Fremont Peak 10/13/07

by Steve Gottlieb


After bailing on Calstar, Bill Cone and I decided to observe locally on Saturday night. Where to go, though? With the concern of dewy conditions and water vapor mucking up the transparency, we procrastinated until the middle of Saturday afternoon, finally deciding to drive down to Willow Springs in the late afternoon. As a bad omen, though, I realized I had left my sleeping bag at home after driving a few miles on the freeway, so I turned around, grabbed my bag and gave Bill a call. He still hadn't left, so we went around some more about the best site to head for as sunset was approaching. After 10 minutes of hemming and hawing we decided to go with Willow Springs anyways instead of closer Lake Sonoma or Coe and I headed back onto 80 at Golden Gate Fields in Albany. But, as I drove past San Jose and Morgan Hill ominous looking clouds were hugging the coastal ranges and the sun was sinking low in the west. About this time, Bill called on my cell and suggested we give Fremont Peak a shot instead of the longer drive to Willow Springs. It's been over 10 years since my last visit to Fremont Peak (I was a regular there for awhile in the late '70's and early '80's), so figured it was time for a return visit.

I arrived at the Peak, looked around Coulter Row and the southwest lot but found no other amateurs set up. As there only appeared to be a few campers around, I set up along Coulter Row and Bill arrived about 25 minutes later as it was starting to get dark. A couple of minutes starting to set up, Bill looked startled as the realization settled in that he had forgotten one of his Plettstone struts back at home. Oops. I suggested we just observe together using my scope and that worked out well as it was fun to compare impressions and try to confirm marginal details. As far as the skies, we'll let's just say it was Fremont Peak on a clear night without fog. On the positive side, dew was not a problem, it was a fairly quiet Saturday evening (other than intermittent cars driving up and down the road) and seeing was good. No problem using up to 565x with sharp star images.

We first looked at several planetaries. Although the transparency was pretty mediocre, we were able to view several mag 14-15 planetaries. Aren't filters great? Bill had been chasing the Footprint Nebula for a few months, so I decided to take a look at that first, followed by a few relatively easy Abell planetaries and an easy Minkowski object.

Abell 2 = PK 122-4.1
00 45 36 +57 57.4
V = 14.5; Size 33"x29"
Picked up easily at 175x using a NPB filter. Appears as a fairly small, round disc ~30" in diameter. Once identified I was able to view the planetary unfiltered and noticed a faint star on the south edge of the rim. Also viewed unfiltered at 225x and noticed a similar 20" companion to the SW of the superimposed star. With a NPB filter, Abell 2 was sometimes slightly elongated N-S, ~33"x28". Located 5' S of a 2' pair of mag 8.3 (HD 4253) and 10 stars.

Abell 4 = PK 144-15.1
02 45 23.7 +42 33 05
V = 14.8; Size 22"
Swept up at 160x using a NPB filter as a faint, fairly small disc only 20"-25" diameter with an even surface brightness. Visible with direct vision continuously and seen without filter using averted vision. Forms the NW vertex of a triangle with a mag 10.7 star 2' SE and 3' NW of mag 8.7 HD 17052. At low power, located 40' ESE of M34.

Abell 81 = IC 1454
22 42 25.0 +80 26 32
V = 14.4; Size 34"x31"
Easily swept up at 175x, located 4' W of mag 7.0 HD 215867. Compared views unfiltered and with UHC, OIII and DGM Optics NPB filter. Best seen using OIII, though NPB gave the most natural view with brighter stars. Two faint mag 14/15 stars are very near the NE edge (brighter star barely off edge) with a brighter mag 13 star 1' SE. At 225x using the NPB filter, IC 1454 appeared round, ~25-30" in diameter with an impression of an irregular surface brightness. The rim sometimes appeared slightly brighter with a weaker center giving a very subtle annularity.

M 1-92 = Footprint Nebula
19 36 18.9 +29 32 50
V = 12.0; Size 8"x3"
Easily noticed in the field at 225x as a slightly soft "star", just 30" east of an orange mag 9.8 star. This star is the brightest in a small string of 3 stars oriented NW-SE. At 300x appeared only 4" in diameter with a very small, faint extension to the SE ("heel" of the Footprint). At 565x, the "heel" sometimes appeared detached, though was generally just a very low surface brightness swelling towards the SW.

Minkowski 2-55 = PK 116+8.1
23 31 52.7 +70 22 10
V = 14.4; Size 42"x36"
At 115x and OIII filter appeared as a fairly faint (perhaps slightly brighter and larger than IC 1454 = Abell 81), round disc, ~35" diameter with a crisp edge to the rim. Two mag 11 stars lie 1.2' ESE and 2' NE. Slight irregularity to the surface brightness. At 175x and NPB filter, subtle brightness variations were picked up with a slightly brighter knot or faint embedded star on the SE or E side.

Bill decided to call it quits after midnight and drove back home. As he left I remembered he had wanted to take a look at one of the M31 or M33 globulars, and although I knew the transparency was not good enough to go after really dim extragalatic globulars I revisted the king of the M31 globulars -- G1.

