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Astronomical Data Analysis Software and Systems VII
ASP Conference Series, Vol. 145, 1998
R. Albrecht, R. N. Hook and H. A. Bushouse, e
Ö Copyright 1998 Astronomical Society of the Pacific. All rights reserved.
ds.
Observing Control at the UKIRT
A. Bridger and G. Wright
Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, United
Kingdom
F. Economou
Joint Astronomy Centre, 660 North Aohoku Place, University Park,
Hilo, HI 96720
Abstract. Observing with the major instruments at the United King­
dom Infra­Red Telescope (UKIRT) is already semi­automated by using
ASCII files to configure the instruments and then sequence a series of ex­
posures and telescope movements to acquire the data. This has been very
successful but the emergence of the World Wide Web and other recent
software technologies have suggested that it could be developed further
to provide a friendlier, more powerful interface to observing at UKIRT.
A project is now underway to fully design and implement this system.
1. Introduction
Visiting observers at the United Kingdom Infra­Red Telescope already auto­
mate much of their data taking via the use of predefined Configs and EXECs.
Using an o#­line preparation system to create these has significantly improved
observing e#ciency, as also has the automatic, on­line data reduction system in
use by one of the main instruments. Experience with the system and also the
possibility of changes in the observing practices at UKIRT (an experiment in
reactive scheduling is in progress on UKIRT, Davies 1996) make it seem nat­
ural to improve the present system, taking advantage of recent developments
in software technology. This paper outlines the project (ORAC ­ ``Observatory
Reduction and Acquisition Control'') that has been formed to implement this
evolution. After briefly describing the existing system an overview of the new
system is presented and a short description of each component given.
2. Background: The Current System
The UKIRT control system consists of three main elements, the telescope con­
trol system, the instrument control system and the on­line data reduction system
(Daly, Bridger & Krisciunas 1994 gives more details). The instrument control
system controls the instrument via its use of Configs and the observing sequence
via EXECs. Although most high­level telescope control is performed by the tele­
292

Observing Control at the UKIRT 293
scope operator (TO) the instrument control task also performs some telescope
control (e.g. ``nodding'') via the EXECs.
A Config is a user­defined description of an instrument setup, stored as
an ASCII file. It includes items such as the filter required, exposure time, etc
for both the target and related calibration observations. An EXEC is another
ASCII file containing a user­defined sequence of observing commands which
control both the instrument and the telescope, e.g. configure the instrument,
take a dark frame, take an object observation, ``nod'' the telescope to sky, etc.
EXECs may also call other EXECs, allowing the reuse of standard EXECs and
the modular building of more complex observing sequences. Both Configs and
EXECs are defined using the UKIRT Preparation System. This presents a simple
menu­based interface and in the case of Configs greatly simplifies the creation
of the files, especially by automating some of the selections (though the user
may override). Observers are encouraged to prepare Configs and EXECs before
reaching the telescope, usually at the JAC.
For the CGS4 near­infrared spectrometer there is also automatic data re­
duction ­ as soon as a new data frame is stored the data reduction system will
reduce it, combining it where required with other data frames. This gives a
rapid feedback of the true data quality to the observer as well as producing (in
many cases) the final reduced data.
Despite its success there are a number of limitations in this system. Bridger
and Wright (1996) proposed to evolve this system into a more fully automated
version. Since then a project has been created with the stated aim `To increase
the observing e#ciency and publication rate of UKIRT'. The approach is based
around making it easier, friendlier and more e#cient to observe at UKIRT:
by providing an easy to use remote preparation system; by providing a more
powerful and flexible on­line data reduction system; and by further automating
the acquisition of data at the telescope. A long­term goal is to produce a system
capable of fully queue­scheduled observing, should UKIRT implement it.
3. ORAC: An Overview
The design is based around the idea that an observation may be defined as con­
sisting of an Instrument Configuration, which tells the instrument how it should
be setup for an observation, a Target Description, to inform the telescope where
to point, and an Observing Sequence, which describes the sequence of telescope
movements and data acquisition commands required to execute the observa­
tion. These components are modular and may be used in multiple Observa­
tion Definitions. Thus Target Description BS623 may be used with Instrument
Configuration Std H Band and Sequence Bright Star in one observation, and
combined with My K Band and Std Jitter to form a di#erent observation.
To this basic definition of an observation are added further components which
describe the data reduction Recipe to be used on the observation and Scheduling
Information which may be used in a more sophisticated observation scheduler.
These components, and the full Observation Definitions, may be prepared
ahead of time (o#­line) or at the telescope. In operation the Observatory Control
System will read them and distribute the components to the various subsystems,
to configure and control the acquisition and the reduction of the data.

