Note: Errors found in the Hipparcos catalogue are reported in the file errata.htx
Note that the errors on the
proper motions are large (∼50mas/yr), and therefore the positions
computed at an epoch different from 1991.25 have a large (∼0.4")
The Tycho Epoch Photometry data can
be accessed from the morePhoto column
(includes VT, BT and Hp photometric data for Hipparcos stars
contains 526,280,881 sources, and is based on a
re-reduction of the Precision Measuring Machine (PMM) scans
from POSS-I O and E plates (>=-18°) and SRC-J and
ESO-R plates (<=-20°).
USNO-A2.0 was created by Dave Monet (Flagstaff Station, U.S. Naval Observatory.
The major difference between USNO-A2.0 and its previous version
USNO-A1.0 is that A1.0 used the
Guide Star Catalog as its reference frame whereas
A2.0 uses the ICRF as realized by the
USNO ACT catalog (Urban et al. 1997).
The VizieR search engine uses an
on-line compressed version
(3.6Gbytes) which was generated at CDS.
Note: The Guide Star Catalog has been constructed to support the
operational need of the Hubble Space Telescope.
It contains over 25 million positions for about 19 million
objects, of which more than 15 million are classified as stars.
The version 1.2 is a new astrometric reduction which results in
absolute position errors about 0.3-0.4 arcsec.
(see GSC pages at URL http://www-gsss.stsci.edu/gsc/gsc.html)
Note: The GSC-ACT (or GSC1.3)
is a recalibration of the GSC1.1, the catalogue constructed
to support the operational need of the Hubble Space Telescope,
with the ACT, the combination of the Astrographic Catalogue
and the Tycho catalogue derived from the Hipparcos
mission; see http://www.projectpluto.com/gsc_act.htm for more details
about this recalibration.
Note: The current version includes only the North (POSS-I plates)
Note: Zone -40/+50deg
Note: UCAC5 document
(original column names in green) (1692919135 rows)
(original column names in green) (1811709771 rows)
Note: SDSS is also available from http://www.sdss.org/
Note: See also the ARICNS (Astronomische Rechen-Institut database for Nearby Stars); some errors can be found in notes.tex
Note: SDSS is also available from http://www.sdss3.org/dr9/