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(The bold columns are indexed columns)
Column NameDescriptionDatatype
btmagTycho-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
ccdmCCDM 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(n)
corrcorrelation (RAdeg,DEdeg)REAL
dedegObserved Tycho-2 Declination, ICRSDOUBLE
demdegMean 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_btmags.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_dedegs.e. of observed Tycho-2 Dec; note: The errors are based on error models.REAL
e_demdegs.e. of Dec at mean epoch; note: The errors are based on error models.SMALLINT
e_pmdes.e. of proper motion in Dec; note: The errors are based on error models.REAL
e_pmras.e. prop mot in RA*cos(dec); note: The errors are based on error models.REAL
e_radegs.e.RA*cos(dec), of observed Tycho-2 RA; note: The errors are based on error models.REAL
e_ramdegs.e. RA*cos(dec),at mean epoch; note: The errors are based on error models.SMALLINT
e_vtmags.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
elatEcliptic LatitudeDOUBLE
elonEcliptic LongitudeDOUBLE
epde_1990epoch-1990 of DEdegREAL
epdemmean epoch of Dec; note: The mean epochs are given in Julian years.REAL
epra_1990epoch-1990 of RAdegREAL
eprammean epoch of RA; note: The mean epochs are given in Julian years.REAL
glatGalactic LatitudeDOUBLE
glonGalactic LongitudeDOUBLE
hipHipparcos numberSMALLINT
nest4096HEALPIX index (Nsides 4096, Nest schem => ~52 arcsec sizeINTEGER
numNumber of positions usedSMALLINT
pflagmean 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
pmdeProper 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
pmraProper 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
posflgtype 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
proxproximity 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_demdegGoodness 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_pmdeGoodness 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_pmraGoodness 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_ramdegGoodness 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
radegObserved Tycho-2 Right Ascension, ICRSDOUBLE
ramdegMean 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_idRandom ID in the range 0.0 => 100.0REAL
ring256HEALPIX index (Nsides 256 => ~14 arcmin size)INTEGER
tycTycho-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
tyc1TYC 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
tyc2TYC2 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
tyc3TYC3 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
vtmagTycho-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