NGC Catalog
8373 objects in the NGC catalog
New General Catalogue
Author
John Louis Emil Dreyer (1852-1926)
Year
1888
Objects
7840
The New General Catalogue of Nebulae and Clusters of Stars (NGC) is an astronomical catalogue compiled by John Louis Emil Dreyer in 1888. It contains 7,840 deep-sky objects and is one of the most comprehensive catalogs of its kind. The NGC expanded upon previous catalogs and remains a fundamental reference for astronomers today.
Data Sources
- OpenNGC Database - Modern digitized version with corrections and updates
- Wikipedia - New General Catalogue - Historical background and detailed information
Objects are numbered NGC 1 through NGC 7840. Many objects have been reclassified or found to be duplicate entries since the original catalog was published.
Filter Objects
| Name | Type | RA | Dec | Mag | Constellation | Actions |
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About Deep Sky Data
Data Source
Deep sky object data comes from the OpenNGC database by Mattia Verga. Coordinates, magnitudes, and object classifications are sourced from authoritative astronomical catalogs including NGC, IC, Messier, and Caldwell. Source repository: OpenNGC database
Photometric Systems
V-band (Visual): Johnson V filter centered at ~550nm (yellow-green), matching peak sensitivity of human eye. This is the standard astronomical magnitude system.
B-band (Blue): Johnson B filter centered at ~440nm (blue light). Used when V magnitude is unavailable.
Magnitude Scale
The astronomical magnitude scale is logarithmic. Each magnitude step represents a brightness ratio of ~2.512x. The formula relating magnitude difference to brightness ratio is:
\[m_1 - m_2 = -2.5 \times \log_{10}\left(\frac{F_1}{F_2}\right)\]
where m is magnitude and F is flux. Lower magnitude = brighter object.
Color Index (B-V)
The B-V color index indicates object color and temperature:
\[B - V = m_B - m_V\]
Typical values: blue objects have negative B-V, white objects are near 0, yellow objects are near 0.6, and red objects are above 1.0. Reference: Color Conversion
Magnitude Notation
Each magnitude value is marked with (V) for V-band or (B) for B-band to indicate the photometric system used.
Visibility Guide:
• Naked eye limit: ~6.0 mag
• Binoculars: ~10.0 mag
• Small telescope (4"): ~12.0 mag
• Medium telescope (8"): ~14.0 mag
Coordinate System
Right Ascension (RA): Celestial longitude in hours:minutes:seconds (0h to 24h).
Declination (Dec): Celestial latitude in degrees:arcminutes:arcseconds (-90 to +90 degrees).
All coordinates are in the J2000.0 epoch (standard reference frame for year 2000).