Willow Springs 11/18/06

by Steve Gottlieb

Last Saturday night (November 18th), I took a chance on mixed weather prospects and headed south to the Willow Springs property of Bob Ayers, meeting Mark Wagner, Ray Cash and Charlie Wicks. Mark and Ray had just preceded me when I arrived and we were pleased to see a bank of clouds far to the north, but clear dark-blue skies overhead. Conditions were nearly ideal (very dark and very steady) for the first three and half hours until 10:00 PM and then clouds filtered over for the next two hours. Bob decided to pack it in and head back home and that seemed to appease the weather gods as we had perfectly clear weather again until 3:30 when we were exhausted.

It was good galaxy hunting conditions as stars were pinpoints at 280x and the background quite contrasty, making it easy to pick out tiny galaxies within clusters. So, that's mainly where I spent my time. Splashed across the fall skies is a river of galaxies beginning in Pisces at the NGC 383 group and flowing towards the east-northeast. This river contains a number of congested spots where groups and rich clusters of galaxies huddle together. A few degrees to the east of the NGC 383 group is another dense clump of galaxies that forms the NGC 507 cluster and over the border into Andromeda we find the NGC 536 clan. Continuing further east-northeast, several rich clusters mark the way including Abell Galaxy Cluster (AGC) 262 , AGC 347, NGC 1129 cluster and AGC 426 (Perseus Cluster). At a distance of nearly 300 million light years, the Pisces-Perseus supercluster is one of the largest known structures in the universe and stretches across nearly 40 of the fall skies. And it would likely continue further if it did not become lost (at least at optical wavelengths) behind the veil of dust in the Milky Way (more at the end).

I started off the evening with the Pisces Group, located at the west end of the Pisces-Perseus supercluster. This group contains 5 relatively bright NGC galaxies in a striking chain and a school of fainter galaxies swimming nearby. From south to north here are the main players --

NGC 384: moderately bright, fairly small, irregularly round, 0.6'x0.5', fairly well concentrated with a small bright core. At the south end of the Pisces Group with N385 1.7' N.

NGC 385: moderately bright, fairly small, round, 1.0' diameter, strong concentration with a bright 20" core. Appears slightly larger and brighter than nearby N384.

NGC 383: fairly bright, moderately large, irregularly round, 1.3' diameter, broadly concentrated to a bright core which increases to a 6" nucleus. Forms an interacting pair with N382 30" S of center. This galaxy is the brightest and largest member of the Pisces Group and is surrounded by 10 galaxies within 8'!

NGC 380: moderately bright, fairly small, round, 40" diameter, sharply concentrated with a very small, very bright core. Forms a 2.2' pair with N379 and 4.5' NNW of N383.

NGC 379: moderately bright, fairly small, elongated 3:2 N-S, 0.8'x0.5', broad concentration with a slightly brighter core. Forms a similar pair with N380. This galaxy is at the north end of the "Pisces Group" centered on N383.

In the same 225x field, I also found NGCs 373, 375, 382, 386, 387, 388 for a total of 9 NGC galaxies. The faintest of these are NGC 373 and 387 with catalogued B magnitudes of 15.9 and 16.5 attesting to the dark skies at Willow Springs.

The rich galaxy cluster, Abell 119, can be found by panning 50' east of the 4.8-magnitude star 20 Ceti. This cluster resides a mind- boggling 600 million light years from home and is one of the most distant clusters easily accessible in an 18-inch scope. Back in the fall of 1988 from the Sierra foothills (Fiddletown), I located 6 members in my 17.5-inch. As even the brightest members are not catalogued in the NGC or IC, I thought I was doing pretty well, but from Willow Springs (and an extra half-inch of aperture!), a dozen galaxies were identified. Here are my notes on the trio of brighter galaxies in the core of the cluster --

UGC 579: this cD galaxy (a class of huge ellipticals that grow through cannibalizing smaller cluster members) is the brightest member of AGC 119. At 220x it appeared moderately bright, fairly small, round, 0.8' diameter, broad concentration with a slightly brighter core. In the core of the cluster is a nest of faint galaxies surrounding UGC 579 and UGC 583 (located 2.4' ESE).

UGC 583: the second brightest member of AGC 119 appeared fairly faint, small, round, 0.4' diameter, small bright core, fairly high surface brightness. Located 2.4' ESE of UGC 579. Forms a double system with CGCG 384-37 at the south edge. The two brightest members in the core form the base of an isosceles triangle with a mag 10.5 star 3.5' S at the vertex.

MCG +00-03-033: faint, very small, elongated 3:2 NW-SE, 0.3'x0.2', contains a quasi-stellar brighter nucleus with direct vision. Forms the northern vertex of an isosceles triangle (with sides ~3') with UGC 579 and 583, the two brightest members of AGC 119.

