Observing
with UltraDAS
This page is part of the ING manual INS-DAS-29,
Operations manual for UltraDAS
Starting up
Normally, the observing system will already be running when you come to
the telescope to observe. The system is usually started in the early afternoon,
when the technical checks are done. If you need to start the system yourself,
please read the main start-up sequences.
Access to the system; user interfaces
UltraDAS is driven from the system
computer in the telescope control-room. There is a command-line interface,
which also serves for running observing scripts, and various graphical
displays; these controls are all described in the section
on user interfaces, below. Some instruments (e.g. the INT wide-field
camera) provide graphical user interfaces which include UltraDAS functions;
these GUIs are described in the separate manuals for specific instruments.
The commands
UltraDAS main operations are defined as commands in a Unix shell; see the
command-line
section, below, for a summary. See the command
dictionary for details.
Readout windows
A readout window, also known as a region of interest, defines a sub-set
of the detector pixels to be read out. By reading out one window or a set
of windows instead of the full frame of the detector, the speed of readout
is increased and the volume of data is reduced.
Windows are supported in UltraDAS from system s9 onward (s8 does not
have them). See the separate page on windowing
for more details. You may also need to see the section on co-ordinate
systems.
Runs and run numbers
Each run - that is, each observation invoked by a single-observation command
such as run or each cycle of a multiple-observation
command such as multrun - has a run number
that is unique to the telescope in question. Run numbers are not reset
to one when a new observer comes to the telescope. (The current sequence
at the INT was started from one when the first Unix DAS was introduced
in 1994. The numbers are currently in six figures.) The run-number sequences
for different telescopes are independent and tend to overlap.
Even glance and scratch
observations take run numbers from the sequence: this makes it easier to
convert them later to archiveable runs. Hence, using glance
or scratch leaves a gap in the sequence
of your run numbers. Similarly, an observation that you abort, or one which
dies before its time, has already taken a run number so causes a gap in
the sequence. Don't worry about the gaps: they do not upset the data handling.
Integration timing
Integration time is straightforward for most CCD observations but various
subtleties arise when using IR devices or shutterless exposures. The
integrations
and exposures section describes the various modes and explains how
the recorded timings are derived.
Data storage for observations
Raw data of observations are first stored by UltraDAS in memory, then saved
to magnetic disc as FITS files. Somewhat later, the files on disc are archived
on CD-ROMs. Observers make data tapes to take away starting with the FITS
files on the magnetic discs. Details of the storage, particularly of the
raw-data discs, are discussed below.
The automatic image-display
The version of UltraDAS in s9.1 doesn't provide an automatic image-display.
This feature has been withdrawn until we find out how to do it properly.