206 



OBSERVATIONS ON NEBULA 



Sir William Herschel; Second Catalogue of 1000. Phil. Trans, 1789, Part II, 



Cl. 



No. 



Date. 



Star. 



Diff. of R. A. 



Diff. of Decl. 



No. of 

 Obs. 



Remarks. 



IV. 



41 



May 26, 

 1786. 



14 Sagittarii 



Prec. 



ll-»58' 



South 



P15' 



1 



A double star with extensive nebulosity of 

 different intensity. About tlie double star 

 is a black opening resembling the nebula 

 in Orion in miniature. 



Sir William Herschel; " On the places o/145 new Double Stars." Mem. Ast, Soc, Vol. I., 



Part I., 1822. 



(40.) 566 sweep. May 26, 1786. A double star within neb, IV. 41. 14 Sagittarii prec. ll" 58% 

 south 1° 15'; R. A., 17'> 49» 30'; P. D., 113° 1' 



Sir William Herschel; Astronomical Observations relating to the Construction of the Heavens, ar- 

 ranged for the purpose of a critical examination, <J-c." Phil. Trans. 1811, Part II. Under the 

 11th division " of treble, quadruple, or sextuple nebula," the example adduced is that of this nebula, 

 as follows: 



Among the treble nebulae there is one, namely, V. 10, of which the nebulosity is not yet separated. 

 " Three nebulae seem to join faintly together,'^ forming a kind of triangle; the middle of which is less nebu- 

 lous, or perhaps free from nebulosity^; in the middle" of the triangle is a double star of the second or third 

 class ; more faint nebulosities are following"*." 



' Mr. HerscheVs and Mr. South' s Observations of the apparent Distances and Positions of 380 double 

 and triple Stars." — Phil. Trans. 1824, Part II. In the " Supplementary Catalogue of Twenty," 

 less perfectly measured than the rest, on account of uncommon difficulty, <SfC., is a measure of the 

 central star: 



No. CCCLXXIX. R. A. 17'' 52- ; Decl. 22° 58' S. 40 of the 145. 



Double; 9th and 10th ' magnitudes. 



July 11, 1823. Five feet Equatorial. 



Position = 61° 45' i s p ; Distance = 10". 952 i single measures. " South." 



May be easily measured in the 7 feet, but in its present place it cannot be directed to it. 



Sir J. F. W. Herschel. " An Account of the Actual State of the Great Nebula in Orion, compared 

 with those of former Astronomers." Mem. Ast. Soc., Vol. II., Part II., 1826. In a note on p. 490 

 he says: 



"However, in the nebula R. A. 17'' 52", N. P. D. 113° 1' in Sagittarius, which belongs to the same 

 class of objects as that in Orion, the idea of an absorption by the double star in its middle is very forcibly 

 suggested. Tliis nebula is broken into three parts, and the three lines of division meet in a vacancy', in 

 the midst'' of which is situated the double star. This curious object has, perhaps, a proper motion. 



Art. 17., Aug. 1 and 9; Art. 43. 4. 



' Art. 45. 2. 



d Art. 61. 



• Art. 36. 



