Projects, Program Blocks, and Scheduling Blocks

A project (an orange P: Project; Figure 1.2) consists of at least one program block (PB, a blue PB: Program Block), which is defined as a collection of observations for a single proposal, using a single telescope or an EVLA array configuration (or a sequence of consecutive configurations). That is, typically a PB does not extend to another allocation trimester; e.g., if you were allocated time for the A array and the CnB array, one PB would be defined for the A array and one would be reserved for the CnB array observations in a following allocation trimester. A PB is made up of at least one scheduling block (SB, a green SB: Scheduling Block), which consists of a sequence of scans (a radio telescope: Radio Telescope): combinations of a timed telescope pointing direction (a source) using a specific hardware and instrument configuration (a resource) in a specified observation mode with a specific intent. Scans may be grouped in scan loops (a looping circle: Scan Loop), or loops (of loops, ..) of scan loops.

For fixed date observing, each allocated time slot will typically be equivalent to a SB. For dynamically allocated observing time, a SB is not necessarily the same as a complete observing run; one can think of an observing run as a random or specific order of several executions of a SB on the sources of interest, whether or not on the same observing day, possibly interspersed with a SB performing flux calibrations, a SB performing observations at a different frequency, etc.

OPT Figure 1.2

Figure 1.2: The PROJECT tree consists of at least one PROGRAM BLOCK (PB); A PB is made up of at least one SCHEDULING BLOCK (SB), which consists of a sequence of SCANS with or without LOOPS of scans.

In general, SBs may be many different snippets of an observing run, i.e., groups of consecutive scans that constitute a complete observation (a PB), but an observing run may as well be defined in a single SB. It depends on what the user finds convenient; for example one can define a template calibration SB on J1331+305 that can be copied to each new PB assigned by the PSC. However, observing time typically is allocated in a multiple of 30 minute LST slots, in which case the user will probably typically schedule a PB in SBs with a maximum length of an integer number of 30 LST minutes. For the final SBs, the ones that through the OPT are submitted for observation, the duration of the observation of the SB is required to be an integer number of 30 LST minutes maximum. This is not necessary for template SBs or SBs that will not be submitted.

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