On Thursday, December 28th, I met Jim Shields and Robert Leyland for a very enjoyable evening at Lake Sonoma. Conditions were excellent with transparency around mag 6.5 with steady images up to 400x and no dew or wind to deal with. We lost about an hour in the mid-evening when a band of clouds swept over from the west but otherwise had a great time chasing down faint fuzzies. Here are a few highlights --
The Giant Molecular Cloud in Taurus/Auriga --
IC 2087 = Cederblad 38 = LBN 813
04 40 00.0 +25 44 32
Size 4'
17.5": this is an unusual reflection nebula embedded in the Taurus-Auriga molecular cloud which at 450 light-years is the nearest large stellar nursery. At 100x unfiltered IC 2087 is a fairly faint direct vision object, moderately large, round, 3'-4' diameter. Fairly well defined although edges fade into background. What is the striking is the location - only four brighter stars are visible in the 50' field with a complete lack of fainter stars down to mag 15! Surrounding field also show evidence of very high obscuration (extinction about 5 visual magnitudes in the vicinity) and the region is packed with infrared sources associated with the dark cloud.
IC 2087 was found by E.E. Barnard ("On a Nebulous Groundwork in the Constellation Taurus", ApJ, 25, p218, 1907). His plate shows a long winding dark lane with a small nebulous region surrounding a couple of stars within the dark lane. The nebula was first seen visually on January 18, 1892 while observing a comet and described as "excessively difficult".
A galaxy trio in Orion --
IC 412 = UGC 03298 = MCG +01-14-034 = CGCG 421-041 = VV 225b
05 21 56.7 +03 29 11
V = 13.6; Size 1.0x0.7; SB = 13.0; PA = 30d
17.5": this is the NW member of an unusual close pair of interacting galaxies with IC 413 -- just 35" separation (in PA 115°) and both members appearing to extend from a mag 12 star (30" from centers to star)! Both galaxies are faint, very small, slightly elongated, ~25"x15", with small brighter cores. IC 412 is elongated SSW-NNE and 30" SW of the mag 12 star - with the NE end just west of the star. IC 413 appears similar to IC 412 - ~25"x15", slightly elongated NW-SE with a small brighter core. The NW tip of the galaxy is virtually in contact with the mag 12 star. Located 6' SSW of mag 7.6 SAO 112679 and 14' WSW of the (32") mag 5/7 double 23 Orionis.
A third galaxy, IC 414, is in the field 8.5' south forming the poor cluster WBL 114. It appeared faint, small, round, 25" diameter. Located 9' S of the IC 412/412 pair and 2' NW of mag 9.4 SAO 112675.
A contrasting pair of galaxies in Cetus, NGC 337 and NGC 337A--
NGC 337 = MCG -01-03-053 = IV Zw 35
00 59 50.3 -07 34 43
V = 11.6; Size 2.9x1.8; SB = 13.3; PA = 130d
17.5": fairly bright and large, elongated 3:2 NW-SE, ~1.8'x1.2', broad concentration. The appearance is asymmetric -- with a noticeably mottled or irregular surface brightness. Brighter knots within the halo are also clearly visible at moments. The visual impression matches well with the DSS image which shows a chaotic structure with a number of large HII knots. A large, dwarf spiral, NGC 337A, lies 27' E. It appeared very faint and fairly large. Just a low surface brightness glow centered just 1.2' NW of a mag 12 star. The edge of the halo is very ill-defined but appears ~2' diameter (larger than N337 26' due west) and there was only a very slight central brightening.
A stellar planetary discovered in 1982 by MacConnell
Mac 2-1 = PK 205-26.1
05 03 41.8 -06 10 03
V = 14.9; Size stellar
17.5": easily picked up at 100x as a mag 14.5 "star", situated between two mag 11 stars oriented NW-SE with a 3.5' separation. The planetary is just over 1' SE of the NW star. Very good contrast gain with an OIII filter (at least 2 magnitudes) compared to the two brighter star which are less than a mag brighter with the filter. Appears stellar up to 380x.
A reflection nebula once thought to be a galaxy
vdB 54 = MCG -01-15-003
05 41 54.8 -06 15 09
V = 9.5
17.5": this reflection nebula appears as a faint, circular, 1.5' glow around a mag 9.5 star. The halo appears to fade smoothly into the background. This object is listed in the MCG as a galaxy! (M-01-15-003).
A compact planetary once listed as a double star
J 900 = PK 194+2.1
06 25 57.3 +17 47 27
V = 11.7; Size 12"x10"
17.5" (12/28/00): At 280x appears a bright, compact, hi surface brightness disc, ~8" in diameter with a bluish color. Forms a close double with a mag 13 star off the south edge (11" from center). At 380x, a brighter central spot was highly suspected several times and the planetary was very slightly elongated ~N-S.
This object was found by Robert Jonckheere, a French astronomer, and double star observer. He made this discovery in 1912 while using the 13" refractor at the University of Lille to examine the 900th double star on his list.
A stellar nursery in Orion next to NGC 1999 --
Herbig-Haro 1 and 2 are among the brightest H-H objects in the sky. This unusual class of objects was first discovered by George Herbig and Guillermo Haro 50 years ago and consists of highly collimated bipolar outflows of partially ionized plasma. We're actually looking at the first visible signs of otherwise hidden star formation! In this case, the embryonic source is completely obscured between HH 1/2.
As a bonus, this challenging object is in the same field as one of my favorite winter objects, NGC 1999. This is a bright, high surface brightness emission nebula surrounding a mag 10 star about 2' diameter. What's remarkable is a prominent, curved, irregular black patch (referred to as a globule) which wraps around the west side of the central star! The nebulosity is weakest on the SE side of star. The high surface brightness easily allows powers of 280x-500x with my 17.5" to examine this dark feature. Next up was a glimpse at nascent star birth!
Herbig-Haro 1
05 36 20.4 -06 45 10
17.5": At 380x, Herbig-Haro 1 is the fainter of a pair of HH objects close to NGC 1999. Only visible for moments and appeared virtually stellar. The observation was very hampered by N1999 just 2.5' N so it is essential to keep NGC 1999 off the edge of the field.
Herbig-Haro 2
05 36 25.4 -06 47 12
17.5": at 280x-380x Herbig-Haro 2 appeared very faint, very small, ~10" diameter. Once identified I was surprised it was not difficult to view with concentration and averted vision. This is the brightest HH region and is situated just 4.3' due south of NGC 1999! Forms a pair with HH 1 2.4' NNW.