NGC Catalog
8373 objects in the NGC catalog
New General Catalogue
Author
John Louis Emil Dreyer (1852-1926)
Year
1888
Objekter
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.
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| Navn | Type | RA | Dek | Mag | Stjernebillede | Handlinger |
|---|
Om deep sky-data
Datakilde
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
Fotometriske systemer
V-band (Visual): Johnson V-filter centreret omkring ~550 nm (gulgrønt), svarende til det menneskelige øjes højeste følsomhed. Dette er det standardiserede astronomiske magnitudesystem.
B-band (Blue): Johnson B-filter centreret omkring ~440 nm (blåt lys). Bruges når V-magnitud ikke er tilgængelig.
Magnitudeskala
Den astronomiske magnitudskala er logaritmisk. Hvert magnitudetrin svarer til et lysstyrkeforhold på ca. 2,512x. Formlen, der relaterer magnitudeforskel til lysstyrkeforhold, er:
\[m_1 - m_2 = -2.5 \times \log_{10}\left(\frac{F_1}{F_2}\right)\]
hvor m er magnitude og F er flux. Lavere magnitude = lysere objekt.
Farveindeks (B-V)
B-V-farveindekset angiver objektets farve og temperatur:
\[B - V = m_B - m_V\]
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: Farvekonvertering
Magnitudenotation
Hver magnitudværdi er markeret med (V) for V-bånd eller (B) for B-bånd for at angive det anvendte fotometriske system.
Synlighedsguide:
• Grænse for det blotte øje: ~6.0 mag
• Kikkert: ~10.0 mag
• Lille teleskop (4"): ~12.0 mag
• Mellemstort teleskop (8"): ~14.0 mag
Koordinatsystem
Right Ascension (RA): Celestial longitude in hours:minutes:seconds (0h to 24h).
Declination (Dec): Celestial latitude in degrees:arcminutes:arcseconds (-90 to +90 degrees).
Alle koordinater er i J2000.0-epoken (standardreferenceramme for år 2000).