Starship Asterisk*

https://www.spacetelescope.org/news/heic1907/ wrote:
<<The Southern Crab Nebula was first written about in 1967, but was assumed to be an ordinary star until 1989, when it was observed using telescopes at the European Southern Observatory’s La Silla Observatory.>>

https://en.wikipedia.org/wiki/New_General_Catalogue wrote:
<<The New General Catalogue of Nebulae and Clusters of Stars (abbreviated as NGC) is a catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. It expands upon the cataloguing work of William and Caroline Herschel, and John Herschel's General Catalogue of Nebulae and Clusters of Stars. The NGC contains 7,840 objects, known as the NGC objects. It includes all types of deep space objects, including galaxies, star clusters, emission nebulae and absorption nebulae. Dreyer also published two supplements to the NGC in 1895 and 1908, known as the Index Catalogues, describing a further 5,386 astronomical objects.

Objects in the sky of the southern hemisphere are catalogued somewhat less thoroughly, but many were observed by John Herschel or James Dunlop. The NGC had many errors, but an attempt to eliminate them was initiated by the NGC/IC Project in 1993, after partial attempts with the Revised New General Catalogue (RNGC) by Jack W. Sulentic and William G. Tifft in 1973, and NGC2000.0 by Roger W. Sinnott in 1988.

The Revised New General Catalogue and Index Catalogue (abbreviated as RNGC/IC) was compiled in 2009 by Wolfgang Steinicke.>>

Nitpicker wrote: ↑Wed Apr 24, 2019 11:57 am

Ann wrote: ↑Wed Apr 24, 2019 10:17 am

joe25 wrote: ↑Wed Apr 24, 2019 9:57 am Does this 'object' have an NGC designation ?

I guess not.

Wikipedia wrote about the Southern Crab Nebula:

Designations: V852 Cen, Hen 2-104, IRAS 14085-5112, PN G315.4+09.4, Wray 16-147, 2MASS J14115206-5126241

Apparent magnitude (V): 14.20

The Southern Crab Nebula is a 14th magnitude object. I don't think NGC lists objects that are generally fainter than, say, 12th magnitude.

Compare the Southern Crab Nebula with the "real" Crab Nebula, Messier 1. According to Wikipedia, the Crab Nebula is an 8th magnitude object. A faint 8th magnitude object, admittedly, but the Crab is still almost six magnitudes brighter than the Southern Crab. That's a lot.

Interestingly, the Crab and the Southern Crab appear to be at comparable distances from us, so the fact that the Crab Nebula is almost six magnitudes brighter than its southern "cousin" says something about the relative brightness of these two objects.

Ann

The angular size of the southern crab is roughly five times smaller, I think. So the difference in surface brightness would not be as great as the magnitude difference suggests, when compared with the northern crab. But I haven't done the sums.

Ann wrote: ↑Wed Apr 24, 2019 10:17 am

joe25 wrote: ↑Wed Apr 24, 2019 9:57 am Does this 'object' have an NGC designation ?

I guess not.

Wikipedia wrote about the Southern Crab Nebula:

Designations: V852 Cen, Hen 2-104, IRAS 14085-5112, PN G315.4+09.4, Wray 16-147, 2MASS J14115206-5126241

Apparent magnitude (V): 14.20

The Southern Crab Nebula is a 14th magnitude object. I don't think NGC lists objects that are generally fainter than, say, 12th magnitude.

Compare the Southern Crab Nebula with the "real" Crab Nebula, Messier 1. According to Wikipedia, the Crab Nebula is an 8th magnitude object. A faint 8th magnitude object, admittedly, but the Crab is still almost six magnitudes brighter than the Southern Crab. That's a lot.

Interestingly, the Crab and the Southern Crab appear to be at comparable distances from us, so the fact that the Crab Nebula is almost six magnitudes brighter than its southern "cousin" says something about the relative brightness of these two objects.

Ann

The nebula's dramatic stellar duo consists of a hot white dwarf star and cool, pulsating red giant star shedding outer layers that fall onto the smaller, much hotter companion.

joe25 wrote: ↑Wed Apr 24, 2019 9:57 am Does this 'object' have an NGC designation ?

Wikipedia wrote about the Southern Crab Nebula:

Designations: V852 Cen, Hen 2-104, IRAS 14085-5112, PN G315.4+09.4, Wray 16-147, 2MASS J14115206-5126241

Apparent magnitude (V): 14.20