294 Bridger, Wright and Economou
3.1. Observation Preparation System
The Observation Preparation System is a replacement for the existing UKIRT
Preparation System. Observers must be able to run it from their home insti­
tution, without the need for detailed software installations. The system will
need to change to reflect changing instrument availability. Both of these suggest
a Web­based application. However, speed of the Web, and the loading on the
server might be problems. Use of mirror sites could help with this, but the use
of automatic software installations and Internet push technology to keep them
up to date might be a better solution. This is the approach taken by the Gemini
group with their Observing Tool (Wampler et al. 1998).
The output of the preparation system will be one or many files forming an
Observation Definition that can be stored along with similar definitions from
the same or di#erent observing programmes to form the telescope's observa­
tion `database'. Initial versions of the database will probably use the existing
combination of ASCII text files and a directory tree structure, for backwards
compatibility. Possible future use of a commercial database will be considered.
It is likely that much observation verification will be done by this system ­
the output of the preparation system should be guaranteed to be able to be per­
formed by the instrument, to eliminate errors at the telescope. The preparation
system will present the user with an astronomer­oriented interface, although its
output may well be at a lower level. It is anticipated that the system's un­
derstanding of the instruments will be codified by a set of rules which will be
maintained by the instrument support scientist, adding to the system robustness.
3.2. Observatory Control System
The Observatory Control System performs the sequencing role between the in­
struments and telescopes and optionally also some of the scheduling of individual
observations. The way in which the components of the Observation Definitions
are to be handled is still to be determined, but the likely approach is to leave the
reading and parsing of a component to the system that requires it ­ for exam­
ple an Instrument Configuration will be read and interpreted by the Instrument
Control System. This considerably simplifies the logic of the higher system.
Other approaches are possible and will be considered.
The Observatory Control System consists of two main components:
. The Observation Sequencer. This task informs instruments of their re­
quired configuration and sequences a set of operations to generate a par­
ticular observation. This can include taking Object and Sky sequences,
mosaicing, nodding and chopping etc. A key aspect is that it will define
a standard, but general, instrument interface to which all UKIRT instru­
ments will need to adhere.
. The Scheduler. This new component in the system is a higher level system
that maintains a queue of Observation Definitions prioritised according to
their scheduling information. Its goal is to intelligently and automatically
handle the correct and e#cient scheduling of the observations, informing
the observation sequencer of the next observation. It will also provide for
monitoring and direct manipulation of the observing queue. The scheduler
is likely to be delivered as a later upgrade to the new system.

Observing Control at the UKIRT 295
3.3. Data Reduction System
This performs automatic on­line data reduction after the raw data frames are
stored. Its current design is based on the concepts of Recipes and Scripts:
. A Recipe is a series of instructions detailing how to perform a (potentially
complex) data reduction operation.
. A Script is a series of instructions on how to apply a Recipe to reduce an
observing sequence using a particular data reduction package.
The user will request a particular reduction sequence by drawing from a
series of observatory defined Scripts and Recipes. Advanced users will be able
to provide their own Recipes and Scripts to reduce particular aspects of their
observations, but it is expected that they will all use standard Recipes to remove
specific instrument dependencies. It is anticipated that the Scripts will be coded
in a standard scripting language, and it is hoped that the actual data reduction
algorithms will be provided by standard data reduction packages. The aim of
this is to reduce the support e#ort at the Observatory, concentrating it on the
automatic aspects of the reduction system. As a side e#ect, all of the actual
algorithms used by the system should already be available to the community,
and users may be provided with the actual Scripts used to reduce their data.
The data reduction system is described in more detail in Economou et al. (1997)
4. Conclusions
A constant driving force on the UKIRT control system is the desire of observers
for greater e#ciency. The ORAC project aims to achieve greater e#ciency whilst
retaining the flavour and flexibility of current observing practices.
Acknowledgments. We would like to acknowledge the scientists and soft­
ware groups at UKIRT and ROE, and the UKIRT telescope operators for many
helpful discussions, and of course the input of many UKIRT observers.
References
Bridger, A. & Wright, G. S. 1996, in New Observing Modes for the Next Century,
ASP Conf. Ser., Vol. 87, eds., T. A. Boroson, J. K. Davies & E. I. Robson
(San Francisco, ASP), 162
Daly, P. N., Bridger, A. & Krisciunas, K. 1994, in ASP Conf. Ser., Vol. 61, Astro­
nomical Data Analysis Software and Systems III, ed. Dennis R. Crabtree,
R. J. Hanisch & Jeannette Barnes (San Francisco: ASP), 457
Davies, J. K. 1996, in New Observing Modes for the Next Century, ASP Conf.
Ser., Vol. 87, eds., T. A. Boroson, J. K. Davies & E. I. Robson (San
Francisco, ASP), 76
Economou, F., Bridger, A., Wright, G. S., Rees, N. P. & Jenness T. 1997, this
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Wampler, S., Gillies, K., Puxley, P. & Walker, S. 1998, in SPIE vol 3112, in
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