Glen C

It is interesting to compare the Herschel's 18.5" speculum reflector with Lewis Swift's 16" refractor. Swift's magnitude limit for galaxies was about 1 mag fainter.

There are more than 300 DSO in Dunlop's 1826 catalogue of southern clusters and nebulae. Here is a list of 150 DSO from his catalogue. Thirty-three of these were found by other observers. Dunlop_150.pdf

If you count all the clusters, all the nebulae and galaxies brighter than magnitude 13 in both the NGC and IC catalogues the results are: 1714 were found by William Herschel with an 18.5” speculum reflector in the UK 1068 were found by John Herschel with an 18.5” speculum reflector in the UK and at the Cape 278 were found by James Dunlop with a 9” speculum reflector in Australia 197 were found by Lewis Swift, most of them with a 16" refractor in the USA 130 were found by DeLisle Stewart on photos made with a 24" refractor in Peru and 104 were found by Edouard Stephan with a 31" Foucault reflector in France The remaining 97 observers found less than 80 objects each. The above data is from Dr Wolfgang Steinicke http://www.klima-luf...cic/ngcic_e.htm

Posting this again because the first post has black lines across it James Dunlop (1793-1848) has not been mentioned in this forum, I think he deserves to be. I made a list of the brightest 100 open clusters, 100 globular clusters, 100 planetary nebulae larger that 11” and 200 galaxies in the NGC and IC catalogues. Who discovered these 500 objects? 100 brightest Open Clusters Number found, Name 28 William Herschel with an 18.5” speculum reflector 16 Nicolas-Louis de La Caille with a 0.5” refractor 10 James Dunlop with a 9” speculum reflector 10 John Herschel with an 18.5” speculum reflector 10 Giovanni Battista Hodierna with a small refractor 6 Charles Messier with a 3.5” refractor 14 others found 5 or less of these 100 OC 100 brightest Globular Clusters 34 William Herschel 24 Dunlop 15 Messier 15 others found 5 or less of these 100 GC (John Herschel 3) 100 brightest Planetary Nebulae larger than 11 arc secs 31 William Herschel 17 John Herschel 16 Williamina Fleming using spectra and photos 17 others found 5 or less of these 100 PN (Dunlop 3, Messier 2) 200 brightest Galaxies 109 William Herschel 26 Dunlop 18 Pierre Mechain with a 3.0” refractor 14 John Herschel 10 Messier 15 others found 5 or less of these 200 galaxies Nebulae are not included because their magnitudes are not available in many cases. The four main discoverers of these 500 bright NGC and IC objects were William Herschel (271 from Slough, UK), James Dunlop (63 from Parramatta, NSW), John Herschel (44 from Slough and Cape Town) and Charles Messier (33 from Paris). The two Herschels and Messier are famous, Dunlop is not. He observed from the back of 91 Marsden St. Parramatta, NSW, Australia in 1826 with a homemade 9” reflector. The above data is from Dr Wolfgang Steinicke http://www.klima-luf...cic/ngcic_e.htm

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