IC 4648
DSS image of IC 4648
Overlaid DSS image of IC 4648, 60' x 60' with north at top and west to the right

Aladin viewer for the region around IC 4648

Type  Double Star
Right Ascension  17h 16' 10.1"  (2000)
Declination  43° 51' 45" N
Constellation  Hercules
Observing Notes

Harold Corwin

IC 4648 is a double star two degrees south of the IC position. When I first went over this, I found that I did not have Bigourdan's Comptes Rendus list where this object was first announced. So I did not know if he was responsible for the two-degree error, or if Dreyer was. In early March 2014, Courtney Seligman wrote to say that he had found an on-line copy of the CR paper, and that that is the source of the erroneous position, not the second IC.

In Bigourdan's big publication of his observations, he has the correct positions and estimated offsets for this object, so it is easy to identify at the correct declination.

In addition, his description reads "Pretty nebulous object; could be a small cluster in which I can distinguish a double * (13.3 + 13.4; 270 degrees; 12 seconds to 15 seconds)." This description fits the double perfectly. The fainter star is to the west and looks like it itself is a merged double.

Finally, this object (along with about a dozen others) ended up with two entries in Bigourdan's list of new nebulae; it is B. 428 and B. 540. I suspect this is a bookkeeping error as Bigourdan has only one observation of the double on 1 June 1897 in his big list.
IC Notes by Harold Corwin
Other Data Sources for IC 4648
Associated objects for IC 4648
Nearby objects for IC 4648
7 objects found within 60'
IC 4645 Messier 92 NGC 6323
NGC 6327 NGC 6329
NGC 6336

Drawings, descriptions, and CCD photos are copyright Andrew Cooper unless otherwise noted, no usage without permission.

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IC 4648