Table information for 'ucac3.main'

General

Table Description: The UCAC3 all-sky CCD astrograph catalogue, minus the fields from 2MASS and SuperCosmos and matching/object flags (which can be recovered with a local crossmatch).

This table is available for ADQL queries and through the TAP endpoint.

Resource Description: The Third US Naval Observatory CCD Astrograph catalogue (UCAC3) is an all-sky catalgoue containing just over 100 million objects covering about R = 8-16 mag. This table contains the original data content of UCAC3 but leaves out the data objetained by crossmatching to other catalogs.

For a list of all services and tables belonging to this table's resource, see Information on resource 'UCAC3 nocross'

Citing this table

@MISC{vo:ucac3_main,
  year=2009,
  title={{UCAC3} nocross},
  author={{GAVO} Data Center},
  url={http://dc.zah.uni-heidelberg.de/tableinfo/ucac3.main},
  howpublished={{VO} resource provided by the {GAVO} Data Center}
}

Columns

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Columns that are parts of indices are marked like this.

VOResource

VO nerds may sometimes need VOResource XML for this table.

Notes

• Note 1

  Positions are on the International Celestial Reference System (ICRS) as represented by the Hipparcos / Tycho-2 catalogs. The epoch for the positions of all stars is J2000.0; the weighted mean catalog position was updated using the provided proper motions. The observational UCAC position is but one of several going into these values and is not given in the UCAC3, thus the original UCAC observation cannot be recovered from these data.

• Note 2

  Systematic errors are expected to be below 0.1 mag for im1, im2 photometric results obtained from the UCAC CCD pixel data. The aperture photometry is considered more robust, particularly for "odd" cases, while the model fit magnitude is expected to be more accurate for "well behaved" stars.

• Note 3

  For many stars a photometric error based on the scatter from individual observations of that star on different CCD frames could be obtained. A model error was also attempted to be assigned, based on the S/N ratio. The error quoted here is the larger of the 2. If that error exceeds 0.9 mag the error was set to 0.9 mag.

• Note 4

  The object type flag is used to identify possible problems with a star and has the following meaning:

  S	warning: object could be from possible streak
  N	warning: object is near overexposed star
  blank	good star
  c	good star (data copied from another entry)
  o	warning: contains at least 1 overexposed image
  O	warning: all images are overexposed or "bad"

• Note 5

  The dsf flag is a double star flag used to indicate the type/quality of double star fit with the following meaning:

  0	single star
  1	primary of pair with unreal secondary = single
  2	forced separation, on same frame
  3	blended image, some CCD frames show single star, some double
  4	forced separation, 2 objects on same frame number
  5	primary component of real double
  6	secondary component of real double
  7	other "odd" case

• Note 6

  A zero for the number of used images indicates that all images have some "problem" (such as overexposure). In that case an unweighted mean over all available images (na) is taken to derive the mean position, while normally a weighted mean was calculated based on the "good" images, excluding possible problem images (nu <= na).