Monday, December 3, 2007 - Dinosaur Point

Albert Highe

However, it looked like we might get another chance to observe Monday night. A severe storm passed to the north of us, but the edge of the front seemed to bisect the Bay Area, leaving Dino in the clear. The CSC and satellite images looked promising, clouds being pushed north by a high pressure cell to the south. Moreover, temperatures were predicted to be warmer than this past weekend. During the Winter, observing opportunities are often rare, but sometimes opportunity knocks more than once.

I left home just after 2PM in order to avoid much of the traffic. I had a pleasant, relaxing drive down. Clouds completely covered Redwood City when I left, but, as I drove south, clouds gave way to mostly blue skies threaded with high cirrus. The temperature reached 71°F.

After stopping for gas and food, I arrived at Dino just before 4PM. Wind on the lake was about 5mph and windmills on the nearby hills turned lazily. I felt no wind in the parking lot, and the temperature was 68°F.

It took only a couple of minutes to set up the 13" f/4.5 "blue" scope that had made the trip to Australia last month. The OTA is short enough to fit in my van fully assembled, so it now serves as my "grab-and-go" scope - ideal for extending observing time that would normally be eaten up tearing down a larger scope at the end of the night.

By 5:30PM, stars started popping out. I collimated the scope and aligned the finders. The temperature had dropped to 53°F with a relative humidity of 57%. No wind.

At 6:15PM, Ranger Betty stopped by, thoughtfully turning off her head lights, and drove up with her parking lights on. We chatted while I showed her the comet, Albireo, M57, and M31. The cirrus was clearing nicely, leaving only a bank of clouds along the horizon to the north. I got down to business after she left.

Conditions were very enjoyable - relatively warm for December. The temperature hovered around 50F most of the night, finally dipping to 48°F just after Midnight. In addition, it was dry - % relative humidity never rose higher than the 70's. There never was any wind. Seeing was very good all night, above average for Dino. The double-double was easily split early in the evening, and the Trapezium showed six steady stars later. Even Sirius, low in the sky, barely twinkled. I observed with the 7mm Nagler Type 6 (212X, 1.5 mm exit pupil) most of the night.

I observed in solitude and silence, starting in Cetus. During the early evening, bands of cirrus would periodically peel away from the edge of the front, and pass over Dino in waves, moving in from the northwest. During this time, transparency would diminish. Rather than jump around, I patiently waited until each narrow band passed, and transparency returned.

Just prior to Andrew Pierce's arrival a little past 8PM, the sky had gotten worse. High cirrus drew a thin gauze across the sky. Stars were visible, but observing faint fuzzies was greatly hampered. It looked like it might be a short night.

However, a small hole to the south persisted, and its size grew during the remainder of the night. By the time we left at 12:30AM, most of the sky was once again clear except for the band of clouds along the northern horizon. An average of four SQM readings (Kingsley method) yielded 20.95.

It was a shame to leave such a nice sky. I considered staying later. But after six hours of observing, I was fading. And I still had to drive home. If a bed were close by, I would have pushed myself to do more.

The variable transparency slowed me down, but it wasn't annoying. It was an enjoyable, productive night. I logged observations for over 60 objects, most of them observed for the first time. Below are a few highlights.

Cetus

Arp 127, a close pair of galaxies: NGC 191 and IC 1563.

NGC 191 appears as a roughly circular halo about 1' across, with a somewhat brighter small core.

IC 1563 appears as a pointed-tip oval with a somewhat brighter, small core. It appears about 0.2' x 0.5' and lies 0.7' south of N191. Its long axis points toward N191, but not directly at its core. The tip of IC1563 appears to just touch the edge of N191's halo. Can hold both steadily with averted vision.

NGC 246 - I hadn't observed this planetary nebula in years. At 212X, it was readily apparent as a roughly circular band approximately 3.5' wide that encompassed four bright stars. The western edge was notably brighter. More careful study with a 9mm Nagler T6 (165X) and an OIII filter, revealed more structure. A ring of undulating brightness forms a partial circle of about 270°. The partial ring opens along the "back end," towards the east. Fainter mottled nebulosity fills the interior of the ring. In addition, the northeastern end of the open ring brightens, and widens inward, into a delta-shaped fan.

NGC 988

George Feliz mentioned he observed this object at Dino on Saturday. Even in good conditions, the overlapping bright 7th magnitude star makes observing this large 11th magnitude, low surface brightness galaxy challenging. With passing cirrus, a nebulous haze often surrounded the bright star. However, during clearer conditions, and using averted vision, I steadily could see a uniform, low surface brightness nebulous tongue, approximately 1'x2.5', stretching ESE of the star.

NGC 1010

NGC 1011

NGC 1017

Close trio of very small galaxies. N1010 and N1011 are the closer pair, N1011 lying about 1.5' NE of N1010. Both appear circular, but N1010 is somewhat larger and brighter. I could hold each steadily with averted vision. N1017 was more elusive, lying 2.7' east of N1011. It appeared smaller and maybe slightly oval. Eventually I could hold it 75% of the time with averted vision.

Eridanus

HCG 23

I observed four galaxies in this Hickson Compact Group. Without a DSS image to guide me (and/or greater aperture), I missed the fifth and faintest member.

NGC 1214 - Small oval with somewhat brighter small core. Appears to be the brightest of the group. Could just hold the brighter core with direct vision.

NGC 1215 - Lies nearly 3/5ths along a line 7' long, running NW to SE between N1214 and N1216. Appears as very small oval or circular galaxy with somewhat brighter small core. Could just hold the brighter core with direct vision.

NGC 1216 - Appears as very small, more elongated oval. Also has a smaller and brighter core that is just visible with direct vision.

MCG-2-8-50 - Very small oval 5' south of N1214. I could eventually hold 50% of the time with averted vision.

Wish more of you could have joined us.

Albert