Harold Corwin

IC 5303 is a double star -- assuming that it is B351 as well as B350 as noted by Dreyer. B350 is one of seven of Bigourdan's new objects which have no detailed observations given in his main tables of differential positions (see IC 532 for more on these seven). He apparently found it on 5 October 1891, just about a week after he found B351, for which he does list an observation. Since the positions in his lists of new objects in his Appendix VII are the same for these two objects, the data probably refer to the same object. In this case, both numbers refer unambiguously to a double star.

Interestingly, Bigourdan's description mentions a possible double star in the center of the nebulosity. Many of the "nebulae" that he observed are nothing but stars. Why did he think so many of these faint single and double stars were nebulous? I speculated earlier about a slight imperfection in the optics he was using, combined with less than perfect seeing. But I think now it was purely a seeing problem. Bigourdan would have known his optics intimately, and would surely have been able to compensate for any problems with them.

― IC Notes by Harold Corwin

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