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 Tytuł: CCD Astrograph Catalog (UCAC3)
PostNapisane: środa, 16 grudnia 2009, 22:47 
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Dołączył(a): poniedziałek, 24 sierpnia 2009, 14:27
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Dziś otrzymałem przesyłkę z Departament of the Navy U.S. Naval Observatory z Waszyngtonu przesyłkę z trzecią najnowszą wersją katalogu CCD Astrograph Catalog (UCAC3) zawierającą dokładne pozycje gwiazd do 16 wielkości gwiazdowej. Jak ktoś jest zainteresowany kopią zapraszam na stragan. Dwie płyty DVD.
Pocztą wysyłam tylko dla osób które rzeczywiście skorzystają z tego.

===============================================================================================

The third U.S. Naval Observatory CCD Astrograph Catalog (UCAC3)

Table of contents

1) Introduction

2) Summary of the project
a) Observations and instrumentation
b) Reductions of UCAC observations
c) Computation of proper motions

3) Properties of the catalog and important notes for the user
a) Sky coverage
b) Completeness
c) Reference frame
d) Magnitudes
e) Additional photometry
f) Non-stellar data
g) Provided utility software
h) Arrangement of the data files
i) Star identification numbers

4) Files contained on the DVD
a) Main catalog data
b) Other files

5) Data formats
a) Main catalog zone files
b) Other files

6) Description of utility software

7) Acknowledgments

8) References

======================================================================

1) Introduction
---------------
This is the "readme" file of the third U.S. Naval Observatory CCD Astrograph Catalog, UCAC3. This data release is available free of charge on a double sided DVD or through astronomical data centers.

UCAC3 is a compiled, all-sky star catalog covering mainly the 8 to 16 magnitude range in a single bandpass between V and R. Positional errors are about 15 to 20 mas for stars in the 10 to 14 mag range. It is supplemented by proper motions and SuperCosmos and 2MASS photometric data, as well as various flags.

The proper motions of bright stars are based on about 140 catalogs, including Hipparcos and Tycho, as well as all catalogs used for the Tycho-2 proper motion construction. Proper motions of faint stars are based on a re-reduction of early epoch SPM data (-90 to -10 deg Dec) plus Schmidt plate data from the SuperCosmos project (down weighted due to systematic errors of order 100 mas). The proper motions of faint stars (R >= 13.5) therefore should be used with caution. The unpublished plate measure data from the AGK2, the Hamburg Zone Astrograph, the USNO Black Birch Astrograph, and the Lick Astrograph have considerably contributed to improve proper motions for stars mainly in the 10 to 14 mag range (down to the UCAC3 limit for Lick data); however, these
data do not cover all sky.

UCAC3 features a number of major differences with respect to UCAC2:
- complete sky coverage
- re-reduction of the pixel data with better modeling
- double stars are resolved to the limit of the data
- significantly improved photometry from CCD data
- slightly deeper limiting magnitude with larger number of stars/area
- reduced systematic errors of CCD observations
- the addition of several new catalogs for improved proper motions
- photometry in the B, R, and I bands from the SuperCosmos project
- minor planet observations have been sorted out
- identification of more high proper motion stars
- match with 2MASS extended sources and LEDA galaxies

A UCAC4 release is anticipated in the future. The plan is to utilize a new reduction of the NPM plate material and benefit from global iterative solutions to further reduce possible systematic (zonal)
errors and provide a strong link to the extragalactic reference frame. The UCAC4 release also might make individual positions at observational epochs public, and may serve pixel data as well.

Additional details will be published in the upcoming release paper (Zacharias et al. 2009) and in several technical papers describing details of the reduction procedures and results. For the latest
updates see http://www.usno.navy.mil/usno/astrometry . The release paper should be sited whenever UCAC3 data is utilized. Requests for the data DVD should be sent to ucac3@usno.navy.mil, technical questions can be addressed to nz@usno.navy.mil . The DVD will be sent to all addresses on the UCAC2 distribution list as soon as our resources allow.

2) Summary of the Project
-------------------------

2a) Observations and Instrumentation
------------------------------------
The UCAC is an observational program, using the U.S. Naval Observatory Twin Astrograph and a 4k by 4k CCD camera, covering just over one square degree per frame with a scale of 0.9"/pixel. The red-corrected, 20 cm aperture, 5-element lens of the astrograph provides a 9 degree (diameter) field of view (designed for photographic plates), thus only a fraction is utilized with our CCD camera, centered on the optical axis.

The CCD is a thick, Kodak device with 9 micrometer pixel size. The camera, made by Spectral Instruments, is Peltier cooled to -18 C. The raw data are severely affected by a low charge transfer efficiency (CTE) of our otherwise cosmetically excellent CCD chip. To mitigate this problem, a relatively warm operating temperature is used, causing a significant dark current.

Observations started in January 1998 at Cerro Tololo Interamerican Observatory (CTIO) in Chile, where the entire southern sky and about half of the northern sky were observed. In October 2001 the instrument was moved to the Naval Observatory Flagstaff Station (NOFS) in Arizona where it completed the northern sky in 2004.

A 2-fold, center-in-corner overlap pattern was adopted on a 0.5 degree grid, starting at the South Celestial Pole. Each field was observed with both a long (100 to 150 sec) and a short (20 to 30 sec) exposure. Extensive quality control routines led to the rejection of over 15% of the frames taken. All raw (pixel) data were saved and continue to be archived.

Observations were made in a single bandpass (579-642 nm), thus the UCAC magnitudes are between Johnson V and R. No attempt has been made to obtain high quality, photometric data from the CCD observations. In fact, observations were made during nights with thin cirrus clouds. The telescope was actively guided with an ST-4 autoguider mounted behind the second, visually-corrected lens of the twin-astrograph. Operation was automated using a PC and a single board computer. An HP-Unix workstation was used for on-line reductions to obtain quality control statistics in near real-time.

2b) Reductions of UCAC Observations
-----------------------------------
The UCAC3 positions of the CCD observations are based on the Tycho-2 reference stars, similar to the UCAC2 catalog. However, the 2MASS was utilized to probe for systematic errors in the CCD data, particularly magnitude equations and coma-like errors caused by the poor CTE of the detector. Image centroiding is based on a modified Lorentz profile model which matches the observed PSF better than a Gaussian function. For details, please see upcoming journal papers.

Pixel processing included double star fits and real aperture photometry. "Flip" observations (telescope on West and East side of pier for same calibration field) were utilized to fix the overall magnitude equations.

Saturated images of stars were propagated through the output catalog, so UCAC3 contains many more bright stars than UCAC2. However positional results are not as reliable as for unsaturated images and the user is urged to pay attention to flags and the meaning of various data columns.

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 Tytuł: Re: CCD Astrograph Catalog (UCAC3)
PostNapisane: środa, 16 grudnia 2009, 22:58 
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Dołączył(a): wtorek, 25 sierpnia 2009, 13:05
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Do 16 mag? Chyba nikt tu nie ma takiego sprzętu. :D

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 Tytuł: Re: CCD Astrograph Catalog (UCAC3)
PostNapisane: środa, 16 grudnia 2009, 23:10 
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Dołączył(a): niedziela, 4 października 2009, 13:48
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Marku chciałbym u Ciebie ten katalog zamówić myślę że jak się rozwinę więcej w astrofoto to mi się przyda do PinPoint i MaxIm DL 5
Mam jeszcze pytanie czy posiadasz najnowszy katalog USNO A2.0 który zajmuje około 7G
a mam problemy ze ściągnięciem a potrzebny jest mi do programu PoleAlignMax, PinPoint, MaxIm DL 5 :)


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