The Tycho-2 Catalogue:
Format Description

File Summary:

File Name Lrecl Records Explanations
catalog.dat 206 2539913 The Tycho-2 main catalogue
suppl_1.dat 122 17588 The Tycho-2 supplement-1
suppl_2.dat 122 1146 The Tycho-2 supplement-2
index.dat 42 9538 Index to Tycho-2 and supplement-1

Records are terminated with \r\n (CR,LF), making the physical record lengths two characters longer.

In the data files, the fields in each record are separated by a vertical bar, |. In this connection the TYC identifier (TYC1, TYC2 and TYC3) constitutes one field and the pair of a HIP number with a CCDM identifier is also considered one field. In the format descriptions, the vertical bars are indicated as "1X". If a numerical field may be blank, this is indicated by a question mark following the range specification in the Explanations column, e.g. "[ ]?".

Byte-by-byte description of file: catalog.dat

BytesFormat Units Label Explanations
1- 4 I4.4 --- TYC1 [1,9537]+= TYC1 from TYC or GSC (1)
6- 10 I5.5 --- TYC2 [1,12121] TYC2 from TYC or GSC (1)
12- 13 I1,1X --- TYC3 [1,3] TYC3 from TYC (1)
14- 15 A1,1X --- pflag [ PX] mean position flag (2)
16- 28 F12.8,1X deg mRAdeg []? Mean Right Asc, ICRS, epoch J2000 (3)
29- 41 F12.8,1X deg mDEdeg []? Mean Decl, ICRS, at epoch J2000 (3)
42- 49 F7.1,1X mas/yr pmRA* [-4418.0,6544.2]? prop. mot. in RA*cos(dec)
50- 57 F7.1,1X mas/yr pmDE [-5774.3,10277.3]? prop. mot. in Dec
58- 61 I3,1X mas e_mRA* [3,183]? s.e. RA*cos(dec),at mean epoch (5)
62- 65 I3,1X mas e_mDE [1,184]? s.e. of Dec at mean epoch (5)
66- 70 F4.1,1X mas/yr e_pmRA* [0.2,11.5]? s.e. prop mot in RA*cos(dec)(5)
71- 75 F4.1,1X mas/yr e_pmDE [0.2,10.3]? s.e. of proper motion in Dec(5)
76- 83 F7.2,1X yr mepRA [1915.95,1992.53]? mean epoch of RA (4)
84- 91 F7.2,1X yr mepDE [1911.94,1992.01]? mean epoch of Dec (4)
92- 94 I2,1X --- Num [2,36]? Number of positions used
95- 98 F3.1,1X --- g_mRA [0.0,9.9]? Goodness of fit for mean RA (6)
99-102 F3.1,1X --- g_mDE [0.0,9.9]? Goodness of fit for mean Dec (6)
103-106 F3.1,1X --- g_pmRA [0.0,9.9]? Goodness of fit for pmRA (6)
107-110 F3.1,1X --- g_pmDE [0.0,9.9]? Goodness of fit for pmDE (6)
111-117 F6.3,1X mag BT [2.183,16.581]? Tycho-2 BT magnitude (7)
118-123 F5.3,1X mag e_BT [0.014,1.977]? s.e. of BT (7)
124-130 F6.3,1X mag VT [1.905,15.193]? Tycho-2 VT magnitude (7)
131-136 F5.3,1X mag e_VT [0.009,1.468]? s.e. of VT (7)
137-140 I3,1X --- prox [3,999] proximity indicator (8)
141-142 A1,1X --- TYC [ T] Tycho-1 star (9)
143-148 I6 --- HIP [1,120404]? Hipparcos number
149-152 A3,1X --- CCDM CCDM component identifier for HIP stars(10)
153-165 F12.8,1X deg RAdeg Observed Tycho-2 Right Ascension, ICRS
166-178 F12.8,1X deg DEdeg Observed Tycho-2 Declination, ICRS
179-183 F4.2,1X yr epRA [0.81,2.13] epoch-1990 of RAdeg
184-188 F4.2,1X yr epDE [0.72,2.36] epoch-1990 of DEdeg
189-194 F5.1,1X mas e_RA* s.e.RA*cos(dec), of observed Tycho-2 RA (5)
195-200 F5.1,1X mas e_DE s.e. of observed Tycho-2 Dec (5)
201-202 A1,1X --- posflg [ DP] type of Tycho-2 solution (11)
203-206 F4.1 --- corr correlation (RAdeg,DEdeg)

Byte-by-byte description of the files: suppl_1.dat and suppl_2.dat

Bytes Format Units Label Explanations
1- 4 I4.4 --- TYC1 [2,9529]+= TYC1 from TYC (1)
6- 10 I5.5 --- TYC2 [1,12112] TYC2 from TYC (1)
12- 13 I1,1X --- TYC3 [1,4] TYC3 from TYC (1)
14- 15 A1,1X --- flag [HT] data from Hipparcos or Tycho-1 (2)
16- 28 F12.8,1X deg RAdeg Right Asc, ICRS, at epoch J1991.25
29- 41 F12.8,1X deg DEdeg Decl, ICRS, at epoch J1991.25
42- 49 F7.1,1X mas/yr pmRA* []? prop. mot. in RA*cos(dec)
50- 57 F7.1,1X mas/yr pmDE []? prop. mot. in Dec
58- 63 F5.1,1X mas e_RA* s.e. RA*cos(dec)
64- 69 F5.1,1X mas e_DE s.e. of Dec
70- 75 F5.1,1X mas/yr e_pmRA* []? s.e. prop mot in RA * cos(dec)
76- 81 F5.1,1X mas/yr e_pmDE []? s.e. of proper motion in Dec
82- 83 A1,1X --- mflag [ BVH] (3)
84- 90 F6.3,1X mag BT []? Tycho-1 BT magnitude (4)
91- 96 F5.3,1X mag e_BT []? s.e. of BT (4)
97-103 F6.3,1X mag VT []? Tycho-1 VT or Hp magnitude (4)
104-109 F5.3,1X mag e_VT []? s.e. of VT (4)
110-113 I3,1X --- prox [1,999] proximity indicator (5)
114-115 A1,1X --- TYC [ T] Tycho-1 star
116-121 I6 --- HIP [1,120404]? Hipparcos number
122-122 A1 --- CCDM CCDM component identifier for HIP stars

Byte-by-byte description of file: index.dat

Bytes Format Units Label Explanations
1- 8 I7,1X --- rec_t2 + Tycho-2 rec. of 1st star in region (1)
9-15 I6,1X --- rec_s2 += Suppl-1 rec. of 1st star in region (1)
16-22 F6.2,1X deg RAmin [-0.01,] smallest RA in region (2)
23-29 F6.2,1X deg RAmax [,360.00] largest RA in region (2)
30-36 F6.2,1X deg DEmin smallest Dec in this region (2)
37-42 F6.2 deg DEmax largest Dec in this region (2)


[Tycho 2 Catalog]