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;
- $B_{\rm T}, V_{\rm T}$ 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.

本数据集为第谷2星表（Tycho-2）与双星第谷星表（Tycho Double Star Catalogue, TDSC）及其补充表的合并产物。
TDSC共收录98482个双星及多星系统的成员天体，其处理基于第谷2星表的语境框架，数据来源既包含原始第谷2星表数据，也涵盖针对双星系统开展的专属再处理结果。正如P. Marrese（私人通信）所指出的，标识符为29583的TDSC天体存在冗余，因此已被剔除。
TDSC补充表收录了源自依巴谷（Hipparcos）或第谷1星表（Tycho-1）的额外4777个天体数据。
第谷2主星表总计包含2539913个天体源，其中包含大量双星系统，但在星表构建阶段设定了0.8角秒的最小角距阈值。第谷2补充表-1收录了17588颗未出现在主星表中的依巴谷与第谷1星表天体，但本合并数据集仅纳入其中与TDSC相关的4777颗天体。第谷2补充表-2则包含1146颗质量较差的第谷1星表天体。
本次合并保留了第谷2星表的数据模型，并扩展加入了TDSC专属字段，但合并操作存在一定限制，具体细节如下文所述。具体而言，第谷2星表包含针对第谷2数据与多套地面观测星表组合得到的平均位置、自行等字段，这些字段会被TDSC主星表天体继承，但TDSC补充表并未推导此类字段，仅提供依巴谷自行数据。对于未出现在TDSC中的第谷2星表天体，我们为其追加了空白的TDSC专属字段。
对于出现在TDSC中的第谷2星表天体，以下字段将被对应的TDSC字段替换：
- tyc1、tyc2、tyc3；
- hip；
- ccdm。
此外，若TDSC包含新的解算结果，则：
- btMag、eBtMag、vtMag、eVtMag、raDeg、deDeg、epRa1990、epDe1990、eRaDeg、eDeDec；
- 若天体在TDSC中被分解且存在第谷2平均位置，则平均位置标记pflag将被设为'P'（'光心'），随后将为两个新成员天体重复输出平均位置等信息；
- 若第谷2星表天体在TDSC中被分解，则邻近指示符prox将被设为空白；
- 解类型标记posflg将被设为'N'；
- 对于被分解的第谷2星表天体，将生成两条记录。
对于少量拥有新解算结果但未出现在第谷2星表中的TDSC天体，以及TDSC补充表天体（依巴谷或第谷1星表天体），合并记录中的第谷2部分将按如下规则填充：
- TYC1至TYC3字段取自TDSC；
- pflag将被设为TDSC的pmflg（'H'或'X'），其中'H'代表依巴谷自行；
- 不包含平均位置及相关字段；
- 仅依巴谷天体拥有自行数据；
- $B_{\rm T}$、$V_{\rm T}$测光数据取自TDSC；
- 第谷1标记tyc将被设为posflg，即'T'或'H'，尽管依巴谷天体大概率也存在于第谷1星表中；
- 依巴谷编号hip与CCDM编号ccdm取自TDSC；
- 天体测量数据取自TDSC，但（赤经、赤纬）相关性corr将被设为空白。
在合并记录的第谷2部分之后，将追加以下TDSC专属字段：
- sysNo、cmp、nMain、nSup、magflg、wds、note、hd；
- rcmp、pa、sep、ePa、ePaSep、eSep。

搜集汇总

背景与挑战

背景概述

Tycho-2 TDSC Merge数据集是Tycho-2主目录与TDSC目录及其补充数据的合并，包含2561886行数据和53个字段，详细记录了双星和多星系统的位置、运动、光度等信息。该数据集特别处理了TDSC特有的字段，并保留了Tycho-2的数据模型，适用于天文学研究中的双星系统分析。