Saturday 3/1/03 at Dino Point.

by David Kingsley


I did not decide where to go observing Saturday night until I was driving down 101 around 5:30 pm. The Coe ridge above Morgan Hill looked nice and clear. However, NWS forecasts had mentioned possible strong winds in the East Bay Hills, and the flags and trees in Morgan Hill were flapping and swaying ominously at the East Dunne exit. I have always liked both the setting and horizons at Coe. However I got blown out of an observing session there in January, and have read several other reports since of people running into troublesome breeze or wind over the last several weeks. (Mark Wagner on February 1st, Marek Chichanski on Feb 22). Given the strong breeze in Morgan Hill, I decided to keep driving further south Saturday night. (It sounds like people who went to Coe ended up with a good night on Saturday. Jeff Crilly did mention it was "a tad windy" though, and he ended up observing in the lee of vehicle to help block the breeze)

I had a good view of Fremont Peak as I continued down 101. The radio towers at the top were just barely peaking out of a cloud band that covered the top third of the mountain. Depending on how the cloud band moved over the night, that could mean either nice dark conditions just above the clouds, or sopping wet conditions at the top. I have had several excellent viewing sessions at Fremont Peak over the last several months, and have found that wind there is usually less of a problem than at Coe. However, the clouds visible near the top on Saturday made it look like there was nearly an equal chance of a great observing night or a cold wet bath at the Peak. (From Peter Natscher's later report, the clouds I saw near the top the Peak must have been part of the mountain clouds that overtook the top around sunset, but then retreated, leaving fairly clear skies but somewhat moist conditions for most of the night).

Based on the clouds visible near the Peak, as I approached the 152 exit I made the last minute decision to head further inland to Dinosaur Point. I had called the "current wind conditions" phone number for the Dino Point area before I left in the afternoon. This is a handy recorded message that summarizes current wind speeds and winds over the last several hours(209-826-9019). I was encouraged to hear at mid afternoon on Saturday that winds had been dead calm there during most of the day (1 to 3 mph). There were some scattered low clouds around as I drove towards Pacheco Pass. I arrived in the Dino Point parking lot shortly after 6 pm and joined about 8 other observers already set up in the wide open parking lot next to the Lake. There was almost no wind at all as I set up. Most of the low clouds hanging overhead cleared out shortly after it began to get dark, just as Denny promised they would. We had clear skies and pretty good conditions most of the night, with temperatures in the mid 40s, and humidity climbing from the 70s to the mid 80s. Light dew formed on exposed surfaces during the early evening. However, it was not severe enough to inhibit observing, and declined even further when a breeze picked up around 10:30 or 11 pm.

Although skies were reasonably dark, the transparency and seeing were not as good as I have seen in the past from this location. I did not do any naked eye limiting magnitude estimates Saturday night. However, nearly every observing session, I try to track down some targets that are at the ragged edge of what I can see with my 14.5 inch scope. The limiting magnitude through the scope depends on a combination of both good transparency and good seeing. On Saturday, the limiting magnitude in my 14.5 inch Dob was probably around 15.3 or so when hunting faint stellar objects, compared to 16.1-16.2 or so from typical Bay Area sites on a good dark night, and 16.7 from a really good dark steady night under ideal Bumpass-Hell like conditions. The seeing seemed to get more wobbly Saturday as the night wore on. Although some observers started off using magnifications up to 400 or more on Jupiter early in the evening, by 11 pm there was lots of visible twinkle to naked eye stars all over the sky, and high power views of both planets and star fields had obvious shimmer.

Sadly, the new security lights on the dam to the southeast now detract somewhat from one of my favorite observing locations in the South Bay area. Marek moved his vehicle at one point to try to block any direct line of sight to these lights from his position seated at the telescope. Above the short row of lights there was a noticeable new light dome extending at least 30 degrees up in the sky towards the east-southeast. It is only a problem in one direction, and was probably worse on Saturday because of humidity in the air. Although I think the rest of the sky at Dino is still probably darker than most other Bay Area locations, it is a real shame that you now have to think about lights and observing direction when you set up your scope and vehicle at Dino Point.

Saturday was my first time out observing since installing an Orion erect image 9x50 finder on my 14.5 inch Starmaster Dob last week. I really enjoyed having easy access to an upright, nonreversed image for scanning the skies and homing in on targets. I had removed the telrad that usually sits on the upper tub assembly to make way for the 9x50 finder. I found that an eye full of stars in the finder was so much more useful than the 1X view through the Telrad that I doubt the Telrad will ever go back on the scope.

I also set up a heavy-duty adjustable music stand on Saturday night to serve as a portable observing stand for notes and charts near the eyepiece. I have found this to be much more useful than a fixed height table, because the stand is easy to pick and move around during an observing session, and to adjust in both height and angle to suit particular targets. I was concerned that it may be too light and tippy to hold what I needed, but this particular model has enough weight and spread at the base that it has held lots of charts and books well, including an open volume of the Millenium Star Atlas. The Axman heavy-duty folding music stand is relatively cheap at around $.35. Check out http://www.musiciansfriend.com/srs7/sid=030303234153171066166090341440/search/g=other/detail/base_id/40693 for more information and a picture.

I saw a number of objects during a fun but relatively short night that included one more extragalactic glob in M31, and a visit to the infant star FU Ori just sputtering to life in dark nebula B35 in Orion (see Steve and Jane's reports from last weekend). Having seen one of the youngest stars in our own galaxy, I then went hunting for the most ancient light I had ever seen visually in a telescope. APM08279+5255 is a distant quasar in Lynx. Although fainter visually than the often observed quasar 3C273, APM08279+5255 has a much higher intrinsic luminosity. It's redshift of 3.87 is more than 24 times that of 3C273 at z= 0.16. APM08279+5255 therefore pushes the limit of the universe about as far back as you can observe visually with a midsize telescope. At an estimated distance of 11 billion light years, this tiny mag 15.2 spec of light offers a rare chance to peer back all the way back to the infancy of our own universe. APM was the subject of an Astronomy Picture of the Day back in 1998. For further information on one of "the brightest objects in the universe" see: http://apod.gsfc.nasa.gov/apod/ap980818.html.

When the seeing got softer after 10:30 pm or so, I switched from faint stellar targets to big bright galaxies and open clusters. It was great fun to hop around from one object to the next, using the 9x50 finder to put the scope dead on a range of Messier and NGC objects. The wind began to pick up as the night went on, reducing any problem with dew, but also adding some jitter to the scope. I packed up before midnight, and drove out under clear but twinkly skies after four hours of observing.