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Table: tycho2.main
(The bold columns are indexed columns)
| Column Name | Description | Datatype |
|---|---|---|
| btmag | Tycho-2 BT magnitude; note: Blank when no magnitude is available. Either BTmag or VTmag is always given. Approximate Johnson photometry may be obtained as: V = VT -0.090*(BT-VT) B-V = 0.850*(BT-VT) Consult Sect 1.3 of Vol 1 of "The Hipparcos and Tycho Catalogues", ESA SP-1200, 1997, for details. | REAL |
| ccdm | CCDM component identifier for HIP stars; note: The CCDM component identifiers for double or multiple Hipparcos stars contributing to this Tycho-2 entry. For photocentre solutions, all components within 0.8 arcsec contribute. For double star solutions any unresolved component within 0.8 arcsec contributes. For single star solutions, the predicted signal from close stars were normally subtracted in the analysis of the photon counts and such stars therefore do not contribute to the solution. The components are given in lexical order. | VARCHAR |
| corr | correlation (RAdeg,DEdeg) | REAL |
| dedeg | Observed Tycho-2 Declination, ICRS | DOUBLE |
| demdeg | Mean Decl, ICRS, at epoch=J2000; note: The mean position is a weighted mean for the catalogues contributing to the proper motion determination. This mean has then been brought to epoch 2000.0 by the computed proper motion. See Note(2) above for details. Tycho-2 is one of the several catalogues used to determine the mean position and proper motion. The observed Tycho-2 position is given in the fields RAdeg and DEdeg. | DOUBLE |
| e_btmag | s.e. of BT; note: Blank when no magnitude is available. Either BTmag or VTmag is always given. Approximate Johnson photometry may be obtained as: V = VT -0.090*(BT-VT) B-V = 0.850*(BT-VT) Consult Sect 1.3 of Vol 1 of "The Hipparcos and Tycho Catalogues", ESA SP-1200, 1997, for details. | REAL |
| e_dedeg | s.e. of observed Tycho-2 Dec; note: The errors are based on error models. | REAL |
| e_demdeg | s.e. of Dec at mean epoch; note: The errors are based on error models. | SMALLINT |
| e_pmde | s.e. of proper motion in Dec; note: The errors are based on error models. | REAL |
| e_pmra | s.e. prop mot in RA*cos(dec); note: The errors are based on error models. | REAL |
| e_radeg | s.e.RA*cos(dec), of observed Tycho-2 RA; note: The errors are based on error models. | REAL |
| e_ramdeg | s.e. RA*cos(dec),at mean epoch; note: The errors are based on error models. | SMALLINT |
| e_vtmag | s.e. of VT; note: Blank when no magnitude is available. Either BTmag or VTmag is always given. Approximate Johnson photometry may be obtained as: V = VT -0.090*(BT-VT) B-V = 0.850*(BT-VT) Consult Sect 1.3 of Vol 1 of "The Hipparcos and Tycho Catalogues", ESA SP-1200, 1997, for details. | REAL |
| elat | Ecliptic Latitude | DOUBLE |
| elon | Ecliptic Longitude | DOUBLE |
| epde_1990 | epoch-1990 of DEdeg | REAL |
| epdem | mean epoch of Dec; note: The mean epochs are given in Julian years. | REAL |
| epra_1990 | epoch-1990 of RAdeg | REAL |
| epram | mean epoch of RA; note: The mean epochs are given in Julian years. | REAL |
| glat | Galactic Latitude | DOUBLE |
| glon | Galactic Longitude | DOUBLE |
| hip | Hipparcos number | SMALLINT |
| nest4096 | HEALPIX index (Nsides 4096, Nest schem => ~52 arcsec size | INTEGER |
| num | Number of positions used | SMALLINT |
| pflag | mean position flag; note: = normal mean position and proper motion. P = the mean position, proper motion, etc., refer to the photocentre of two Tycho-2 entries, where the BT magnitudes were used in weighting the positions. X = no mean position, no proper motion. | CHAR |
| pmde | Proper motion in Dec; note: Some Hipparcos stars (having a positive number in the HIP column) have no proper motions; these are virtually all in multiple systems. | REAL |
| pmra | Proper motion in RA*cos(dec); note: Some Hipparcos stars (having a positive number in the HIP column) have no proper motions; these are virtually all in multiple systems. | REAL |
