Outstanding Night at Dinosaur Point

Mark Wagner

Saturday April 18th was one of those days the astronomy gods smiled on. You can't tell when you'll get one. Sometimes there can be an entire observing season full of them. Then they can disappear for years. A friend once equated observing to skiing, saying conditions make all the difference. A great day skiing is memorable, like a great one observing. Saturday night was a very good one. The combination of very good seeing, transparency, little wind and warm temps made it about perfect.

Even the drive there, for those of us who beat the accident on 152 east, was easy, and beautiful. This has to be the prettiest time of year to drive out of the city. The hills are green, with yellow mustard and orange California Poppies. The spots that are not green are either a rusty red ochre or speckled granite. Pacheco Pass is an amazing place.

The turn to Dinosaur Point comes up fast. It is easy to miss, almost directly behind the sign. The road passes the entrance to Pacheco State Park, which was the old Rancho San Luis Ganzaga, back in the days of the California gold rush. The old stagecoach road can be seen down in a gully just past the entrance gate. The observing site is a large paved parking lot just above the boat launch at San Luis Reservoir. Literally hundreds of vehicles could park there.

The turnout was very good, a combination of lots of long time observing friends, with a good number of new attendees as well. We were all in for a treat.

The Zodiacal Light was huge. It was obvious well before dark. The seeing was never poor. It was excellent often during the night, with periods of slight softening. Saturn was easily winner of the beauty contest. Incredible, especially in a few Astrophysics refractors (5" and 6"), as well as a great homemade 10" Mak-Newtonian. In my 18" f/4.5 Dob, some of the real showstopper targets were at their best. M51 was showing spiral structure deep down into its core. The arms were etched at time. M94 too was showing tons of detail, big sweeping arms, an intense big nucleus, spiral structure in the outer core... the big globulars were at their best.

It was hard to go wrong. The only improvement I can imagine is to not have the seeing soften at all during the night. I'll put my order in now, for new moon June.

I didn't just look at big and bright stuff for the night. I was working the edges too. Probably the most challenging views of the night were Arp 204 and Hickson 66. Others were just plain interesting or fun, like NGC 5308, NGC 5322, NGC 5023 and NGC 5103. I finished the night sharing views of Copeland's Septet, with the entire group showing nicely.

This was truly a nice to enjoy being at the eyepiece, under a great sky, with your friends. More like this!

Even the drive home was easy. I was home by 3.

Here are my observing notes for the night. I didn't push it, enjoying the experience, looking through my friend's telescopes and sharing views through mine.

Arp 204 Cam GX 0.8'x0.3' 16.4 13 22 45 84 30 28 PGC46811
Arp 204 Cam GX 2.5'x0.5' 15.6 13 22 49 84 30 08 UGC 08454
18" 7mm - UGC 8454 is dim and elongated 3x1 E/W with no notable detail. Even brightness across. PGC 46811 lies to the W and is fleeting, coming in and out as a slight small amorphous brightening.

Arp 104 UMa GX 2.9'x1.6' 12.3 13 32 10 62 45 53 NGC 5218
18" 7mm elongated E/W and appears disrupted. Roundish, like it may be a spiral. Very dim star possibly embedded in E end. E end appears to hook N, W end appears to hook S. Even brightness throughout, no core visible.

Arp 104 UMa GX 2.4'x1.8' 13.6P 13 32 07 62 42 01 NGC 5216
18" 7mm about 7' S of NGC 5218. Appears round with bright core and stellar dim nucleus. Extended halo surround core but is quite dim.

Arp 238 UMa GX 0.9'x0.7' 14.4 13 15 29 62 07 27 UGC 08335
Arp 238 UMa GX 1.0'x0.6' 15.3 13 15 35 62 07 27 MCG+10-19-57
18" 7mm - small dim pair form this Arp. E/W to each other, with a pair of stars in identical orientation just to their N, forming an easy parallelogram. Eastern member seems brighter.

