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.