APT Smart Accounting
The Smart Accounting tool in APT should be run after the ensemble of proposed observations has been specified, to update the full proposal's resource estimates and remove excess overheads.
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See also: JWST Observing Overheads and Time Accounting Overview
APT Visit Planner section on Smart Accounting in this Video Tutorial.
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Because of this piecemeal approach, there is the possibility of overestimating the overheads a given proposal requires. Thus, after designing an observing program in its entirety, it is important for all proposers to re-run a full accounting on their proposal to remove any excess overhead charges and obtain a final, improved resource estimate. This step is called Smart Accounting.
The resources shown in the Proposal Information GUI when the proposal is submitted will show up on the printed proposal cover page, and will be the official resource request for the proposal.
The Smart Accounting tool looks at the ensemble of proposed observations in a given proposal and decides which sub-groupings might logically be scheduled together in what is termed as a same scheduling set (SSS). If SSSs are identified, APT can reduce the number of assumed major slews required to support your proposal, and this can have a significant and positive effect by lowering the total resource estimate reported for the proposal. Smaller changes may also be taken into account (for instance, if the number of assumed visit slews or guide star acquisitions can be streamlined), but the reduction in major slew changes assumed will make the largest difference in the total overheads needed. Proposals with observations grouped closely on the sky, with separations less than ~20°, will see the greatest reduction in total time.
Same scheduling sets are a statistical accounting tool and do not guarantee that the set of observations will be grouped by the actual JWST scheduling system. If a set of observations must be scheduled together, use the appropriate special requirements to group or sequence your observations.
How to run Smart Accounting
In addition to the description below, you may find this additional help file useful for reference. Note however, due ongoing development of APT, details of the GUI examples shown may not be current. The instructions shown for Smart Accounting are accurate, however, so the help file may still be useful.
As mentioned earlier, as you have built your observations in APT, the tool attempts to estimate the resources. You may have even run the Visit Planner piecemeal on your observations to check their schedulability. However, once your observations have been completely specified, it is time to run Smart Accounting on the ensemble of proposed observations to see whether charged overhead time can be reduced.
There are a number of ways to run Smart Accounting, one implicit and 3 explicit. The implicit way is to simply select the entire observation folder section of the proposal in the tree editor in APT and run the Visit Planner on the entire set of proposed observations in one pass; Smart accounting is run as part of validating the entire proposal. However, any time an update is made to anything in the proposed observations of an APT proposal, APT will conclude that Smart Accounting is out of date and needs to be run again.
As a proposal is in its final stages of preparation, you may want to have explicit knowledge about when Smart Accounting has been run, so this can be accomplished in several ways:
- Select the main Observations folder in the tree editor and then select the Visit Planner tool in the top menu. This should provide access to the Run Smart Accounting button in the Visit Planner GUI itself (see Figure 1). This button is normally grayed out if less than the total observation folder is specified, and will also remain grayed out if Smart Accounting is current and does not need to be run.
- With the Visit Planner active and green checks indicating all observations are schedulable, select Visit Planner → Run Smart Accounting from the main APT menu at the top of your screen (see Figure 2). This forces Smart Accounting to run at any time the user desires.
- Finally, if APT thinks the accounting is out of date, it provides a reminder on the Proposal Information page next to the listed accounting information. Selecting the Run Smart Accounting button at this location opens the Visit Planner and runs Smart Accounting. See Figure 3.
Depending on the number and complexity of observations in your proposal, it can take some time for Smart Accounting to complete. When it does, you can look at the cover page to see the final resource estimate for the proposal.
A cautionary note: the Smart Accounting step can time out on very large or complex proposals and thus not complete the assessment of the proposal. If you have large link sets with greater than 200 visits (for example a large mosaic), consider breaking it into smaller pieces. If you encounter this problem and cannot resolve it, contact the JWST Help Desk.
Further insights: the Smart Accounting report
After running Smart Accounting, you can view the revised total resource assessment in the proposal cover page. You may or may not see a substantial change, depending on the details of your observing program and how recently accounting has been checked for your proposal. Note that accounting information for each specified observation is also provided in each observing template, showing up as a science and total charged duration, but this information is internal to that observation and does not include the major slews between observations.
Additional details of the APT overhead charges are available in a report that provides a summary of where the tool was able to find economies, group observations into SSSs, and possibly reduce visit slew times. This report shows the before and after overhead estimates broken down by observation and visit.
To access this report, go to the top APT menu bar and click on File → Export... A window similar to that shown in Figure 4 will appear.
Check the Smart Accounting visit sequences box (and click OK) to save the report to your local disk. This will be a flat (ASCII) file that can be viewed with any editor.
Helpful hint: If you want to select more than one entry in the Export ... pull-down menu for outputting to a file, hold down the "command" key (Macintosh) or "control" key (Windows and Linux) prior to each click. The most useful reports are generally the times file, the pointing file, and the Smart Accounting visit sequences file.
Figure 5 shows an abbreviated example of the Smart Accounting report output. In this example for a mosaic, the Smart Accounting tool assessment reduced the resource estimate by roughly 1,900 s by accounting one fewer major slew and reducing the visit slew times for the tiles of an assumed mosaic. The "APT Slew" column lists the "before" numbers, and the "Smart Accounting Slew" column shows the corrected values.
Note: the example in the figure above dates to pre-mission values, when the major slew charge was assumed to be 1,800 s. After in-orbit assessments, this number was changed to 2,100 s, beginning with APT version 2022.7 (i.e., as of Cycle 2 proposing).
Initially, APT charges each new observation with an initial "major slew" assumption, because it assumes that the scheduling of the observation may come from a distant position on the celestial sphere. By looking within a proposal and defining possible observations that could schedule together, Smart Accounting can charge a single major slew for the group and calculate actual (assumed) slews between the members of the group, thus reducing the total slew time charged. This assessment is non-binding in the sense that the actual scheduling system may do something different than assumed by the Smart Accounting algorithm, but overall this method produces a more accurate picture of the resources needed to support a given proposal.