vira_tycho2

Convert Tycho2 .dat files to QSC file

Synopsis

vira_tycho2 [OPTIONS] INPUT_GLOB [INPUT_GLOB ...]

Description

vira_tycho2 is a command-line utility for converting Tycho-2 star catalog data files (.dat format) into a single Quipu Star Catalog (QSC) file. The Tycho-2 catalog is one of the most comprehensive and accurate star catalogs available, containing astrometric and photometric data for over 2.5 million stars.

This tool processes multiple Tycho-2 data files (typically named tyc2.dat.XX where XX is a sequence number) and combines them into a unified, optimized QSC format suitable for astronomical visualization and simulation applications.

Arguments

INPUT_GLOB [INPUT_GLOB …]

One or more glob patterns specifying the Tycho-2 .dat files to process. Common patterns include tyc2.dat.*, *.dat, or explicit file lists.

Options

-o, –output DIRECTORY

Directory where the output tycho2.qsc file will be written (default: current directory .).

–help

Display help information and exit.

–version

Display version information and exit.

Input Data Format

The tool expects Tycho-2 catalog files in the standard .dat format as distributed by astronomical data centers. These files typically contain:

  • Star positions (Right Ascension, Declination)

  • Proper motions

  • Photometric data (magnitudes in multiple bands)

  • Astrometric quality indicators

  • Cross-reference identifiers

Common file naming patterns: - tyc2.dat.00, tyc2.dat.01, …, tyc2.dat.19 (official distribution) - tycho2_*.dat (alternative naming)

Output

The tool generates a single tycho2.qsc file containing:

  • Complete merged star catalog data

  • Stars sorted by magnitude (brightest first)

  • Optimized binary format for fast access

  • Preserved astrometric and photometric precision

The output file is named tycho2.qsc and will be placed in the specified output directory.

Examples

Convert all Tycho-2 files in current directory:

vira_tycho2 tyc2.dat.*

References