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RA: 18h 33m 36.1s
Dec: +67° 06′ 39″
Ch: MSA:1065, U2:30, SA:3
Ref: NGC/IC, NED
Type: galaxy, Sbc
Mag: B=14.4, V=13.6
Size: 0.9′ x 0.4′
NGC 6677 and 6679 = IC 4763. Malcolm and I have fussed over this field for several years now, and have been unable to come to a consensus. So here is my take on the area.
The two brightest galaxies here -- Malcolm's objects "A" and "B" -- were seen by Swift, Bigourdan, and Howe. (Kobold also has an observation of NGC 6677 in the Strassburg Annals, Vol. 3, 1909, but his comparison star has a high proper motion which makes the derivation of an accurate position more difficult.) I agree with Malcolm that A must be NGC 6677, but am pretty well convinced that B is NGC 6679 = IC 4763. Here's why:
1) As I always do for identification problems, I determined as accurate a position as I can for every object bearing on an identity question. In this case, this meant reducing Bigourdan's micrometric observations, and digging positions out of the Guide Star Catalogue. Here are the results for Malcolm's three objects (positions are for the equinox 1950.0):
Galaxy NGC/IC RA Dec Source Notes A N6677 18 33 39.20 +67 04 09.8 GSC 18 33 38.83 +67 04 11.3 Big 5 Sept 1891 only 18 33 40 +67 04.1 Howe B N6679=I4763 18 33 33.29 +67 05 47.1 GSC 18 33 33.58 +67 05 44.8 Big 18 33 35 +67 05.7 Howe C --- 18 33 34.36 +67 06 21.8 GSC
Notice that I have used Bigourdan's observations only from the night of 5 Sept 1891 for NGC 6677. His observations on 25 June 1897 refer to the star southeast of the galaxy. I also suspect that his comparison star (BD +66 1115 = GSC 4227-00549) has a relatively large proper motion as there is a systematic offset of +0.24 sec and -7.8 arcsec between his positions and the GSC positions for all the objects for which he used this star as a comparison. I've corrected his positions in the table above for these offsets.
The excellent agreement between Bigourdan's, Howe's, and the GSC positions convinces me that the two micrometric observations from each of the early observers do indeed refer to Malcolm's objects A and B. Furthermore, their descriptions also make sense -- and agree with Swift's -- if we note one additional fact: object B is in fact a close double galaxy. Object C is more than 30 arcsec north of B, which puts it much too far away to be part of the object that Howe measured as NGC 6679: "This is a nebulous D * of mags 12.5, distance 5 arcsec, [position] angle 60 deg." Bigourdan's description of it as a double star, one that he could not resolve at 344X, also points to the close pair as the actual NGC 6679 -- and adds support to the evidence from his measured position that the pair is equal to Big 333 = IC 4763 (it is, of course, clear that Bigourdan himself realized this).
All of this evidence, combined with Swift's own descriptions (in his papers 1, 3, and 9) seem to me to pin down the identifications without much doubt. I've not taken Swift's own positions into account as we know that they are not very good. In this case, Howe has noted that Swift's declination for N6679 in the NGC is out by 8.5 arcmin. Swift corrected this by 10 arcmin when he finally published the observation in AN 3004, but by then, the damage had been done.
The RNGC (Sulentic and Tifft 1973) notes that this is a 13.5 mag galaxy. Their coded description reads EL,UHISB,DKPCHS NRCT.
The Messier objects
The Bennett objects
The Caldwell list
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