NGC 2174* (IC 2159, Sh2-252) Bright Nebula* in Orion

Located at: RA 06 hours 09 minutes 42 seconds, Dec +20 degrees 29 minutes 00 seconds

Size: 29' x 27' Magnitude: -- Class: Emission (Sharpless) 3 2 3

North is up

West to the right

Telescope:

 8" f5 Newtonian reflector

Camera:

 ST-8XME, self-guided, binned 1x1, temp -20c, camera control MaxIm DL 4.56

Image:

Lumicon Deep Sky filter, 480 minutes (48 x 10 minute subs), 03/24/26/27/28/2008; seeing 2.6-4.2 FWHM per CCDStack

Processing:

CCDStack 1.3.2, Photoshop 7.0

Location:

 Rolling Roof Observatory, Thousand Oaks, CA 91360 (+34d 13m 29s -118h 52m 20s)

Notes:* This bright nebula is in an interesting region of the winter Milky Way. Situated in northernmost Orion, NGC 2174 is one of many nebulous regions that include 'The Cone' area to the south, and the IC 443 & IC 444 complex to the north.

The small open cluster NGC 2175 (5.0', mag --, Cl: II 2 p n) is to the northeast (upper left), and is involved in the NGC 2174 nebulosity ... However, my charting software (Megastar v5.0.13) lists the 'cluster like' object northeast (upper left) of the bright nebula NGC 2174/75 as "NGC 2175.1", @ 06h 10m 53s, +20d 36m 36s. The CDS image for the coordinates lists 47 objects within 10 minutes, only one of which is listed as an Open Cluster. The CDS designation is C 0607 +206, with aliases of C 0607+206, Cl Pismis 27, and NGC 2175s.

See the CDS data for NGC 2174 ...

However, this information from the NGC / IC Project:

Contemporary Visual Observation(s) for NGC 2174

NGC 2174 = Ced 67a = LBN 854 = Sh 2-252
06 09 23.6 +20 39 34
Size 40x30

17.5" (1/16/02): at 64x and OIII filter, this is a beautiful, detailed 
nebulosity surrounding a mag 8 star (SAO 78049), extending at least 20' 
diameter.  The OIII filter gives a dramatic contrast gain.  With averted vision 
and careful viewing, the outer borders extend to ~25'.  Structure includes 
interior streaky dark lanes visible to the west of the star.  The rim is 
slightly brighter or has a higher contrast to the western edge but slightly more 
nebulosity is visible on the following side of the star.

Without a filter at 64x, I was surprised to immediately notice a moderately 
bright 3' round glow, situated ~11' NNW of SAO 78049 near the NW edge of the 
main glow.  Interestingly, this patch of nebulosity is more prominent than the 
main body without a filter and is probably the section of the HII complex 
visually discovered by Stephan!  It seemed quite strange that this patch had 
such a different filter response and dimmed significantly with the OIII (mainly 
reflection component?).  A curving arc of stars is situated along the north side 
of the glow.  The entire nebula is situated among a scattered group of stars, 
which is often mistaken for N2175.  Located 1.4 degrees ENE of Chi(2) Orionis.

17.5": very large, irregular nebulosity surrounding mag 8.0 SAO 78049.  Dark 
lanes are evident west of the star, appears very streaky.  A bright small 
unresolved knot is 3.2' ENE of the bright star using an OIII filter [this is 
N2175].

13": very bright with filter, very large, surrounds a mag 8 star, sky very dark 
off W side.  West of the star the nebula is mottled and streaky with a bright 
region near the N edge.

N2174 was discovered by Stephan (Object #7, List IX, Comptes Rendus, vol 87, p. 
869).  His description does not describe the entire nebulosity or a scattered 
cluster but rather a small patch of nebulosity (without the accents): 
"excessive., excess., faible (a peine observable); a l'interieur d'un triangle 
forme par trois petites etoiles".

He gives a 1878 position of 06 02 07.47, +20 40 54.4 which precesses to 06 09 
24.0 +20 39 53 (2000), and falls on the NW side of the nebula.  This probably 
needs a small correction in declination based on his reference star, but is 
still accurate enough to clearly identify a small brighter patch of nebulosity.  
His three stars are mag 13-14 in GSC and the knot of nebulosity is quite 
prominent on DSS just following the middle of these three stars.  This star has 
a GSC position of 06 09 21.9 +20 39 30 (2000) and Stephan's knot appears only 
30"-40" in diameter.

- by Steve Gottlieb
Historical Research Notes / Correction for NGC 2174
NGC 2174 is one of the knots in NGC 2175, which see.
 - Dr. Harold G. Corwin, Jr.

Contemporary Visual Observation(s) for NGC 2175

NGC 2175 = Ced 67a = LBN 854 = Sh 2-252 = Cr 84
06 09 39.5 +20 29 15
Size 40x30

17.5": See description for N2174.  Although the scattered group of stars 
involved with the HII region is identified as N2175,  the NGC description (from 
Auwers and Bruhns) does not refer to a cluster but rather a "*8m in neb (Auw No 
21)".  The position given is 10' south of N2174 and 16 tsec east.  But in the IC 
2 notes and correction, Dreyer gives a correction in RA from Bigourdan to 06 01 
32.  This places N2175 at 06 09 52 +20 29.1 (2000) and is just 1' south of the 
brightest section of the nebula (about 3' ENE of mag 8 SAO 78049).

- by Steve Gottlieb

Historical Research Notes / Correction for NGC 2175

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. - Dr. Harold G. Corwin, Jr.
"Star Clusters", by Brent Archinal and Steven Hynes, agrees that  the NGC 2175 designation should be for the bright nebula ...
However, in the Notes, "Star Clusters" indicates the the possible cluster should be called Collinder 84,Lund 208, OCL-476, OCISM 106, (4) NGC 2175, C0606+203.