple Visits.
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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 3, proposals requiring more than 100 hours cannot be submitted.
Override OT's sensitivity-based time estimate If your Science Goal is not sensitivity driven, but instead requires a certain time (e.g. for a monitoring experiment) you can choose to override the OT's time estimate. The time entered should be the total time (including calibrations and overheads) for the more extended 12-m configuration needed; time estimates for the ACA are the automatically calculated by the OT.
Are the observations time-constrained? The OT now has the ability to capture the following time constraints:

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Single Visit: 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. You can manually Add time windows individually, or Import a list of time slots from an ASCII file. See the Control & Performance section of the ALMA OT Reference Manual for the format required.
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Multiple Visits: 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). Here, the observations will be carried out once for each visit specified. The time estimate computed by the OT will be multiplied by the number of visits.

Figure 3.11: The technical justification editor.
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Image didyouknow Selecting Tool in the OT menu gives you access to a number of useful tools to help you better plan your observations. You can use the Sensitivity Calculator to bring up a pop-up window that allows you to experiment with project execution times and sensitivities, the Project time summary to give a time and data rate summary, and generate printable and pdf summaries of individual Science Goals as well as the project.
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next up previous contents
Next: Enter the Technical Justification Up: Proposal creation and submission Previous: Select the calibration strategy   Contents
The ALMA OT Team, 2018 Sep 25