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USNO-B1 Subset &UCAC2 Stellar Data in TheSky6
BackgroundTheSky6 Professional Edition includes the complete UCAC2 stellar catalog (48,330,571 stars), and a subset of the USNO-B1 containing about 15 million stars. When TheSky6's was first released, the UCAC2 catalog was only complete to approximately 40 degrees declination; the incomplete regions are filled using a subset of the USNO-B1 dataset, which is not as accurate. (Note that both are still more accurate than the Guide Star Catalog.) The complete USNO-B1 80 gigabyte catalog is too large to distribute, but it can be downloaded from the web and used with TheSky6. UCAC3?Software Bisque typically adds support for new astronomical databases to TheSky. However, there's no additional information about UCAC3 support at this time.
The USNO A2.0 catalog, although still supported by TheSky6 Professional Edition, is considered obsolete by the IAU, and should not be used to perform astrometry when submitting positional information. Please visit the Software Bisque web site for more details on USNO B/UCAC2 details.
By utilizing the newer and more accurate USNO-B1 data along with the UCAC2 the astrometry performed by TheSky/CCDSoft is often five times more accurate than using just the GSC/Hipparcos/Tycho-2, GSC. And even much better then using the less accurate USNO A2.0 stellar catalogs (either the single CD of 54 million or even the 11 CD's of 526 million stars) because of the limitation imposed by the accuracy of the catalogs.
Note that for most amateurs the 1 billion stars found in the complete USNO-B1 dataset is simply overkill (SEE BELOW) for performing astrometry in the first place. Based on my own personal experience the additional data is not necessary 99% of the time. CCD detectors today are much larger then they have been in the past so fields of view have become quite large often a half a degree to more than 1 degree.
Plotting only the UCAC2 data in TheSky6 Professional edition. View | Catalogs/Astrometry Now the "incomplete region" above 40 degrees declination is clearly visible. Incomplete region
above ~40 degrees declination Now disable all but the USNO-B1 subset USNO-B1 subset (about 15 million stars) Now both the UCAC2 stars AND the USNO-B1 subset Astrometry using TheSky6 and CCDSoftThe following is an average size aperture scope a
Celestron 11 inch f/10 OTA and an
SBIG ST-9E CCD camera yielding a field
of view of 13 arc minutes square. Again, this is a moderate size field for
most amateurs today allowing for good astrometric solutions to be made. Good astrometry being well under the required 0.5 arcseconds
and often under 0.25! Note when using the 1 billion stars found in the complete USNO-B1 dataset the stars will not display until the field of view is less than about 4 degrees. Why? Because the display would be saturated with so many stars and the plotting becomes much slow when using the currently non optimized version of this data. Sufficient number of stars Check out the Astrometry page<-- Click here for complete details on how to perform accurate sub arcsecond astrometry. Enabling the USNO B1 full 80 GB datasetWarning, the user account must have administrative privileges under Vista/XP to change the file locations! If you have access to the 80 GB of USNO-B1 full dataset locally (it is available for download) you can display this catalog with TheSky6.
NOTES:
View | Stellar Options Data | File LocationsMake sure the Green check mark shows when you "Verify" the path statement. Now enable the USNOB1.0 (80 GB dataset) as shown below. The Green arrow means good to go The USNO-B1 1 billion stars will now plot along with the other stellar data present.
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