Astronomy and Astrophysics – Astronomy
Scientific paper
Jul 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008spie.7016e..25c&link_type=abstract
Observatory Operations: Strategies, Processes, and Systems II. Edited by Brissenden, Roger J.; Silva, David R. Proceedings o
Astronomy and Astrophysics
Astronomy
1
Scientific paper
Mauna Kea (4200\,m elevation, Hawaii) is known for its pristine seeing conditions, but sky transparency can be an issue for science operations: 25% of the nights are not photometric, a cloud coverage mostly due to high-altitude thin cirrus. The Canada-France-Hawaii Telescope (CFHT) is upgrading its real-time sky transparency monitor in the optical domain (V-band) into a dual-color system by adding a B-band channel and redesigning the entire optical and mechanical assembly. Since 2000, the original single-channel SkyProbe has gathered one exposure every minute during each observing night using a small CCD camera with a very wide field of view (35 sq. deg.) encompassing the region pointed by the telescope for science operations, and exposures long enough (30 seconds) to capture at least 100 stars of Hipparcos' Tychos catalog at high galactic latitudes (and up to 600 stars at low galactic latitudes). A key advantage of SkyProbe over direct thermal infrared imaging detection of clouds, is that it allows an accurate absolute measurement, within 5%, of the true atmospheric absorption by clouds affecting the data being gathered by the telescope's main science instrument. This system has proven crucial for decision making in the CFHT queued service observing (QSO), representing today 95% of the telescope time: science exposures taken in non-photometric conditions are automatically registered for being re-observed later on (at 1/10th of the original exposure time per pointing in the observed filters) to ensure a proper final absolute photometric calibration. If the absorption is too high, exposures can be repeated, or the observing can be done for a lower ranked science program. The new dual color system (simultaneous B & V bands) will allow a better characterization of the sky properties above Mauna Kea and should enable a better detection of the thinner cirrus (absorption down to 0.02 mag., i.e. 2%). SkyProbe is operated within the Elixir pipeline, a collection of tools used for handling the CFHT CCD mosaics (CFH12K and MegaCam), from data pre-processing to astrometric and photometric calibration.
Cuillandre Jean Charles
Magnier Eugene
Mahoney Billy
Sabin Dan
No associations
LandOfFree
SkyProbeBV: dual-color absolute sky transparency monitor to optimize science operations does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with SkyProbeBV: dual-color absolute sky transparency monitor to optimize science operations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and SkyProbeBV: dual-color absolute sky transparency monitor to optimize science operations will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-793581