The UKT14 Queuing System

The UKT14 queueing system software is an adaptation of the SCUBA queueing and sequencing system. It provides the basic tools needed to manipulate entries in a queue throughout the observing session. It does not have the ability to order the queues as do the more complex queueing systems. It is an interface to the JCMT antenna control system and uses the Adam message system for intertask communication.

The parameters for an observation are specified in an observation definition (obsdef) file. In all, about thirty parameters are required for UKT14 photometry. The parameters are read by the sequencing software (SCUCD) as input to a program script for the observation. There are scripts to acquire a source, to setup for a sequence of observations, to point, to focus, to take a sample and to do an auto-sequence. The program scripts are supplied with the queueing system and the observer need not be concerned with its details. However, changes to a script can readily be made by the software group.

Windowing Environment

The queueing system is started up from a Vax or Sun workstation by opening up a window and logging in to the control computer (MWTTEL). A command is entered to automatically create three more windows: one for displaying the queues, another for the UKT14 summary data, and a third window for system messages. Commands to control the queues are entered from the original window.

The queue window shows the leading entries in the queues. Also shown are the last entry sent, the total number of queued entries and the state of the queue (either running, stopped or paused). A total of a hundred entries are allowed in each queue.

The summary window is for the logging of UKT14 observations. There is a one line display for each observation, giving the source name, observation number, airmass, filter, aperture, signal and signal-to- noise.

Queue Management

The queue management system provides for the creation and manipulation of entries in the queues. A queue entry refers to an obsdef file containing the parameters for the observation. The observer is responsible to create and order the queues. In the running state the top queue entry is automatically sent to SCUCD which gets the parameters and sends commands to the antenna control system. The queueing is stopped when an error occurs or paused when a response is required from the observer. Commonly used obsdef files are stored in a system directory.

There are two queues, primary and secondary. The primary queue is where obsdef entries are first made. A macro obsdef specifies multiple observations and it is expanded onto the secondary queue in order to maintain its group quality. There are commands to manipulate either queue. A standard repertoire of commands is available to add, delete, cut and paste to a queue. The observer can select which queue to run with and can start or stop the queues.

Conclusion

In general, the queueing system can improve efficiency because it enables advanced preparation of observations. It also automates much of the commands used in the setup and taking of samples. Thus far the queueing system has been used successfully for the photometry of blazars. The basic development of the system is complete, although enhancements are possible as the requirements for this observing mode become more apparent. It can be used for any beamswitched UKT14 observations (except polarimetry.) It is planned to be used for pointing runs. A likely upgrade will be to run it in a distributed mode using the Adam network for inter-nodal communication, as it will be in the SCUBA system.

The queueing software was originally created by B.D. Kelly, A.C. Davenhall and J. Lightfoot. The sequencing software was created by J. Lightfoot. This author has made modifications to each of these softwares to adapt it for UKT14 (single bolometer) photometry.

If you would like to use the queueing system for your photometry at JCMT, email the author at firmin@jach.hawaii.edu.

Reference:

Oliveira, F.J., The UKT14 Queueing System, in

"New Observing Modes for the Next Century", PASP Conference Series.

Firmin J. Oliveira, JAC

(JCMT Software Engineer)