The Chloris Occultation

May 15/16, 2013

This one was relatively bright, magnitude 10.8, but the sun was at -11 degrees so there would be only a few minutes from the time the stars became visible to find it and get, hopefully, a star trail photo. Becky and Ezra joined me, arriving about 8:30pm and so there wasn't much time before the event - 9:05pm. I had the 12" scope up and running and approximately aimed at the right star field, but no stars were visible in the bright twilight. I gave hurried instructions to Becky... "click off the "track" box and immediately start a 1 minute photo at this time here, on the note sheet I am writing down", and went back out to the 10" so I could try and find the target star. Becky thought that I'd done the "turn-off tracking" on the Gemini red panel already and so she only started an exposure. Of course, it showed an untrailed image. Outdoors, I was able to locate the star with 3 minutes to go. I had the digital recorder going and WWV and the star was pretty easy to see with averted vision, but just barely visible w/o averted vision. I found a spot between the target and another 10th mag star where I could see both easily with averted vision, and waited. Unlike the Hancock occultation 3 weeks earlier, this time I was going to make sure and shout immediately at any hint of a "D", rather than wait for certainty and be too late for a good timing. We had cirrus all afternoon, but the prediction was for clearing skies at 9pm, and this is indeed what happened. There was still a small touch of cirrus over the star and cresent moon 18 deg away, but not enough to cause serious trouble. I shouted a false "D" at 9:05:04, and another "D" at 9:05:08, and this one appears to be valid. The event was short, only 0.5 seconds, so this made for uncertainty. However, Derek Breit not far away in Morgan Hill had a 3.4 second D-R at close to the same time.

A 30 second exposure of the target area, around a half hour later. This is more like what I'd hoped to get.

At 2 1/2, Ezra's learning his first words. "Moon!" is high on the list. Getting a good look through the 10" at craters and lunar mayhem

He's a quick learner in skills too - Loves to go into the POD building and practice putting washers on the bolts.

A budding builder?

I'm teaching him some vital skills - paperwad basketball.

He shoots!

In-and-out - heartbreak! (as veteran Laker announcer Chick Hearn would say if he were here)

He goes in hard for the rebound!

Hoooo!! Slam Dunk!

After a cup 'o Joe (hot chocolate in his case) - the little man is WIRED!

Here's the Excel report sent off to IOTA.

10" pier: Lat=36 59 33.95, Long=-121 55 26.49, elev 211 ft WGS84 on Google Earth

Preliminary Report
Began: 4:02:45 UT
D 4:05:08.04 by voice/WWV, +- 0.3sec, 0.60 RT
R 4:05:08.66 with 0.5s RT, and estimated accuracy +- 0.3 s
End 04:06:00 UT

My short event doesn't make for a typical asteroid profile. However, (IF I was following the right star) the only other alternative was that it was a complete miss. The profile, to fit the simple ellipse plotted, would require me to have had a 3 second occultation after I shouted R, which is not possible.

2nd possibility - I was staring at the star just to the left of the true target. I didn't spend any time re-confirming that i had the target, after an initial relief at finding a star where I expected it would be, relative to the 3 "tripod" ~6th mag stars obvious on the 2 degree chart. Could I have been instead focusing on the neighboring slightly brighter star on the chart? I fixed my gase between those two stars and waited for a "D" and it's possible I suppose that I focused on the wrong star and during the true 2-3 second event, it was immediately after my supposed "R" and I was focusing now totally on the supposed target to see if I got it right. It's now several days later... I'm... Not So Sure any longer!!