[News] Announcement: Release of Report on Astrometry in Astro-WISE

[John P. McFarland]

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