VLT Survey Telescope
Announcement of Opportunity

March, 1998

The European Southern Observatory (ESO) and the Osservatorio Astronomico di Capodimonte (OAC) are jointly planning a 2.5-m telescope to be erected adjacent to the Very Large Telescope (VLT) on Cerro Paranal in Chile in the year 2001. This telescope, which has been given the name VLT Survey Telescope (VST), is designed to deliver a field of view of 1 x 1 square degree. More information about the VST can be found on the WWW homepage maintained by OAC (URL:http://oacosf.na.astro.it/vst).

With this Announcement of Opportunity ESO is seeking a partner for the design, construction, and procurement of an optical wide-angle camera which will be installed in the Cassegrain f/5.76 focus of the VST (plate scale: 14.3 arcsec/mm). The project will include:

• instrument housing
• filter storage and exchange mechanism
• filters
• shutter
• detector array
• cryostat
• all control electronics
• the control software
• the data calibration and reduction software
• data quality control tools
• all computer equipment needed for the on-line operation
• complete documentation.

Note that that many, possibly all, components of the camera optics will be provided together with the telescope by OAC.

Design requirements are that

• the detector optimally covers the useful field of view of 1.0 x 1.0 degree²,
• the best seeing at Paranal of about 0.4 arcsec is still adequately sampled (the median seeing is about 0.6 arcsec),
• the wavelength coverage is from 365 to 1015 nm,
• the total weight does not exceed 200-250 kg (this limit is preliminary),
• a minimum of 10 filters can be mounted at a time,
• the filters mounted can be exchanged within less than 1 hour,
• autoguider signals to the telescope are provided by the instrument itself,
• in order to keep the maintenance and operations cost low, the VLT standards are adhered to as much as possible which in particular implies that
  • ESO's FIERA system is used for the controlling of the CCD's,
  • the non-instrument specific part of the VLT control software is used,
  • the instrument-specific control is compliant with VLT standards,
  • the user support, calibration, and data reduction software are compatible with the VLT Data Flow System.

• needs and options for the implementation of a (retractable) atmospheric dispersion corrector,
• tip-tilt (or other) corrections within the instrument to compensate for wavefront tilts,
• optional operation of the CCD's in drift-scan mode,
• obscuration of bright sources,
• options for limited spectroscopic capabilities which, however, should not compromise the quality in imaging mode or dominate the technical complexity.

In exchange for the contributions made, the partner consortium will receive a number of guaranteed nights corresponding to the share of the total cost of the telescope, the instrument, and the operation during the lifetime of the instrument (assumed to be of order 10 years). Contributions can be made in any combination of financial participation, personnel, or ready-made subsystems. But proposals should cover the complete instrument. ESO is ready to provide assistance in all areas and in particular has a strong interest and special expertise for supplying the entire detector system, at actual cost. ESO's general contractual conditions apply.

Interested consortia are invited to send a letter of interest by June 30, 1998 to ESO Headquarters, attention of Dietrich Baade, who can also be contacted for further information (dbaade@eso.org).

Initially, this optical camera will be the only instrument at the VST. However, there is strong scientific interest also in a wide-angle infrared camera. Accordingly, ESO would also welcome resource-based suggestions for the practical realization of such a project.