| posflg | type of Tycho-2 solution; note: = normal treatment, close stars were subtracted when possible. D = double star treatment. Two stars were found. The companion is normally included as a separate Tycho-2 entry, but may have been rejected. P = photocentre treatment, close stars were not subtracted. This special treatment was applied to known or suspected doubles which were not successfully (or reliably) resolved in the Tycho-2 double star processing. | CHAR |
| prox | proximity indicator; note: Distance in units of 100 mas to the nearest entry in the Tycho-2 main catalogue or supplement. The distance is computed for the epoch 1991.25. A value of 999 (i.e. 99.9 arcsec) is given if the distance exceeds 99.9 arcsec. | SMALLINT |
| q_demdeg | Goodness of fit for mean Dec; note: This goodness of fit is the ratio of the scatter-based and the model-based error. It is only defined when Num > 2. Values exceeding 9.9 are truncated to 9.9. | REAL |
| q_pmde | Goodness of fit for pmDE; note: This goodness of fit is the ratio of the scatter-based and the model-based error. It is only defined when Num > 2. Values exceeding 9.9 are truncated to 9.9. | REAL |
| q_pmra | Goodness of fit for pmRA; note: This goodness of fit is the ratio of the scatter-based and the model-based error. It is only defined when Num > 2. Values exceeding 9.9 are truncated to 9.9. | REAL |
| q_ramdeg | Goodness of fit for mean RA; note: This goodness of fit is the ratio of the scatter-based and the model-based error. It is only defined when Num > 2. Values exceeding 9.9 are truncated to 9.9. | REAL |
| radeg | Observed Tycho-2 Right Ascension, ICRS | DOUBLE |
| ramdeg | Mean Right Asc, ICRS, epoch=J2000; note: The mean position is a weighted mean for the catalogues contributing to the proper motion determination. This mean has then been brought to epoch 2000.0 by the computed proper motion. See Note(2) above for details. Tycho-2 is one of the several catalogues used to determine the mean position and proper motion. The observed Tycho-2 position is given in the fields RAdeg and DEdeg. | DOUBLE |
| random_id | Random ID in the range 0.0 => 100.0 | REAL |
| ring256 | HEALPIX index (Nsides 256 => ~14 arcmin size) | INTEGER |
| tyc | Tycho-1 star; note: = no Tycho-1 star was found within 0.8 arcsec (quality 1-8) or 2.4 arcsec (quality 9). T = this is a Tycho-1 star. The Tycho-1 identifier is given in the beginning of the record. For Tycho-1 stars, resolved in Tycho-2 as a close pair, both components are flagged as a Tycho-1 star and the Tycho-1 TYC3 is assigned to the brightest (VT) component. The HIP-only stars given in Tycho-1 are not flagged as Tycho-1 stars. | SMALLINT |
| tyc1 | TYC from TYC or GSC; note: The TYC identifier is constructed from the GSC region number (TYC1), the running number within the region (TYC2) and a component identifier (TYC3) which is normally 1. Some non-GSC running numbers were constructed for the first Tycho Catalogue and for Tycho-2. The recommended star designation contains a hyphen between the TYC numbers, e.g. TYC 1-13-1. | SMALLINT |
| tyc2 | TYC2 from TYC or GSC; note: The TYC identifier is constructed from the GSC region number (TYC1), the running number within the region (TYC2) and a component identifier (TYC3) which is normally 1. Some non-GSC running numbers were constructed for the first Tycho Catalogue and for Tycho-2. The recommended star designation contains a hyphen between the TYC numbers, e.g. TYC 1-13-1. | SMALLINT |
| tyc3 | TYC3 from TYC; note: The TYC identifier is constructed from the GSC region number (TYC1), the running number within the region (TYC2) and a component identifier (TYC3) which is normally 1. Some non-GSC running numbers were constructed for the first Tycho Catalogue and for Tycho-2. The recommended star designation contains a hyphen between the TYC numbers, e.g. TYC 1-13-1. | SMALLINT |
| vtmag | Tycho-2 VT magnitude; note: Blank when no magnitude is available. Either BTmag or VTmag is always given. Approximate Johnson photometry may be obtained as: V = VT -0.090*(BT-VT) B-V = 0.850*(BT-VT) Consult Sect 1.3 of Vol 1 of "The Hipparcos and Tycho Catalogues", ESA SP-1200, 1997, for details. | REAL |