N5308 UMa GX 3.7'x0.6' 12.3B 13 47 00 60 58 23
18" 7mm - fairly bright and gorgeous spindle. Extremely bright stellar nucleus, maybe Seyfert galaxy. Elongated core around nucleus. Orientated SW/NE with hints of a dust lane along the 4'x0.5' size. Dust lane if there is on NW side of nucleus.

NGC5322 UMa GX 5.9'x3.8' 11.1B 13 49 47 60 11 26
18" 7mm - elongated E/W and about 2'x1'. Brighter core inside dimmer speckly halo, makes it look somewhat like a globular cluster. Nucleus is almost stellar.

N5204 UMa GX 5.0'x3.0' 11.7B 13 29 36 58 25 09
18" 7mm - elongated N/S about 3.5'x1.0'. Soft western edge, hard E edge. Even brightness across object, but hints of mottling and a slightly brighter core barely shows.

HGC066A UMa GX5 0.5'x0.4' 15.8B 13 38 38 57 18 44 MCG +10-19-104 PGC48226
18" 7mm - Hickson 66 is SSE of the nearby MCG 10-19-103, and appears clumpy with a ENE/WSW orientation. Could be just one object elongated, but appears to be more than one.

Arp 239 UMa GX 0.7'x0.4' 15.0 13 41 43 55 40 23 NGC 5279
18" 7mm - very small with some possible NW/SE elongation. This Arp pair also has pairs UGC 8671 and MCG 9-22-94. Arp 239 UMa GX 0.8'x0.6' 13.5 13 41 39 55 40 12 NGC 5278
18" 7mm - elongated E/W and fairly even brightness. Fairly bright.

NGC5195 CVn GX 5.8'x4.6' 10.5B 13 29 58 47 16 21
18" 7mm - bright nearly stellar core with a dark lane bisecting the galaxy NW/SE of the core, obscuring that side of the galaxy. W side of galaxy is round and bright but has a brighter bar NW/SE along the edge of the dark lane. Very interesting object. M51 CVn GX 10.3'x8.1' 9.0B 13 29 53 47 11 48 Arp 85
18" 7mm - incredible detail under very steady seeing. Main two arms are almost etched. Core has a bright stellar nucleus, with spiral structure within the core into the nucleus.

NGC4800 CVn GX 1.5'x1.1' 12.3B 12 54 37 46 31 50
18" 7mm - spiral with a dim pinpoint stellar core, 3'x2' elongated N/S. Bright core around the nucleus, with a large dimmer envelope around the core.

N5023 CVn GX 6.7'x0.7' 12.9B 13 12 11 44 02 20
18" 7mm - elongated 7'x1.5' slightly W of N/S. Dim, pretty brightness across object, but hint of bisecting dust lane and several areas that appear to be brighter HII regions.

N5103 CVn GX 1.4'x0.9' 13.6P 13 20 30 43 05 02
18" 7mm - small, in beautiful setting at the end of a small chain of three other dim stars next to a bright star. Elongated NW/SE, in an oval. Appears to have a bright bar or spindle inside the halo. Very bright stellar core. Pretty object.

M63 CVn GX 13.7'x7.3' 9.3B 13 15 49 42 02 06
18" 7mm - very bright. Elongated 5x2 WWNW/EESE. Very bright pinpoint stellar nucleus surrounded by a large bright core about 4'x1.5'. Extensions off the core gradually dim, and have some hints of visible spiral structure (dark lanes). Excellent example of a spiral galaxy.

M94 CVn GX 14.3'x12.1' 9.0B 12 50 53 41 07 10
18" 7mm - very bright, very large. Inner core is solidly bright and large, containing a pinpoint small nucleus. An outer core is distinct from the inner core, and appears somewhat mottled, possibly by tightly wound spiral arms. Two large sweeping spiral arms come out of the bright second core at the N and S and wrap around the galaxy, N to the W and around, S to the E and around. The bright outer core in moments of great seeing do show spiral structure and dark lanes. Galaxy outer core is elongated slightly NW/SE. What an object!

Observing Reports Observing Sites GSSP 2010, July 10 - 14
Frosty Acres Ranch
Adin, CA

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