Next group up was the NGC 1016 cluster, located 100' southwest of the challenging double star, Gamma Ceti, a yellow/pale blue pair of mag 3.5/6.5 stars at 2.3". The cluster contains 9 NGC galaxies (993, 1004, 1007, 1008, 1009, 1016, 1019, 1020, 1021) that were discovered by Albert Marth, using a 48-inch f/9.4 fork-mounted reflector (that's right) from Malta and Jean Marie Edouard Stephan (Stephan's Quintet fame) using the Foucalt 31.5-inch silvered glass reflector of the Marseilles Observatory. This cluster was missed entirely by both William and John Herschel which is surprising as there are several reasonably bright galaxies. Here are a few of the better members --

NGC 1016: fairly bright, moderately large, round, 1.5' diameter. Contains a bright 20" core that increases to the center. Located 8' SE of a mag 9.6 star. Brightest and largest member of the cluster.

NGC 1004: fairly faint, fairly small, slightly elongated, 0.5'x0.4', weak concentration. A mag 12 star is attached at the W edge of the halo. Located 13' SW of N1016 on the west side of the cluster.

NGC 1019: fairly faint, moderately large, irregularly round, 1.0'x0.8', low surface brightness. Located 13' SSE of N1016. CGCG 388-080 lies 3.7' N.

IC 241: fairly faint, small, low surface brightness halo surrounding a very small brighter core. Located 8' N of a mag 9.5 star and 14' NW of N1016 in a cluster.

Next I returned to the Pisces-Perseus supercluster, but this time explored the NGC 1129 cluster, the last stop before the Perseus cluster near the apparent eastern terminus of this meandering river of galaxies. William Herschel found the brightest member, NGC 1129 - a massive cD galaxy, but missed its dim companions. Two additional members, NGC 1130 and 1131 were found by Lord Rosse, using his 72- inch speculum reflector at Birr Castle in Ireland but surprisingly he missed a brighter galaxy, MCG +07-07-008, that is nearby. In addition to these 4 galaxies, I picked up 4 additional members for a total of 8. Here's the lowdown on the main players --

NGC 1129: this giant cD galaxy is the brightest in the nearby, X-ray bright cluster WBL 88 = AWM 7 (z = 0.017). Several faint galaxies lie within a few arcminutes including N1130 1.7' NNW and N1131 1.8' SE. A very faint companion (MCG +07-07-003) is embedded at the SW edge of the halo and appears like a short spike jutting out towards the SW.

NGC 1130: faint, very small, elongated ~2:1 SSW-NNE, 0.4'x0.2'. A mag 14 star is attached at the S end. Located in the core of the N1129 cluster just 1.7' NNW of N1129.

NGC 1131: faint, very small, round, 20" diameter, weak even concentration. Located 1.7'' SE of N1129 in the core of the cluster. Brighter MCG +07-07-008 lies 2.7' SE!

MCG +07-07-008: this member of the N1129 group (WBL 88) appeared fairly faint, fairly small, round, 40" diameter. Surprisingly Lord Rosse discovered much fainter N1130 and N1131 in his observation of N1129, but didn't mention this galaxy which is located just 4.4' SE of N1129.

Finally, I ended the evening at Abell Galaxy Cluster 569 in Lynx. There is evidence (see http://tinyurl.com/wox97) that the Pisces- Perseus crosses the Milky Way in Perseus and re-emerges from the veil of dust at AGC 569. If this cluster is connected with the main supercluster, the filament would extend a total length of 500 million light years!

This cluster is dominated by two members, NGC 2329 (discovered by William Herschel) and UGC 3696 and I logged 7 members in total. I'm surprised the Herschels missed the latter galaxy as it is relatively bright (just a couple of tenths of a magnitude fainter than NGC 2329 and too close to miss. Anyways, here's how I recorded the 3 brightest members --

NGC 2329: moderately bright, moderately large, oval 4:3 N-S, 1.2'x0.9', contains a large, brighter core. This galaxy and UGC 3696, located 2.8' NE, are the brightest member of AGC 569. I found 7 members of the cluster at 280x.

UGC 3696: fairly faint, oval 3:2 WSW-ENE, gradually increases to a small bright core. Forms the western vertex of an isosceles triangle with two mag 11-12 stars 1.7' NNE and 1.7' SW. Located 2.8' NE of N2329 in the core of AGC 569. It's strange that neither William or John Herschel, who both observed N2329, failed to pick up this relatively bright galaxy as it is only slightly fainter than N2329.

MCG +08-13-061: this relatively bright MCG galaxy in Abell Galaxy Cluster 569 appeared fairly faint, fairly small, slightly elongated, 0.6'x0.5', small bright core. Located 3.5' SE of a mag 9.3 star.

During the evening one of Bob's neighbors stopped by to chat about astronomy. While driving out, I stopped at his gate and just stared at his 33" f/5 which was still set up in his backyard from the previous night. Looking forward to another visit.

Posted on sf-bay-tac Nov 27, 2006 18:07:28 PT
Converted by report.pm 1.4 Dec 13, 2006 21:50:33 PT

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