The second Tycho Input Catalogue TIC2 ====================================================================== This file presents the format and contents of the second Tycho Input Catalogue, TIC2. This catalogue, which has been used during the processing and construction of the Tycho-2 Catalogue, contains 4,351,323 stars and is aimed to be as complete as possible to a limiting magnitude T = 12.5 mag (with the T band defined as the sum of the Tycho BT and VT bands). Format description: the original data file is binary, in big-endian format, and contains 4,351,323 records. Each record contains 64 bytes. All integers are signed. During ingestion on the TAP server, the fields TIC2ID, TIC2, RAdeg, and DEdeg have been added. ----------------------------------------------------------------------------------------------------- Name Offset Type Units Description ----------------------------------------------------------------------------------------------------- TIC2ID The running number [1,4351323] in the Second Tycho Input Catalogue (TIC2) TIC2 TYC2_1-3 (TIC2 identifier) TIC2_1 0 I*2 TYC or GSC region number (Note 1) TIC2_2 2 I*2 TYC or GSC running number within the region TIC2_3 4 I*2 TYC or GSC component number Ep-1900 6 I*2 0.01 yr Epoch of position minus 1900 (Note 2) RAmas 8 I*4 1 mas Right ascension (Note 3) DEmas 12 I*4 1 mas Declination (Note 3) RAdeg deg Right ascension (Note 3) DEdeg deg Declination (Note 3) Plx 16 I*2 1 mas Parallax (from the Hipparcos Catalogue, main or DMSA/C) pmRA 18 I*2 1 mas/yr Proper motion in right ascension multiplied with cos(declination) pmDE 20 I*2 1 mas/yr Proper motion in declination e_pos 22 I*2 0.01 arcsec Error in sky position xN18 24 I*4 1E-9 rad x coordinate of unit vector in N18 system (Note 3)(Note 4) yN18 28 I*4 1E-9 rad y coordinate of unit vector in N18 system (Note 3)(Note 4) zN18 32 I*4 1E-9 rad z coordinate of unit vector in N18 system (Note 3)(Note 4) dxN18 36 I*4 1E-9 rad/yr Time derivative of x (Note 4) dyN18 40 I*4 1E-9 rad/yr Time derivative of y (Note 4) dzN18 44 I*4 1E-9 rad/yr Time derivative of z (Note 4) BTmag 48 I*2 0.001 mag B_T magnitude e_BTmag 50 I*2 0.001 mag B_T magnitude error VTmag 52 I*2 0.001 mag V_T magnitude e_VTmag 54 I*2 0.001 mag V_T magnitude error TYCrecno 56 I*4 Record number in TYC file (or 0) Flags 60 I*4 31 flag bits (Note 5) ----------------------------------------------------------------------------------------------------- Note 1: The stars in TIC2 are sorted according to a region number from 1 to 105278 (declination -90 ... +90 deg) following the description in Volume 4, Chapter 4 of "The Hipparcos and Tycho Catalogues" (ESA 1997). Note 2: The Epoch is 1991.25 if proper motions are available. Note 3: The position coordinates (x,y,z) are given in the N18 reference system (a preliminary NDAC reference system derived from 18 months of observations), but RA and DE are in the Hipparcos system. The prediction software used attitude data given in N18. A Hipparcos star should therefore transit at the predicted time when the input position is also in N18. Note 4: 1E-9 rad is roughly 0.2 mas. Note 5: The Flags field contains a 31-bit flag with the following coding: F00 : Zero (most significant bit); F01 : HIP star; F02 : HIP reference star (single, H2 = blank); F03 : Recommended reference star in TYC; F04 : Photometric reference star (subset of TYC; Note 6); F05 : TYC unresolved double: T49 = ['D','R','S']; F06 : TYC variability flags: T48 = ['U','V'] or T47 set; F07 : High proper motion star (proper motion > 100 mas/yr); F08 : Monitor star (not set); F09 : Zero if suited for parasite rejection (see Tycho-2 sorted counts); F10-F11: TIC2 proximity: 0: >10 arcsec, 1: 3-10 arcsec, 2: 1-3 arcsec, 3: < 1 arcsec; F12-F13: GSC1.2 classification: 0: star, 1: galaxy, 2: blend, 3: non-star; F14-F15: GSC1.2 classification quality: 0: guess, 1: possible, 2: probable, 3: sure; F16-F19: Source of position (Note 7); F20-F23: Source of proper motion (Note 7); F24-F27: Source of B_T magnitude (Note 7); F28-F31: Source of V_T magnitude (Note 7). Note 6: The 520,631 photometric reference stars are TYC stars defined in the description of fields T34-35, i.e., not suspected of photometric variability. Eight sets of stars are included non-redundantly, according to this priority order: Set no. 1: All HIP and DMSA/C astrometric entries with Hp<12.5 (128,412 entries); Set no. 2: All TYC (934,901 entries), updated with TYCAC proper motions (for 890,812 entries); Set no. 3: 116 bright PPM stars missing in TYC, cf. Volume 4, Table 17.1; Set no. 4: All Starnet with T<13.0 (2,616,761 entries); Set no. 5: GSC1.2 with T<12.5 (461,494 entries). Proper motion from USNO-A1.0 and GSC1.1 when possible. Note that the GSC plates are calibrated +/-0.2 mag to V_T for Palomar Quick-V plates in the northern sky and to T for UKST-J plates in the southern sky. The remaining photometric bands (B_T, V_T, T) are derived by means of the USNO-A1.0 colour index m_b-m_r. The B_T-V_T colour index will be obtained with a standard error of 0.6 mag by the formula B_T-V_T = 0.3 + 0.4 * (m_b-m_r). This low-precision approximation adds at most a standard error of 0.3 mag to the error of T derived from V_T for the Quick-V plates; Set no. 6: USNO-A1.0, m_b < 12 or m_r < 12 (489,958 entries). Note that m_b and m_r are adopted for, respectively, B_T and V_T; Set no. 7: Some 10,000 random spots on the sky to allow a reliability estimation the reduction software ; Set no. 8: Some 75,335 possible high proper motion stars. Note 7: Sources of position, proper motion, B_T magnitude, and V_T magnitude (see flags F16-F31 and Note 5): 0: HIP; 1: TYC; 2: PPM; 3: Starnet; 4: GSC1.2; 5: USNO-A1.0; 6: TYCAC; 7: GSC1.x and USNO-A1.0; 8: No data or random, empty spots on the sky; 9: High proper motion candidates (doubly redundant entries with boldly guessed proper motion); 10: ACT (added later for proper motions). Acknowledgements: access to preliminary versions of TYCAC, Starnet, and GSC1.2 from ARI and STScI has been indispensable for the construction of TIC2. ======================================================================