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: http://www.adass.org/adass/proceedings/adass99/P1-07/
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clear aperture | 206 | mm |
focal length | 2057 | mm |
plate scale | 100 | "/mm |
number of lens elements | 5 | |
spectral bandpass of lens | 550-710 | nm |
Airy disc diameter (610nm) | 15 | ![]() |
usable flat field of view | ![]() |
degree |
After one month of setup and testing
the southern part of the survey started in February 1998 at Cerro Tololo
Inter-American Observatory (CTIO).
The project is scheduled for 3 years to completely
cover the area from the South Celestial Pole to about +20 degrees declination.
Another 2 years will be required to complete the entire sky from a Northern
Hemisphere site.
Through September 1999 over 30,000 fields have been taken
in a 2-fold overlap pattern, covering over 70 of the Southern Hemisphere.
For details on the procedures and software see (Zacharias & Zacharias 1999).
number of pixels | 4096 x 4096 | |
field of view | 61 x 61 | arcmin |
pixel size | 9.0 | ![]() |
pixel scale | 0.9 | "/pixel |
spectral bandpass used | 579-642 | nm |
filter replaces window | ![]() |
optical quality |
readout | 14 | bit |
readout noise | 13 | ![]() |
full well capacity | 85,000 | ![]() |
operating temperature | ![]() |
C |
limiting magnitude | ![]() |
2 min. |
A preliminary astrometric catalog, UCAC1, is being produced, containing
positions of 30 million stars.
First results are presented in Figure 1.
These data will be supplemented by proper motions using the USNO A2.0 catalog.
These low precision proper motions (
10 mas/yr)
will be improved by about a factor of 2 in the near future, when the NPM and
SPM data are included.
A comparison of UCAC data with other catalogs (Figure 2) shows
the large improvement in accuracy it the high star density region.
A public release of UCAC1 is expected by the end of 1999;
see http://ad.usno.navy.mil/ad/
for availability.
Some properties of the catalog are summarized in Table 3.
overlap pattern fields | 2-fold | center in corner |
exposures per field | 1 short | 1 long |
exposure times | 20 ... 150 | seconds, guided |
coverage |
![]() |
|
epoch of observations | Feb 1998 | ![]() |
average density | 2000 | stars / square degree |
total | 30 | million stars |
catalog accuracy | 20 | mas, R = ![]() ![]() |
70 | mas, R = ![]() |
|
proper motions | ![]() |
mas/yr |
number of CCD frames | ![]() |
|
raw data so far | 1.5 | TB compressed FITS |
backup on | 700 | exabyte tapes |
2,400 | CD-ROMs | |
detection output | 7 | GB compressed |
astrometric catalog | 1 | GB |
In late 1998, UCAC data were used to tie the Hubble Deep Field South (HDF-S) to the ICRF (Hipparcos) system (Zacharias et al. 1998). The UCAC data will provide a dense net of high accuracy star positions at a recent epoch to be used for proper motion determinations. It also contains a huge amount of double star
observations (separations 3").
The UCAC will assist the general astronomical community for a variety
of applications, including Schmidt plate reductions, galactic studies,
and minor planet observations. It will provide a reference
frame for large telescope observations from direct imaging to fiber
spectroscopy, to identify objects and to map out geometrical distortions
of instruments.
The UCAC1 catalog gives a first glimpse of the future final version.
The UCAC data will be required for an input catalog of the FAME space
mission and is likely to support other future space missions like SIM.
Gauss, F. S., Zacharias, N., Rafferty, T. J., Germain, M. E., Holdenried, E. R., Pohlman, J. W., & Zacharias, M. I. 1996, BAAS 28, 1282
Zacharias, N., Germain, M. E., & Rafferty, T. J. 1997, in: Proceedings Hipparcos Venice 97 (ESA publication SP-402), 177
Zacharias, N., Corbin, T. E., Zacharias, M. I., Rafferty, T. J., Seidelmann, P. K., & Gauss, F. S. 1998, BAAS, 30, 1367
Zacharias, N. & Zacharias, M. I. 1999, in ASP Conf. Ser., Vol. 172, Astronomical Data Analysis Software and Systems VIII, ed. D. M. Mehringer, R. L. Plante, & D. A. Roberts (San Francisco: ASP), 345