Tycho-2 TDSC Merge

Tycho-2 merged with the TDSC catalog and TDSC supplement.The Tycho Double Star Catalogue, (TDSC, ) contains 98482 components of double and multiple systems processed in the Tycho-2 context. It includes either original Tycho-2 data or results from a dedicated re-processing aimed at binaries. As pointed out by P. Marrese (personal communication), the TDSC star with identifier 29583 is redundant and it was therefore skipped. The TDSC supplement contains data from an additional 4777 components from either Hipparcos or Tycho-1.The Tycho-2 main catalogue  contains 2539913 sources, including many binaries, but a minimum separation of 0.8 arcsec was imposed during the catalogue construction. The Tycho-2 supplement-1 contains data for 17588 Hipparcos and Tycho-1 stars, which do not appear in the main catalogue, but only the 4777 stars relevant for TDSC are included here. The Tycho-2 supplement-2 contains an additional 1146 Tycho-1 stars of poor quality.We have merged Tycho-2 (main) with the TDSC main and supplement, keeping the Tycho-2 data model and extending it to include TDSC–specific fields. This is only possible to a certain degree as specified in detail below. In particular, Tycho-2 includes fields for mean position, proper motion etc. for a combination of Tycho-2 and several ground based catalogues. These fields are inherited for TDSC main stars, but were not derived for the TDSC supplement, where we only provide HIP proper motions. For Tycho-2 stars not in TDSC, blank TDSC fields were appended.For Tycho-2 stars in TDSC, the following fields were replaced by the corresponding TDSC fields:

tyc1, tyc2, tyc3;
hip;
ccdm.

In addition, if the TDSC contains a new solution:

btMag, eBtMag, vtMag, eVtMag, raDeg, deDeg, epRa1990, epDe1990, eRaDeg, eDeDec;
The mean position flag, pflag, is set to ‘P’ (“photocentre") if resolved and there are Tycho-2 mean positions. Mean position etc. are then repeated for both new components;
The proximity indicator, prox, is set to blank if the Tycho-2 star was resolved in TDSC;
The type-of-solution flag, posflg, set to ‘N’;
For resolved Tycho-2 stars, two records are given.

For the few TDSC stars with new solutions, but not in Tycho-2, and for the TDSC supplement stars (Hipparcos or Tycho-1), the Tycho-2 part of the merged record was populated in the following way:

TYC1..3 from TDSC;
pflag set to TDSC pmflg (‘H’ or ‘X’), ‘H’ indicating Hip proper motions;
no mean position and related fields;
proper motions only for Hipparcos stars;
B_T, V_T photometry from TDSC;
Tycho-1 flag, tyc, is set to posflg, i.e. ‘T’ or ‘H’ although Hipparcos stars may well be in Tycho-1;
Hipparcos, hip, and CCDM, ccdm, identifiers from TDSC;
astrometry from TDSC, but the (ra, dec)-correlation, corr, is set to blank.

New TDSC specific fields added after the Tycho-2 part of the record:

sysNo, cmp, nMain, nSup, magflg, wds, note, hd;
rcmp, pa, sep, ePa, ePaSep, eSep.