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NGC 5673 (12,468 of 18,816)

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NGC 5673

NGC 5673, LEDA 51901, MCG+08-26-041, UGC 9347, II 696, h 1838, GC 3931

RA: 14h 31m 30.87s
Dec: +49° 57′ 29.2″

Con: Bo÷tes
Ch: MSA:586, U2:77, SA:7

Ref: SIMBAD

(reference key)

Type: galaxy (in group), Sc

Mag: B=14, V=?

Size: 2.398′ x 0.489′
PA: 136°

History and Accurate Positions for the NGC/IC Objects (Corwin 2004)

NGC 5673 and IC 1029. It's clear that -- in spite of Dreyer's note (in his 1912 edition of William Herschel's papers) to the contrary (he was misled by John Herschel's position for the north-preceding galaxy) -- WH saw the south- following object of the pair. His position is very good, and his description "pB, S, E" leaves no doubt that it was the brighter of the two galaxies that he picked up in his sweep. It is also clear that John Herschel saw the north- preceding object. Again, his position is good, and his description "vF, pmE, sf a * 15m" is spot-on for the object.

Faced with the problem of whether to use William or John's position for N5673, Dreyer simply followed the GC. For this, Sir John adopted his own position, believing (correctly) that it is statistically more reliable than his father's. Also believing that there was only one nebula in the field, Sir John (and Dreyer after him) did exactly what I would have done in the same situation: place the GC number (to be followed by the NGC number), on the fainter of the two galaxies.

Bigourdan saw and measured both, though there is a typo in his 8 June 1899 description for NGC 5673: his comparison star is -1 min 48 sec -- not -1 min 58 sec -- away from BD +50 2091. Once this is corrected, his positions (re-reduced with respect to the Guide Star Catalogue positions for his comparison stars) agree very well with modern values from Dressel and Condon (used in RC3), and from the GSC. It's interesting to read his first description of IC 1029: "... the star near [N5673] mentioned in the GC description was not seen" (a very free translation by yrs trly). I think that he must have believed when he observed it that this object, quite the brighter of the two, was the GC (and NGC) galaxy. His estimates of the magnitude (12 and 12.8) of the star in his descriptions of N5673, by the way, are much more in line with today's magnitude scale than is Sir John's single estimate of 15. But we know that the scale was considerably stretched in Sir John's day, and was not rationalized until Pogson did his work in the mid-1800's.

In any event, we end up with the number NGC 5673 = h1838 on the fainter galaxy, and the brighter galaxy is IC 1029 = H II 696 = B 185. As I said, I believe that we should leave things this way. We have, after all, the authority of the GC, the NGC, and the IC behind the numbering. And I see no reason to introduce confusion if we don't have to (though I have done it in other cases).

In addition, if we adopt the other point of view and give Sir William historical precedence, then the north-preceding galaxy looses its GC and NGC numbers (though not its number in Sir John's 1833 list) altogether, and the south-following nebula becomes N5673 = I1029. There is no justification at all for transfering the number I1029 to the north-preceding object; this number was given to the south-following nebula by Dreyer, and there is no confusion of position or nomenclature for it in Bigourdan's observations, or in the IC.

Historical observations

William Herschel (c.1784)

Synonyms: H II-696

Discovered in 1787 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "pB, S, E."

Published comments

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a 14.0 mag galaxy. Their coded description reads EON,BM,EQDKLN.

Modern observations

Steve Coe

Steve Coe, using a 13" f/5.6, notes: "Pretty faint, pretty small, much elongated (3 X 1) in PA 135 and much brighter in the middle at 100X. Going to 165X will show off a stellar nucleus in moments of good seeing."

Brian Skiff

RC3: V=12.1/12.5 (pe), V=13.1/13.5 (pg).

15cm - mod f spindle @ 80x. 140x: 0'.8x0'.2 in pa145 w/mod even concen to rel

consp *ar nuc. thinly-tapered lens. m10 * 2' E. BS, 15May1991, Texas Star

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