EUROPEAN SOUTHERN OBSERVATORY
|La Silla All-Sky Camera
A S.B.I.G. Model ST-237 and ST-V "All Sky" CCD Imaging Camera System has been
purchased for installation at La Silla, for cloud monitoring. This document
lists the user's requirements.
LED: La Silla Engineering Department
SciOp: La Silla Science Operation Department
SWC: Software and Communication Department
 SBIG ST-237 All Sky fact sheet, SBIG, http://www.sbig.com/sbwhtmls/allsky.htm
 SBIG software page, http://www.sbig.com/sbwhtmls/softpage.htm
The camera should be installed at a place with a fairly clear horizon, under a weather proof enclosure for protection againts day light and bad weather. It is proposed to insall it in the DIMM enclosure, on a small pilar locate out of reach of the DIMM telescope. We leave it to LED to decide if additional protection (e.g. extra case, plexiglass mini-dome) is required.
The camera line/cols must be aligned within a few degrees with the NSEW direction - this must be adjustable.
The camera is controlled by a standard, low-end Windows PC, that should be located next to the camera (ie within lenght of the cables), with appropriate weather protection (e.g. similar to the ACE box of DIMM).
The total power dissipation of the camera is ~15W , so no special consideration about heat dissipation should be necessary. The PC head dissipation should be considered; if it can affect the image quality of the DIMM, it should be insulated/cooled (sealed rack with water pipe from the ACE box running through it?).
In order to protect the CCD of excessive light during day time, a black cloth or paint should be fitted to the enclosure so that it is above the camera when closed.
The control software must take repetitively 5min exposures (exp. time bound to be adjusted at commissioning). Optionally, the data acquisition could stop during day-time (although it is acceptable to dump the unused data).
The data frames must be stored locally in FITS format (this is done by the standard control software provided by SBIG or available at ).
The local computer should hold 1 week of data, in order to minimize the maintenance (i.e. clean the disk 1/ week). One image is 635kB, so we can expect a data rate of 1.25Gb/Wk. So, any fairly recent disk (eg 9Gb) will do.
The PC must run a FTP server so that the images can be transfered in real time to the WWW server.
On the WWW server, a script
Long term archival of the data is beyond the scope of this project.
In a second time, the control software should be scripted so to automatically adjust the exposure time. In a third step, full photometric solution of the images should be performed, in order to convert the images into exctinction maps. After that, an automatic software for detection of transcient phenomena (planes, meteors, comets, SN, GRB, etc) could be implemented, etc, etc. All these are far beyond the scope of this project.