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High frequency observing requires good weather. To most efficiently use observing time it is important to observe at high frequency during appropriately good weather conditions and observe at low frequencies during bad weather whenever possible. This requires dynamic scheduling. There are insufficient software tools in place to implement a true dynamic scheduling scheme. Until these tools are available we have attempted to implement a partial or pseudo dynamic scheme. The procedure to be followed is outlined in the following steps.
Initial Creation of the Schedule
- Two separate schedules are made in advance. The four month trimester will be completely scheduled (usually) the month before the start of the trimester.
- High frequency observations (generally observing frequencies greater than 10 GHz) are scheduled for twice their allotted time on paired days. The two days of a pair can be separated by 1 to 7 days, but usually the separation is about two days. Projects which are scheduled as high frequency will be prefaced with a + on the (Primary) monthly graphics schedule along with the 'fixed' scheduled projects.
- Low frequency observations will be scheduled as backup (secondary) projects in parallel with scheduled high frequency observations whenever possible. The low frequency backup schedule has its own (Backup) monthly graphics version.
Daily Schedule changes to Accommodate weather changes
- One of the paired days will go to the high frequency project and the other day will go to the low frequency backup.
- The decision maker will be the primary project's observer. The decision should be discussed and communicated with the GBT scheduler (at the very least) during normal work days and with the operator on weekends and holidays. If desired other staff may be consulted as well.
- The decision will be made by NEW 11:00 am ET each day, including weekends and holidays, for all observing for the next 24 hours starting at 17:00 Eastern time on the day of the decision.
- The decision will be a go or no go for the primary project with no "maybes".
- Email all decisions to both firstname.lastname@example.org and email@example.com.
- On normal work days the scheduler, or his designee in his absence, will be responsible for the communication of this decision to the secondary project observer and the operations staff. The form of the communication will be "in person" (whenever possible) to the secondary project observer and the operator (when in the control room) with a follow up email to gbtops and gbt. On weekends and holidays: The operator will be the focal point of communications. The observers for the high frequency project MUST make their decision by noon and communicate it directly to the operator. The low frequency (secondary project) observer must contact the operator for the decision.
- Last minute changes in the decision (ie to give the high frequency observing time to the low frequency observing program) after the basic decision has already been made would only be permitted by the primary project observer without a 'penalty' when very unusual and unavoidable circumstances arose (for example the receiver broke and could no longer be used). Exceptionally, if the primary project observer has elected not to use the first day due to unacceptable weather conditions, and then the forecast for the second day is also clearly unacceptable, we will consider using the second day for a low frequency proposal (current backup proposal or an alternate), and attempt to reschedule the high frequency proposal for a later date. This decision will be made by the GBT Head of Science Operations and Scheduler.
- Regular proposals which could not be scheduled or completed within one year will be closed. Continuation beyond one year will require submission of a new proposal.
Although this scheme has many shortcomings it seems the best compromise for the present. The procedures will be constantly under review. (last updated - 08/07/07)