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Type: galaxy, S-Irr
Mag: B=13.9, V=13.3
Size: 1.7′ x 0.6′
NGC 5704 is probably = NGC 5708. There is no doubt that WH's object (II 649) is NGC 5708; his description matches, and his position is just about 1.6 arcmin north-northeast of the galaxy.
JH, however, has the number on the one observation of his in the area that does not apply to the galaxy. That one night, JH's position ends up almost exactly on the preceding star of a wide double (the position angle is about 100 degrees) -- is it possible that he mistook it for a nebula? His description, "F, S, R," supports this notion, with the shape being at variance with his father's "F, S, E nearly mer., r." Note, in particular, that WH has the galaxy extended north-south (as it actually is), not nearly east-west as the orientation of the double star would have it. His final comment ("r" = mottled) is probably due to the star superposed on the south- east edge of the galaxy, as well as the rather patchy nature of the object itself.
On that same night, JH has another observation of what he calls a "nova" which is nevertheless clearly the galaxy. The position agrees, and his description "F, pL, E nearly in merid.; gbM" does, too.
JH has one other observation that he credits to the first of these two objects, but he comments that the position is bad. He apparently did not notice that that "bad" position is identical to his two positions for NGC 5708 (the mean of his three positions is only 15 arcsec off the galaxy).
So, the only puzzle is the position of the object found by JH which received the NGC number 5704. This is the position given in GC and NGC, and as I noted above, is close to the western component of a double star. However, since there is only one galaxy here, and since it is clear that both Herschel's saw it, I am going to put both NGC numbers on the object. But we do have to keep in mind that JH claimed to have seen two nebulae here on one night, so it is still possible that we could claim NGC 5704 as the star.
Synonyms: H II-649
Discovered in 1787 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "F, S, E nearly in the meridian, resolvable."
The RNGC (Sulentic and Tifft 1973) notes that this is a nonexistent object. Their coded description reads NF DC.
The Messier objects
The Bennett objects
The Caldwell list
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