This occultation happens during the Astro 8A lab class. If skies are foggy, I'll not be trying it and we'll be indoors. But if it's clear, I will try it from Cabrillo Observatory. Perhaps Kirk can try it from home. The target is only 8 degrees from the first quarter moon, making the sky a bit brighter. Altitude is good, at 61 degrees, the sun is at -12 degrees so we'll have to get on-target efficiently. Odds of a hit are 39%, but aren't much better on the centerline, at 42%.
The 13.9 combined image will drop to 16.1 magnitude (standard, not instrumental mags), so that's 2.2 mags and the image should drop to only 13% of it's unocculted value.
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Results:
Successful recording of an occultation by both Kirk and I. Strange that our first double video successful occultation recording would be on the nominally most difficult event we've yet tried. We both stayed home for this, since even though the rank and odds were good; over 70% odds of a hit in Santa Cruz, based on my past tries, this was going to be so difficult that driving to a site wouldn't have justified the effort. And - I had to stay close to Canvas since I was teaching on-line my Astro 8A class immediately before, and after the event. Taking an hour off was all I wanted to do. But - it worked!
Rick Nolthenius' Results and LiMovie CSV file
Long: 122 01' 55.03", Lat 36 58' 23.23" elev 23 ft
Pyote Final Report and my PyOTE Log file
I had a 2.66 sec occultation (0.275, 0.453, 0.909 as 1-sigma, 2-sigma, 3-sigma) . My observed mag drop was 1.52, but it was pretty noisy and only 5 data points nominally in the occulted zone.
PyOTE raw determined timings were: SNR 2.52
start 3:26:17
D: 3:27:11.230 (0.275, 0.917, 2.298) or 3:27:10.679
R: 3:27:13.899 (0.275, 0.917, 2.298) or 3:27:13.348
end 3:28:38
My LiMovie screen capture |
My full light curve |
Focused on the event. |
Pyote shows, properly, a block integration of 16, offset 12. Or, 1/2 second integrations. Occultation event was measured as 2.66 seconds long |
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Kirk Bender's Results and LiMovie CSV file
Long 122 03' 04.59", Lat 36 57 48.468" Elev 39m
KB Pyote Volga4 Final Report
Kirk had a 3.203 second occultation, longer than mine, but the accuracy of these timings, especially mine, makes that only mildly confident. But 3.203 seconds is longer than the predicted 2.80 seconds, so either we got the long axis of a very oblong asteroid, or it's darker than had been thought. His SNR was 1.73 for his Volga4 csv file.
PyOTE raw determined timings were:
start 3:26:03
D: 3:27:11.262 (.204, .956, 2.26)
and final reduced true time of 3:27:10.978
R: 3:27:14.465 (.204, .956, 2.26) and final reduced true time of 3:27:14.181
end 3:28:07
Volga3, on this row of images: Screen capture of Kirk's LiMovie analysis. The photometry annuli are not on the stars, but they wander during the 2 minutes of data taking and when you "rewind", the circles remain where they were. Not a problem, just confusing. |
Kirk's full light curve. The target is at bottom, in blue. |
Zoomed in on the event |
PyOTE found blocksize 8, offset 1. My chosen D and R look range. |
PyOTE's solution for the D, R. His light curve is cleaner than mine, with identical equipment, and yet using only half the integration time. Why is that? |
histogram of the 100 solutions of the occultation duration |
His wider photometry circles version: Volga4; the LiMovie csv file reduced gave exactly the same D, R times, very similar but slightly better error bars at 2-sigma and 3-sigma...
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