GSC II Properties

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Last Updated Jan 2001

Copyright © 2001 The Association of Universities for Research in Astronomy, Inc. All Rights Reserved.

Catalog Properties

Quick Fact Sheet on GSC 2.2 vs. GSC 1.1

GSC 1.1
GSC 2.2
Total Objects
18,819,291
435,457,355
Mean epoch of catalog positions
1981.8
1992.2
Magnitude limit
15.5
18.5 F, 19.5 J
Complete to magnitude limit
No
Yes*
Bandpass: North
V
F and J
Bandpass: South
J**
F and J**
Digitization resolution
1.7 arcsec
1 arcsec***
Source for bright stars
Hipparchos Input Catalog
Tycho 2
Astrometry:
Reference frame
FK4
ICRF

Reference catalogs

AGK3, SAO: 10^2 calibrators per plate

ACT, Tycho2: 10^3 calibrators per plate

Projection
Gnomonic
Equidistant

Systematic error correction
None
mask, refraction precorrection
Errors
0.5" - 1.2"
errors increase near plate edges
0.3" - 0.75"
errors increase near plate edges for F > 16
Photometry:

Reference catalogs
GSPC1: 6 calibrators per plate
GSPC2: 10^2 calibrators per plate
Errors
0.5 mag
0.2 - 0.25 mag

* Except for the most difficult areas such as around bright stars, globular clusters, etc

** 93 short exposure V plates replace the deep J plates in the galactic plane

*** Approximately half the southern J plates are included at the original 1.7" resolution

Quick Fact Sheet on GSC 2.2

Total Number of Objects:
435,457,355
Number of Objects in the North:
165,405,323 (38%)
Number of Objects in the South:
270,052,032 (62%)
Number of Stars:
170,095,789 (39%)
Number of Non-Stars:
265,361,566 (61%)