blend_stars

giant.catalogues.giant_catalogue:

giant.catalogues.giant_catalogue.blend_stars(groups, database_connection, limiting_mag, ref_mag=4)[source]

Blends groups of stars together into a single “apparent” star as viewed by a camera.

Star magnitude, right ascension, declination, and proper motion are all blended in the final product. The blending is based off of an internal memo by Sean Semper.

The groups input should provide 2 columns, the first column “a” should provide the primary (brightest) star in each group. The second column “b” should provide a set of all of the stars that are to be blended to each other an “a”. This is what is returned by find_star_pairs(). This function uses the database to retrieve the individual star records for memory purposes.

The blended star is given an id that is the negative of the brightest star in the group. The blended stars are returned as a pandas dataframe.

Typically this is not used directly by the user. Instead se build_catalogue() or script scripts.build_catalogue.

Parameters:

  • groups (DataFrame) – The dataframe specifying the groups to blend

  • database_connection (Connection) – The connection to the sqlite3 database to retrieve the stars from

  • limiting_mag (Real) – The limiting magnitude that blended stars must achieve for them to be included

  • ref_mag (Real) – The reference magnitude to use when blending the stars

Returns:

The dataframe of the blended apparent stars

Return type:

DataFrame