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RA: 06h 09m 39s
Dec: +20° 29′ 18″
Ch: MSA:180, U2:137, SA:5
Ref: SIMBAD, NGC/IC, DAML02, Archinal&Hynes (2003)
Type: open cluster, 33rn
Mag: B=7, V=6.8
NGC 2175 is a very large roughly circular emission nebula which also includes NGC 2174 and IC 2159 (both of which see), and a star cluster which has inherited the NGC number, though there is no mention of it in the discovery notes. The nebula is centered on SAO 078049, though the brightest knot (which Bigourdan took for N2175; hence, the "corrected" RA in the IC2 Notes) is about three arcmin to the west-northwest. Auwers's note makes it clear that NGC 2175 is much more than just the knot: he gives dimensions of 25 arcmin by 8 arcmin, and specifically adopts the position of Lalande 11668 = SAO 078049 as that for the object. I have followed his lead.
Ced 67a (NGC 2175)
Position (1900): RA 6 3.7, Dec + 20 30
Star: 20 1284 (Mp=7.20, V=7.40, SpT=O6)
Spectrum of nebula: emission spectrum (observed)
Classification: Neb associated with mainly one star (which may be multiple) - star surrounded by a neb envelope with conspicuous structure (eg. IC 5146)
Notes: "a = NGC 2175 = GC 1366. Disc. Bruhns (Compare Auwers: Konigsherg Obs 34). FA 122. WP 45. (54, 88 Pl 22, 93 Pl 9, 114, 194, 216, 294, 366, 399, 482, 578, 630 Pl 35, 715). R. Nebulous cluster with the principal star +20'1284 = HD 42088. Alternative classification : A. 2. The object NGC 2174 probably refers to the northern part of the nebula."
Lynds, B.T. (1962) Catalogue of dark nebulae. Astrophys.J.Suppl.Ser. 7, 1-52. [also: computer datafile: VII/7A]
"A Catalogue of Estimated Parallaxes of 112 Nebulae, Open clusters and Star Groups", Vol 36 (4), p 107-115.
"large mass of diffuse nebulosity with nebulous star; 7.4 mag."
The RNGC (Sulentic and Tifft 1973) notes that this is a 7.0 mag cluster associated with nebulosity.
by Jim Lucyk: Sky&Tel. 4/71 p218, Astronomy mag. 2/86 p40, Deep Sky #5 Wi83 p14, Observer's Guide (Astro Cards) 1-2/88 p32.
writes: "The diffuse nebula NGC 2174 overlaps the open cluster NGC 2175. While the glowing cloud is perhaps twice the size of the 18' diameter cluster, it will probably challenge visual observers using anything less than a 12-inch scope. The cluster, on the other hand, is about 7th mag and as easy target for a 6-inch" It is possibly involved with the Gem OB1 association.
Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "6.8M; 18' diameter; 60-plus 8M members; reflection and emission nebulosity N2174 surrounds cluster mostly to N; use P-filter; small, faint OPN CL N2175-s just NNE."
(e-mail: firstname.lastname@example.org, web: http://www.west.net/~jbc/)
Instrument: 50-mm binoculars Location: Carpinteria, CA, USA
Light pollution: light Transparency: good Seeing: fair
Time: Wed Feb 5 04:30:00 1997 UT Obs. no.: 47
Not completely sure this is the object I swept up, but... What I saw in the 7x50s was a single bright star with a very faint glow glimpsed behind it. The glow was small in extent, almost subliminal. Comparing to photos of NGC2175 (the cluster) and NGC2174 (the nebula), I'm not sure which was responsible for the glow I perceived; the nebula is in the right spot but the cluster would presumably be more detectable with my small aperture.
Coe, using a 13" f/5.6, notes: "This cluster is marked as a large cluster on the south side of the NGC 2174 nebula. If that is so, then this object is pretty bright, very large, a scattered ringlet of 22 stars of mags 10 to 13. This is at 100X in the 13". However, there is a pretty bright, pretty small, very compressed cluster to the north of the 8th mag star about 10' of arc. At 220X from Sentinel on a 9/10 night it just resolved into 10 stars and a fuzzy backround. This compressed cluster is not marked on Uranometria 2000."
Observing site: Little Tycho Observatory
[6h 9m 48s, 20° 19m 0s] The field was found, but I see no cluster, just the Milky way. *Perhaps* a slight clump of 12... stars was seen, but nothing I would call a cluster. WikiSky: It's at the center of a faint nebulosity, drounded by the urban skies.
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