[News] Announcement: Release of Report on Astrometry in Astro-WISE
John P. McFarland
mcfarland at astro.rug.nl
Thu Mar 27 23:57:58 CET 2008
The Astro-WISE Astrometry Report is released!
ABSTRACT
The current status of astrometry in Astro-WISE is explored. This includes
the underlying mechanisms, procedures, performance, and accuracies of both
the local and the global astrometric solution, as well as the improvement
from the local to the global solution. Using all currently Astro-WISE
processed data from the WFI instrument on the MPG/ESO 2.2m telescope (24512
frames, more than 3000 exposures), we show that the overall accuracies are
consistent with and due to the precision of the USNO-A2.0 reference catalog
(0.3 arcsec RMS and 1 arcsec systematic) for the local solution and are
approximately 0.04 arcsec for the global solution. In addition, it is found
that the precision of the underlying software (SExtractor, LDAC, SWarp) in
extracting sources, applying solutions, and regridding frames to 0.200
arcsec per pixel is of the order 0.02 arcsec RMS. The performance of the
local solution has a virtually 100% success rate with respect to the
underlying software, a 98.0% success rate with respect to the quality of the
data, and 96.4% success rate with respect to the quality of the solution.
The predicted precision of any astrometric solution is identical to the
actual precision, and this result is repeatable to a level of up to 0.085
arcsec RMS for the local solution and 0.074 arcsec RMS for the global
solution using the extra information in a dither. Finally, the improvement
of the astrometric solution from local to global shows an average increase
in precision of a factor of two, from 0.10 arcsec to 0.054 arcsec, in
2-dimensional RMS.
NOTE
The results in this report were created using the new release of astrometry
software in Astro-WISE (see accompanying News release). Both the Python
layer and LDAC C-programs have been updated in the current version of the
Astro-WISE Environment. Due to improvements in this new release, results
relying on astrometry should be reprocessed where necessary, especially
those relying on global astrometry. Reprocessing can be done manually
through the command-line interface, or in a more automated fashion with the
Target Processor (process.astro-wise.org).
This report can be accessed from the Astro-WISE main page at:
http://www.astro-wise.org/
or directly at:
http://www.astro-wise.org/Public/Astro-WISEAstrometryReport.pdf
--The Astrometry Tiger-Team
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