Facilities > VLBA > Observing > Dynamic Scheduling Guide

Dynamic Scheduling Guide

by Amy Mioduszewski last modified Apr 22, 2019 by Meri Stanley

Proposal Eligibility

  • Target of opportunity, waiting for occurence.
  • Approved for ToO triggering, this trimester only.
  • Approved for dynamic scheduling, priority 1
  • Approved for dynamic scheduling, priority 2
  • Approved for dynamic scheduling, priority 3

An approved VLBA exploratory proposal will usually have a relative priority below that of any regular VLBA proposal.

Available Dynamic Time

VLBA schedule for the current month shows the available open time. To fill the open time, the most appropriate proposal from the observe files available in the dynamic scheduling queue will be selected. This selection may occur only hours in advance of actual observing, and is based on the proposals' referee ratings and the statuses assigned by the EVLA/VLBA Proposal Selection Committee, as well as on the state of the array, including the weather conditions.

Dynamic Queue Activity

Lists are posted giving titles of all proposals currently in the queue, proposals from the queue recently observed, and an approximate ordering of the top proposals in the queue. The latter list is generated by actually running the dynamic scheduling program, and reporting the priorities things would have if scheduled in the next few days. Occasionally, operations schedules things enough ahead of time that your project cannot be scheduled around what they have committed to in the next three or four days. In that case, your project will not appear in this list.

Preparing Observe Files for Dynamic Time

SCHED User Manual. The following points highlight information specific to the dynamic queue.

  • You must prepare a SCHED keyin file in local sidereal time at PT rather than UT; that is, your keyin file should contain the command LST=VLBA_PT. The time allocated for your proposal is based in Pie Town LST, with the caveat that the VLBA is scheduled with half-hour granularity, so the actual LST range may differ by up to 30 minutes.
  • For some proposals, a range in the number of hours to be scheduled is given. When the observation is scheduled, the minimum duration will be allocated, and then will be extended on either end to the extent permitted by neighboring projects or by media availability. Your SCHED keyin file should cover the entire maximum range. The LST observation times in your file will not be changed, only the date. Late starts will be handled by activating the file when the array is ready and then skipping forward to the observation scheduled for that time. You must ensure that any essential calibration observations (e.g., fringe finders) occur within the minimum duration.
  • Please submit your preferred dynamic constraints with your SCHED keyin file, by editing the form for Preferred Dynamic Constraintsas desired and inserting it at the top of your keyin file (the "!" symbol in the form indicates to SCHED that these are comment lines). Please note:
    • We cannot guarantee that all your preferred constraints, especially those related to weather, will be satisfied when your project is observed.
    • It is rare to have 9 stations with weather appropriate for 1cm or 7mm. So specifying this combination in your preferences will make scheduling difficult, especially for proposals queued at medium or low priority.
  • Please ensure that the correlation parameters you submit with your SCHED keyin file are correct. Once your program has been observed and is being prepared for correlation, we will use the correlation parameters from your SCHED keyin file.
  • For few proposals, a local technical contact person has been assigned. If you have questions about preparing your SCHED keyin file, then please seek advice from that technical contact person. If there is no technical contact assigned please send questions to the HelpDesk and select the VLBA Department.

Example Observe File for Dynamic Time

 The SCHED User Manual contains several examples of dynamic scheduling.

Tactical Considerations

Preferred Dynamic Constraints. You can improve your chances even more by requesting even milder constraints, such as a minimum of 8 stations for observations at 6cm. If your preferences change after you submit your keyin file, then please E-mail a revised form for Preferred Dynamic Constraints to schedsoc@nrao.edu.

Submitting Observe Files for Dynamic Time

Observing files (keyin) should be sent to the data analysts via email to . The data analysts will verify that your keyin file can be used by SCHED to produce the VLBA station control files. Verified keyin files will be inserted into the queue to await scheduling.

  • For programs involving monitoring segments, in which you want to use the same SCHED keyin file (including its dynamic constraints) for every segment, you may submit a generic keyin file and the analysts will insert segment codes as you instruct.
  • Some programs request closely-spaced and multi-epoch segments, with different observing frequencies per segment. We recommend that you start with the highest frequency first and assign it segment code A, then descend across the epochs with the lowest frequency last.