M31-G1
00 32 46.6 +39 34 41
V = 13.7; Size 0.6
Viewed at 450x and easily resolved the tight triple "star" that contains G1. The mag 13.5-14 globular was clearly nonstellar, though very small, ~8" diameter with a bright, quasi-stellar center and fainter halo. With direct vision the brighter center dominates and the halo fades. The globular forms the east vertex of a tiny equilateral triangle with two mag 14.5/15 stars 8" NW and SW.

I wanted to take a in depth look at one or two of the large HII regions in Cassiopeia or Cepheus and decided to work on IC 1805, the "Heart Nebula" and IC 1848, the "Soul Nebula". These objects are so large and contain lots of subtle structure that I spend over an hour on just IC 1805. I only started to work on IC 1848 before pooping out around 3:00 so I'll have to return to this object to complete the observation. Here's how they looked --

IC 1805 = "Heart Nebula"
02 32.7 +61 27
V = 6.5; Size 95x80
IC 1805 is a cluster (Cr 26) involved with a huge emission complex (LBN 654) dubbed the "Heart Nebula". The central cluster, Cr 26, is striking at 73x and consists of a 20' scattered group of mag 8 and fainter stars (about 17 stars mag 8-10.5). Embedded within the group is a smaller, fairly rich, 4'x2.5' oval ring with over three dozen stars. Most of the stars are located along the irregular ring, itself. On the SW side is the brightest mag 8 star, HD 15558, with a mag 10.5 companion at 10" (ADS 1920). This central clustering is richest around this HD star with 9 or 10 stars in total packed into a 1.6' area.

Adding an OIII filter, the cluster is encased in a fairly bright, irregular glow, ~12-15' in diameter and extending mostly to the east of the cluster. There appears to be dark lanes or obscuring dust involved as the surface brightness is quite irregular with brighter filaments within the glow. Fainter nebulosity extends to the east and then abruptly bifurcates into two branches heading NE and SE. There's a sharp border to the nebulosity at the split as the sky further east immediately darkens.

The stream of nebulosity to the NE extends for ~20' and then bends back sharply towards the west where it meanders for 30'-40', ending roughly 30' N of the cluster. Another 20' E of the bend at the NE corner is the fairly large open cluster NGC 1027.

The southern wing can be followed around in a huge loop. First it gently curves south or SSE for ~40' and then loops back sharply to the west (forming the southern boundary of the Heart) for at least 40', heading towards a distinctive N-S string of 5 stars with a length of 6' (this group is Mrk 6 = Stock 7). At the south end of Mrk 6 are two doubles, ?264 = 8.6/9.8 at 17" and a mag 10/11 pair at 17". At this point, the rim of this huge complex continues to the north and brightens in a 10' patch. It continues north, passing about 25' W of the cluster as it dims out close to NGC 896, a nearly isolated bright patch to the NW of the main structure.

At this point, I had traced around the entire outline of the "Heart Nebula" visible on wide-field images, scanning over 1.5 in length from north to south and over 1.25 in width from west to east. The entire outline, including the weaker interior glow, was also visible at 12.5x in the 80mm finder using an OIII filter although without the detail visible in the main scope.

NGC 896 and IC 1795 are parts of a fairly bright, detailed region at the NW corner of the huge IC 1805 HII ring. This complex is split into three or 4 distinct sections by dust lanes. The largest section is IC 1795, which extends mostly north of a mag 10 star for ~8'. To the west of the mag 10 star is a dust lane oriented NW-SE and beyond this lane to the west is a small, moderately high surface brightness patch (NGC 896) of 2' diameter. To the east of the star is another broad dust lane extending N-S and east of this lane is a fainter wash of nebulosity that streams to the north for over 15' in length. It passes through mag 9 SAO 12287 and just north of this star the nebulosity has a small, brighter patch. Initially, I thought the complex ended here on the NE side, but then additional fainter nebulosity was noticed spreading out to the west for several arc minutes increasing the total size to 15'-20' for both N-S and E-W directions.

IC 1848 = Soul Nebula
02 51.2 +60 24
V = 6.5; Size 60x30

18" (10/13/07): I only took a fairly quick look at this huge HII region ("Soul Nebula" or "Baby Nebula") at the end of the evening after a long examination of IC 1705 ("Heart Nebula"). In comparison, portions of this object clearly have a higher surface brightness using an OIII filter at 73x. Near the center is an E-W elongated, scattered group of stars (Cr 32), ~10'x4' in size. On the west end are two mag 7/8.3 with a number of fainter stars huddled nearby. About 60' to the ENE is another larger, scattered group (Cr 34). Weak nebulosity is evident throughout the field without a filter.

Adding an OIII filter greatly increases the contrast and nebulosity is fairly prominent in several different sections. About 20' E of the Cr 32 is a brighter, elongated patch. To the east of this patch is a dark lane or intrusion and on the eastern side is a brighter, 10' circular glow (IC 1871) with an irregular outline. IC 1871 is located roughly 45' ENE of Cr 32. This patch is irregular in surface brightness with brighter streaks. A larger region spreads out to the east of the cluster increasing the total length to over 1.5 degrees. I also noticed brighter regions of nebulosity to the west of Cr 32, but didn't take notes on this area or try to follow the entire outline of the complex.

At this point, Orion was rising pretty high in the southeast and after some quick peeks at Winter sky candy I realized this had turned out in the end to be quite a nice night.

Steve


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