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A license friendly NGC/IC objects database

Credits: Mattia Verga

DOI: 10.21938/y.1ejWUD_MQ6b_eDFoVbbw


OpenNGC is a database containing positions and main data of NGC (New General Catalogue) and IC (Index Catalogue) objects. Unlike other similar databases which are released with license limitations, OpenNGC is released under CC-BY-SA-4.0 license, which allows the use for a wider range of cases.

For information about data fields contained in the database, please see the file NGC_guide.txt.


OpenNGC has been built by merging data from:

Some common names are taken from internet sources like Wikipedia.


See the sources column for a detailed description of where each object data has been taken from.

  • Coordinates are usually taken from NED; some multiple objects, like multiple galaxies, are also listed following NED schema, thus the NED suffix.

  • B-Mag and V-Mag have different sources: for galaxies they're usually originated from LEDA if available, otherwise are from SIMBAD. J, H and K magnitudes are always from SIMBAD.

  • Parallax, proper motions, radial velocity and redshift are referred to the main value reported from SIMBAD.

  • Galaxies (G | GGroup | GPair | Gtrpl): data about major axis, minor axis, position angle, surface brightness and Hubble classification is taken from LEDA; if major axis or minor axis data is not available from LEDA, then it's taken from SIMBAD (usually from 2MASS measures, so they're referred to IR, not visual).

  • Star clusters (OCl | GCl | *Ass | Cl+N): where available, diameters and position angle are taken from the following HEASARC tables: mwsc [central_radius]; smcclustrs [major_diameter, minor_diameter, position_angle]; lmcextobj [major_axis, minor_axis, position_angle].

  • Planetary Nebulae (PN): data is imported from HEASARC plnebulae table, fields used are opt_diameter, umag_cstar, bmag_cstar, vmag_cstar, name, pk_name, iras_name, alt_name_1, alt_name_2, alt_name_3, alt_name_4.

  • Nebulae (HII | Neb | EmN | RfN | SNR): where available, major and minor axis are taken from HEASARC lbn table [large_dimension], [small dimension].


The 'addendum' folder contains a separate catalog file with notably objects that are not part of the NGC or IC catalog. These objects may be of some interest to amateur astronomers.

Note that two Messier objects (M40 and M45) haven't got any NGC or IC designation, so they're listed only in the addendum.


For a basic Python interface to OpenNGC data, see PyOngc project at


A TAP-accessible database table of OpenNGC is available on