Harold Corwin

IC 1480 = NGC 7607 is a double star within seven arcsec of Bigourdan's measured position. His description reads "Small cluster 20 arcsec in diameter in which I can distinguish at least two stars, perhaps accompanied by a little nebulosity."

Many of Bigourdan's "novae" which are nothing more than single or double stars carry that same note: "accompanied by a little nebulosity." There is almost always no trace of nebulosity around these stars and asterisms on the sky, so there may be some systematic problem with his observations at the limit of his vision. Perhaps he was just pushing that limit too hard, or perhaps he did much of his observing on poor nights (but that is not borne out by his notes about seeing and transparency). Whatever the case, it happened a lot.

The NGC number, which see, comes from Tempel, who independently discovered the "nebula" some years before Bigourdan. Tempel's position is also micrometrically measured, so there is doubt neither about the identity with the double, nor with Bigourdan's object.

It was not until I was putting the IC into NED in the spring and summer of 2005 that I tripped across the identity with the NGC object. Working through the catalogues over the previous years, I had measured the positions for the stars twice, once for the NGC number, then again for the IC, without noticing that the numbers pointed to the same objects. Perhaps there are more to be found. If so, I will find them as I continue working through the IC.

Now it is November 2018, and I am pretty sure that all the NGC/IC identities have been caught, if not by me, then by Steve Gottlieb, Wolfgang Steinicke, Malcolm Thomson, or Courtney Seligman. There are others, too, who have been plowing through these catalogues for many years, so further identity discoveries are unlikely.

But I could well be wrong -- I have been many times in the past!

― IC Notes by Harold Corwin

Harold Corwin

NGC 7607 = IC 1480 is a double star. The NGC object is one of Tempel's "nebulae" with a very good ring micrometer measurement. That pins down the star accurately, as does his note of a 16th magnitude star half an arcminute to the northeast.

The IC entry comes from Bigourdan, whose micrometric position falls within seven arcsec of the double. Curiously, the NGC object is missing from his big table. There is no entry for it, not even with his frequent, terse "Non vue" comment. See the IC number for more.

― NGC Notes by Harold Corwin

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