Here's my long observing report. The short version is that turbulence made the view less than ideal and we had to pack up before the third shadow appeared. I didn't even try to get any pics. I had better luck with the March 28/29, 2004 triple shadow transit, which I saw in its entirety.
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Our winters in Fresno, CA, are often plagued by Tule Fog, which sometimes stays on the deck for days on end and sometimes rises to about 1000' AGL during the day, then drops to the ground at night. By Wednesday, we had endured two weeks of the latter, but around noon on Thursday, the skies began to clear. By sunset, the skies were completely clear. After dinner, I took my 20x80 binos out to look at Comet Loveyjoy, M42, etc. I also checked the weather report, which predicted nearly three days of 100% clear weather. So, I quickly set up an impromptu star party at a local park I sometimes use to see the triple shadow transit, the comet, and whatever else we chose to look at. Several club members were going to join me along with a bunch of people I know who wanted to see this.
Then Mother Nature took over. Friday never cleared…well, for about 10 minutes around 5 PM, cloud cover was down to 95% and Moon was visible around 6:30 PM. So, I had to cancel the star party and switch to Plan B. Plan B was to head for the hills. My Plan B observing location was the Big Stump parking lot in Kings Canyon National Park (36°43'15.30"N, 118°58'15.40"W, 6300' elev). It's about 60 miles and 1 hr 10 min from my house and on a winter day/night like this temperatures can actually exceed those on the floor of the San Joaquin Valley. In our case, Big Stump was only a couple degrees cooler over the course of our observing session.
Here's the detailed observing report I passed along to my friends:
The skies at Big Stump were clear and transparent. However, the atmosphere was somewhat turbulent to the east, looking over the mountains. This affected our view of the shadow transits, which I will describe below.
The temperature at Big Stump was only a couple degrees cooler than in Fresno, so that wasn't a big problem. When we arrived, it was 45°F and the humidity was 20%. We we left to come home, it was 36°F and the humidity was 25%. We passed through a thick high fog layer heading up (between about 1500' and 2500'), but only a very thin layer at about 1500' coming home. For observing, we had my 8" telescope (Celestron CPC-800) and 10x50 and 20x80 binoculars.
To the west, looking over the valley's inversion layer, the air was rock solid. The air was similarly steady to the north and in a 90° (or so) cone around the zenith. The stars in these directions did not twinkle. The Pleaides (M45) was steady and very bright. With the unaided eye, I could resolve the cluster's 6 brightest stars. Younger eyes could probably see a few more. In the telescope I could see the brightest parts of the nebula that this open cluster is passing through. Comet Lovejoy showed a tail, which I had been unable to see from the valley floor.
The Orion Nebula (M42/43) was spectacular, and that was without putting the OIII filter on the eyepiece. This is my first time observing Orion from the mountains and I was blown away by its size and brightness. Usually, I see the Orion Nebula from my backyard or from Eastman Lake, and it's very nice, but nothing like this. The amount of detail was phenomenal. The embedded Trapezium star cluster was not quite steady, but that's because this part of Orion was on the transition from rock solid overhead skies to turbulent southern skies. For example, the bright star Rigel (a little lower in Orion) twinkled and the brighter star Sirius (a little lower in Canis Major) looked like it was boiling. I had hoped to see Sirius' white dwarf companion for the first time, but the skies did not permit it.
Now to Jupiter…We began observing at 7:50 PM, or 40 minutes after Callisto's shadow started moving across the disk of Jupiter. Due to the turbulence in the lower atmosphere (Jupiter was then only 17° above the horizon), I couldn't see the shadow at first. Jupiter subtends 45 arcseconds and Callisto and its shadow each subtend 1.7 arcsec. My telescope has a theoretical resolving limit (Dawes Limit) of 0.57 arcsec, so under steady skies, it would not have been a problem. In fact, when I saw the March 28/29, 2004 triple shadow transit, it was with a 5" telescope (Dawes = 0.91 arcsec) from my backyard…but those skies were rock solid.
So, for about 20 minutes, I tracked down other objects and showed them to Debi and my 6-year-old granddaughter, Abi (Jupiter is Abi's favorite planet, which is one reason she came with us). At 8:10 PM, Jupiter had risen to 21° above the horizon and I could finally see Callisto's shadow. It remained visible the rest of the time we were there. For planetary observing, I prefer to use my 8 mm eyepiece (254x), but due to the turbulence, my 13 mm eyepiece (156x) provided the best compromise between magnifying Jupiter and magnifying the turbulence (e.g. the turbulence was not really noticeable in my 27 mm eyepiece (75x) but neither were the shadows).
Io and its shadow subtend 1.1 arcsec, but this was enough of a difference from Callisto to make Io's shadow a hit-or-miss proposition the rest of the night. I wasn't able to see Io's shadow early in its passage because Jupiter's limb is darker than the middle and the lack of contrast hurt. I first saw Io's shadow at about the same time that Io itself began its transit, or about 9:00 PM. Abi saw Io right off the limb of Jupiter and she liked that. I saw the combined Callisto/Io shadow about 9:50 PM, right before we decided to pack up. We took our last look at 10:10 PM. We decided to leave before Europa's shadow made an appearance because it was getting colder, the turbulence compromised the view, and we had a 6-year-old astronomer to get home for bed.
BTW, in an 8" telescope, all four of Jupiter's big moon are seen as little disks, not pinpoints. Ganymede (1.7 arcsec) was especially impressive.
Since the views of Jupiter were not as pleasing as I had hoped, I spent quite a bit of time tracking down things I had not seen before, such as the Flame Nebula, the small background open cluster next to the large open cluster M35, Hind's Crimson Star (a carbon star, and the reddest star in our skies…although it is more deep orange than red), the Heart Nebula and its neighbor the Soul Nebula (the latter was easier to see and its embedded star cluster is quite nice), NGC 2362, which is a triangular shaped open star cluster with a bright star in the middle and a diffuse background that hints at other stars, etc, etc, etc.
