sponsored by psychohistorian.org
RA: 23h 27m 22s
Dec: −00° 11′ 12″
Ch: MSA:1280, U2:259, SA:17
Ref: Corwin (2004)
Mag: B=?, V=?
NGC 7667, NGC 7668, NGC 7669, and NGC 7670. Father Angelo Secchi was a Jesuit priest who worked at College Romain in the mid-1800's. He is remembered today primarily as a pioneer in spectral classification of stars, and for his studies of the sun: he was among the first to photograph the corona during an eclipse, and also was the first to attempt to deduce the interior structure of the sun. It's fair to say that he was -- pun fully intended -- a father of stellar astrophysics.
In 1866, he published in AN 1571 a short list of fourteen new nebulae that one of his fellow Jesuits, Brother Ferrari, discovered during a (fruitless) search for Biela's Comet from 11 November 1865 to 18 January 1866. Father Secchi has this to say about the 9.5-inch Merz equatorial at the College Romain, "From this study, we have convinced ourselves that the refractor at our observatory is at least as keen and powerful as the Herschels' telescopes..." (translated by me from his French original). Also, he says that they "fitted [to the telescope] a large eyepiece which gives a 27 arcmin field." (My thanks to Wolfgang Steinicke for digging out the size of the telescope.)
Back to the fourteen new nebulae. I searched near the nominal positions on the POSS1 prints for all of these, and was unable to find any trace of eight of them (NGC 7565, N7613, N7614, N7666, N7667, N7668, N7669, and N7670). There are good candidates for three others (N7683, the only one of the objects whose position was determined by actual comparison to a star, N7738, and N50), and poor candidates for the remaining three (N7663, N7739, and N116). Secchi (or Ferrari) also "corrects" WH's positions for two nebulae, N157 and N7648. His positions for those are indeed better than Herschel's -- but they don't help us find the other missing objects in his list.
If we take mean offsets from modern positions for the "good" candidates -- excepting N7683 for which the position comes from a different method -- and the two corrected WH galaxies, we find systematic offsets of -5 seconds of time, and -1 arcmin 10 arcsec in Dec. The standard deviations on these numbers (+- 18 seconds and +- 26 arcsec) suggest that the RA offset is not significant and that the Declination offset is barely significant. But even that does not help us find the missing objects.
Reading more of Father Secchi's note, I learned why the positions are so bad. "The position is determined from the setting circles of the equatorial, corrected for instrumental errors, simply by placing the nebula in the center of the field." Secchi, however, also says that he verified each of the nebulae after Brother Ferrari found them. He must have done this on the same nights as their discovery since he never would have recovered them otherwise. Since Secchi gives no equinox in his note, I, like Dreyer before me, have assumed that his positions refer to the equinox at the date of observation, i.e. 1866.0 give or take a few weeks. I adopted 1866.0.
Specifically for NGC 7667 and its cohorts: there is nothing at all near the single nominal position that Secchi gives for them, and only one or two of the galaxies within a degree of that position are bright enough to have been seen with a 9.5-inch telescope.
However, Steve Gottlieb has suggested that some of the knots in the arms of UGC 12578 might be N7668, N7669, and N7670 which Secchi says "surround" N7667. These are much too faint for a 9.5-inch telescope, but the galaxy itself is quite bright enough to be one of Secchi's objects, in spite of having a pretty low surface brightness. However, it is 3 minutes off in RA and nearly five arcmin in Dec from the nominal position, so it would be a stretch to point to this object.
There are also three other objects within 13.5 arcmin of it that might be Secchi and Ferrari's other three nebulae: UGC 12589, and the double stars at 23 21 54.6, -00 12 35 and 23 22 12.5, -00 21 42 (1950 positions). All are northeast of U12578, though, and Secchi's description clearly translates as "Very faint: the other three surround the 9th [in the list = N7667] in the field." So, U12589 and the double stars are pure guesswork, and I don't think that I'd want to stake my life on them -- or even on U12578 being N7667.
The RNGC (Sulentic and Tifft 1973) notes that this is a 14.0 mag galaxy. Their coded description reads PEC,DIF IRRNEBW3BKNS.
The Messier objects
The Bennett objects
The Caldwell list
DOCdb is still in beta-release.
Known issues, feature requests, and updates on bug fixes, are here:
Found a bug? Have a comment or suggestion to improve DOCdb? Please let us know!
DOCdb is a free online resource that exists to promote deep sky observing.
You could help by sharing your observations, writing an article, digitizing and proof-reading historical material, and more.
Everything on DOCdb.net is © 2004-2010 by Auke Slotegraaf, unless stated otherwise or if you can prove you have divine permission to use it. Before using material published here, please consult the Creative Commons Attribution-Non-Commercial-Share Alike 2.5 License. Some material on DOCdb is copyright the individual authors. If in doubt, don't reproduce. And that goes for having children, too. Please note that the recommended browser for DOCdb is Firefox 3.x. You may also get good results with K-Meleon. Good luck if you're using IE. A successful experience with other browsers, including Opera and Safari, may vary.