Pt. Reyes Summer Kayaking Trip / Delia Occultation

Aug 25-27, 2006

My last weekend trip before classes start. The instigus was the occultation of a bright m=6.9 star with fairly high rank, passing centrally across Pt. Reyes National Seashore, one of my favorite destinations. My plan was to stay at the hostel, kayak on Saturday, buy fresh oysters in the afternoon, do some watercolor painting, and get the occultation early Sunday morning perhaps from Mt. Vision and photograph a dramatic sunrise.

On the drive up, I saw the biggest conflagration of pelicans... ever! Hundreds and hundreds, maybe over a thousand. All in a feeding frenzy just offshore at the beach at Half Moon Bay. Worthy of a photo stop. I arrived at the hostel, met some fellow travellers, fixed a great dinner, and had a cozy evening in the commons room before my first good night's sleep in a while.

Saturday my plan was to put in at Limantour beach and kayak the 5 miles up to Johnson's Oyster Farm. Alas, the high tide was not nearly high enough. Turns out you need a 7+ tide to be able to do that; requires winter high tide conditions to succeed. Plan B was to put in at the marshlands entrance to Tomales Bay. That done, I found after less than half mile that the channel was too shallow to continue. On to Plan C - drive to Inverness and put in at Blue Waters Kayak and head north. This is my second visit to Blue Waters Kayak and I'm impressed with how friendly and helpful they are - whether you're renting gear form them or not. It's a good outfit! It was an incredible paddle - lots of funky old piers and boat houses, colorful lichen covered granite coves, snacking on select seaweeds along the way, lunch at a micro-beach, paddling into small caves, and finally arriving at Hearts Desire Beach at Tomales Bay State Park.

Then on to Johnson's Oyster Farm.

The Delia Occultation.

This was the most favorable asteroid occultation in the last 3 years and a half dozen other local observers planned to go for this one too. The star was m=6.9 in a moonless sky, less than a degree from M35 in Gemini. The problem was fog. The weather forecast was for high pressure to come in and lower the marine layer tops from 2000 ft to more like 1000 ft. Maybe low enough to observe from Mt. Vision inside the National Seashore. After my kayaking I drove into Pt. Reyes Station and Toby's Cafe to hitch onto their WiFi and get the latest. The balloon data showed the marine layer still at 753m which is over 2000 ft. Not good. My plan then was to enjoy the evening at the hostel, and then leave at 2:30am and drive inland along Pt. Reyes Petaluma Rd until leaving the fog behind. Well, after getting to within 8 miles of Petaluma, it was still foggy, and I turned around, headed back to Hwy 1, turned south and drove to the top of Mt. Tamalpais... or as near to the top as I could get. Arriving 35 minutes before the event, I was deep inside the fog. I figured I was done, but there was a little one-lane "for authorized vehicles only" road which was not locked and I figured I'd take it - maybe it might lead higher up the mountain and possible clear skies. It worked! After only a few hundred yards winding around on this service road, it opened up to a panoramic view to the east, and the fog tops on the east side were down a couple hundred feet below me. Set up was quick, as I did not have the video equipment this time. The star was bright and very easy, and a south shift put me near the centerline. Turns out mine was the only successful timings. Everyone else was farther north and saw a miss. Here's the report.

Here's Walt Morgan's summary of the observations...

After re-reading a dozen messages, here's my summary of Delia.

Don Machholz - miss at 33 km north
Ed Morana - miss at 22 km north
Derek Breit - miss near centerline
Noel Lerner - miss ~3 km south
Walt Morgan - miss from 12 km south
Chuck Pullen - sprained ankle, unable to observe from
his planned location, 25 km south
Rick Nolthenius - 1.7 sec from 28 km south
Fred Schumacher - miss from 58 km south

(All of the offsets are approximate, and a couple might even be off a few km.)

The path was predicted as 56 km wide, and the gap between me and Fred was about 46 km. We really had a fairly decent distribution of observers, so it's disappointing that there was only one positive. When it is further considered that Rick seemed to be quite close to the center, and he was only 16 km or so from me, it looks like the path was much narrower than predicted.

But looking at the numbers again, the mid-point between Fred and myself was about 35 km south. It is quite reasonable that Rick would have recorded a near-maximum duration even if he was about 7 km from the actual centerline - Walt Morgan