The JCMT observing queue and recipe sequencer

Abstract

The James Clerk Maxwell Telescope (JCMT), the world's largest sub-mm telescope, will soon be switching operations from a VAX/VMS based control system to a new, Linux-based, Observatory Control System 1 (OCS). A critical part of the OCS is the set of tasks that are associated with the observation queue and the observing recipe sequencer: 1) the JCMT observation queue task 2) the JCMT instrument task, 3) the JCMT Observation Sequencer (JOS), and 4) the OCS console task. The JCMT observation queue task serves as a staging area for observations that have been translated from the observer's science program into a form suitable for the various OCS subsystems. The queue task operates by sending the observation at the head of the queue to the JCMT instrument task and then waits for the astronomer to accept the data before removing the observation from the queue. The JCMT instrument task is responsible for running up the set of tasks required to observe with a particular instrument at the JCMT and passing the observation on to the JOS. The JOS is responsible for executing the observing recipe, pausing/continuing the recipe when commanded, and prematurely ending or aborting the observation when commanded. The OCS console task provides the user with a GUI window with which they can control and monitor the observation queue and the observation itself. This paper shows where the observation queue and recipe sequencer fit into the JCMT OCS, presents the design decisions that resulted in the tasks being structured as they are, describes the external interfaces of the four tasks, and details the interaction between the tasks.

HARP/ACSIS: a submillimetre spectral imaging system on the James Clerk Maxwell Telescope

“…The non time-critical aspects of observatory control, i.e. the setup of the subsystems before the start of each sequence, is under control of the JCMT Observation recipe Sequencer (JOS; see Kackley et al 2004;Rees et al 2002). This is a high-level control system which executes the observing recipe, setting up the many sequences within each recipe.…”

Setting the standard: 25 years of operating the JCMT

“…The critical developments required to allow this include a rotating tertiary mirror in the cabin, and a sophisticated telescope software interface between the telescope, instruments and observer. [22][23][24][25] It has also been a requirement that any instrument commissioned at JCMT must support this shared operational and data-reduction software 26 to maintain the efficiency of these observing interfaces. Fast-switching between instruments has the added benefit of reducing "dead-time" resulting from instrument-related faults, as a time-consuming issue with a particular instrument can be dealt with after switching to a working instrument, which can continue to take data whilst the original problem is resolved.…”

Data Management At the UKIRT and JCMT

“…• A queue that will send translated output to the OCS one observation at a time and realise when an MSB has been completed. 48 The queue then gives an opportunity for the observer to accept or reject the MSB and associate this with any comment on data quality.…”