What is the ESO / ST-ECF DSS application?

The ESO/ST-ECF Digitized Sky Survey [DSS] application is a remote client program that extracts random sky section from the DSS image server installed at ESO. The extracted images are delivered in standard FITS format and contain all header keywords needed to visualize proper celestial coordinates for any pixel position. A client to be installed on your local machine can be downloaded here.
The service is also available through a Web interface. This is best suited for small amount of fields. The purpose of the remote client application is to enable the creation of batch jobs to retrieve at once large number of fields, or to be integrated into other application software, scripts or automated observing tools and telescopes.

The application is based on the original software developed at the Space Telescope Science Institute to retrieve any random part of either:

The ESO/ST-ECF Archive has developed the DSS program further to:

• make it work as network client and
• to include SIMBAD name resolving as an alternative to coordinate-only retrieval.

The DSS application essentially takes coordinates and field of view specifications interactively or from an input file and creates a FITS file that can be viewed, converted or analysed with any astronomical data analysis package.
The ESO/ST-ECF DSS program (version 2.5x) is currently supported on Linux (x86). Older versions (Solaris 8, HP-UX 11, and MacOS X/PowerPC, SunOS 4.1.4 and HP-UX10.20) are no longer supported.

What is the Digitized Sky Survey?

DSS1

The Digitized Sky Survey is a collection of Schmidt plates covering the entire sky. The plates are dated from various epochs within the past 30 years. Those have been scanned electronically and the data has been lossily compressed and made available on CD-ROMs. There are two groups of CDs available (102 CD-ROMs, compression 10x; 10 CD-ROMs compression 100x) from the Guide Star Survey group at the Space Telescope Science Institute. See below for more technical details regarding the production and scanning of the material.

DSS2

In the framework of the preparation of the second version of the Guide Star Catalogue, a lot more plates have been scanned, providing multicolor, full sky coverage at a higher resolution with plates. This data collection is now slowly becoming available at a few selected sites.

More Details

The digitization has been carried out using the STScI scanning microdensitometers resulting in a pixel size of 25 micron (15 micron for the second generation -DSS2).
The plates for the southern data are from the SERC Southern Sky Survey and from the SERC J Equatorial extension. These are deep (3600s) IIIa-J exposures obtained through a GG 395 filter, except for 94 short (1200s) V-band exposures mostly at low galactic latitudes (|b| <= 15 deg) plus 2 plates covering the LMC and 2 very short (300s) V-band exposures, each centered on one of the Magellanic Clouds.
The northern data (dec >= +6 deg) was obtained from the 1950-1955 epoch Palomar Sky Survey. These are deep 103-E exposures obtained through a red plexiglass filter.
The digitized images have been compressed by a factor of 10, on average, and are extremely faithful to the original data both photometrically and astrometrically.
The Second Digitized Sky Survey consists in the higher resolution scans of several more plate collection in the red, blue, visible and near infrared. When complete, these collections will help produce a 2-billion object catalog, with multiple colors and proper motions. The DSS2 scans have similarly been compressed and written onto CD-Rs for distribution to a few selected sites. Each color requires approximately 400 CDs. The ESO/ST-ECF archive has copied those onto DVD-Rs, and migrated them onto magnetic disks.

What is the typical use of DSS?

The most frequent use of DSS is to generate finding charts prior to, or during observing runs. Other applications also involve search for optical counterparts of objects discovered at other wavelengths or any scientific statistical projects, just to cite a few examples.

How to use the stand-alone DSS application?

The stand-alone DSS client application is distributed from this site. After the installation is completed on your machine, following the installation instructions , two scripts are available to access dss fields: "dss1" and "dss2".

DSS1

If used without argument dss1 will be interactive and will enter a loop; displaying a prompt in the following form:
   Enter data for first field: There are two possible sets of user's responses here:

• First possibility: <image-name> <ra> <dec> <X-size> <Y-size> Ex: mystar 1 2 3.4 +5 6 7.8 10 10 will produce a FITS image 10x10 arcminutes and centered on ra=1h 2m 3.4 sec and dec=+5deg 6min 7.8sec.
• Second possibility: [<object name>] <image-name> <X-size> <Y-size> Ex: [m33] m33 10 10 will produce a 10x10 arcmin FITS image centered on the SIMBAD position of Messier 33.
  

  (To conclude the session, please press CTRL^d)

The other option is to use the batch mode: In this case the list of pointings to be retrieved have to be recorded in a file following the syntax above.
For example:
    f001 1 2 3 4 5 6 7 10 10
    f002 8 9 10 -11 12 13.4 7 8
    f003 15 16 17.18 -19 20 21.22 20 20
    etc...

Assuming the file is called dss1.in, the dss1 application has therefore to be called in the following way:
   $ dss1 -i dss1.in
After execution, the following files will be available in the current working directory:
   f00106z6.fits f0020446.fits f00301c9.fits

DSS2

The dss2 scripts works as the dss1, but it takes a mandatory extra parameter: the color. The syntax is otherwise absolutely identical. The batch mode also works, provided 'red', 'blue' or 'IR' has been provided as a first parameter to the dss2 command. For example: $ dss2 blue -i /tmp/dss2.in

Copyright Notice

The DSS program is a modification by ESO/ST-ECF of the "getimage" program which is, together with the data, copyrighted by the Space Telescope Science Institute (STScI Digitized Sky Survey, (c) 1993, 1994, AURA, Inc. All rights reserved).

If the Digitized Sky Survey southern data was helpful for your research work, the following acknowledgment would be appreciated:

Based on photographic data obtained using The UK Schmidt Telescope. The UK Schmidt Telescope was operated by the Royal Observatory Edinburgh, with funding from the UK Science and Engineering Research Council, until 1988 June, and thereafter by the Anglo-Australian Observatory. Original plate material is copyright (c) of the Royal Observatory Edinburgh and the Anglo-Australian Observatory. The plates were processed into the present compressed digital form with their permission. The Digitized Sky Survey was produced at the Space Telescope Science Institute under US Government grant NAG W-2166.