HRCAM: the high resolution all-sky camera

HRCAM (High Resolution CAMera) is a digital SLR camera (Canon EOS 50D; 15 megapixels) equipped with a fish-eye lens (Sigma 4.5-mm f/2.8) for all-sky coverage on a 1.6 crop sensor. It was first installed in PLATO at Dome A during January 2010. It takes images of the sky above Dome A every few minutes for the purpose of determining the cloud cover, sky brightness, sky transparency, and aurora distribution. It is complimentary in many ways to Gattini, although it doesn't employ the accurately known astronomical filters that Gattini uses, nor can it see as deeply. On the positive side it is capable of imaging clouds when the sun is up.

Snodar An HRCAM image taken on 27 January 2010, just as the Chinese expedition was leaving Dome A. You can see a tractor and five or so sleds at bottom left. The "clouds" at bottom left and top right are tractor exhausts. Snodar is visible at the top, various aerials and towers are visible on the left. The image reaches the horizon in all directions.
Snodar An enlargement of one section of the above image, demonstrating the resolution of the camera and lens, even at the extreme edge of the field.
Snodar The HRCAM instrument. The fish-eye lens is flush with the top, and does not have a window. The reflective metal cover is designed to shed snow, and have low emissivity so that it can be heated efficiently. The holes on the bottom left are for a dehumidifying system. The single Milspec connector provides 24VDC power and a 100Mbps LAN connection. The enclosure includes an ARM-based computer running Linux. The camera is controlled via a USB connection using gphoto2. The instrument is designed to operate down to -80C. The raw images are stored on an array of four 500GB spinning hard-disks inside PLATO. Exposure times vary from 1/2000th of a second to 120 seconds depending on the sky brightness, and are automatically set by the software. Thumbnail images (20kB in size) are sent back via PLATO's Iridium satellite link. Our aim is to use the raw images to extract quantitative information on sky brightness in the three camera filters.


Primary designer and constructor: Daniel Luong-Van
Principal Investigators: Daniel Luong-Van and Michael Ashley

Participating institutions in alphabetical order

UNSW University of New South Wales, Australia