Dynamic Observing Time

All proposers will receive an email with the disposition of their proposal about three months after the proposal deadline. General information from the EVLA/VLBA Proposal Selection Committee (PSC) can be found at http://www.aoc.nrao.edu/~schedsoc/covermemo.shtml . If your application for observing time has been approved by the PSC, the PSC communicates this to you at the top of the disposition, followed by the individual referee reports. You might read something like:

Proposal status (January 1, 2010):
Approved for dynamic scheduling at priority 5.

This line includes at least two important (obvious) pieces of information:

• Your application is approved for dynamic scheduling.
• Your application is ranked in the approved-proposal pool at priority "5".

Following you will see the breakdown in observing sessions, something like:

Current time allocation:
Up to 5.0 hours dynamically scheduled in D configuration.

Time requested:
1 times 2.5 hrs in D config centered at 6.0
1 times 2.5 hrs in D config centered at 21.5

That is, you are expected to submit SBs that are formatted to be selected for observing without any modifications only moments before the actual observation takes place. In the particular example above, you would submit SBs with an LST range roughly centered on your target sources (which are around 6h and 21.5h), adding up to 5 hours of observations in the D configuration. The breakdown may be more complex, more specific for LST ranges, than the above example. The default treatment of SBs in the OPT is to assume dynamic scheduling (the other possibility is fixed-date scheduling). For dynamic scheduling, the SBs must be in LST durations with the total time of each SB being an integer number of 30 minutes (or slightly less) in LST. Longer blocks will be cut short during observations, meaning that you may loose the last part of your schedule without any control (which would be unwise). Some hints specific to dynamic scheduling are given below, and more about the actual scheduling can be found in the OPT manual part of this document.

You are competing with other proposals for the available dynamic time in a trimester. You now have a rough indication of your proposal's priority compared with those other proposals. To gauge the pressure on dynamic time as a function of LST, consult the pressure histograms for the trimester at http://science.nrao.edu/evla/sched/schedsoc.shtml . Figure A.1 shows an example for the D configuration that starts on 2010 March 1 and ends on May 24. The time available per LST hour is shown by the thick black line. Maintenance, software and approved fixed-date proposals cause the black line to be less than the total number of LST days in the configuration and also to vary with LST. The figure shows that the D configuration is oversubscribed for LSTs ranging between 3h and 19h. For example, a SB for a priority 9 proposal is very unlikely to be observed in this LST range. But if that SB could also be observed at, say, an LST of 20h, you can increase the likelihood of it getting selected by allowing this option in the SB details.

Figure A.1: Pressure on the dynamic time for the D configuration (2010 March 1 to May 24). Color codes show the priorities of proposals approved for dynamic scheduling, but excluding triggered transient proposals that have targets at unknown sky locations. Priority 9 proposals have the lowest probability of being observed.