This is a wide path event by 33km asteroid Kobresia. The nominal eastern limit crosses the Santa Cruz lighthouse and western Scotts Valley. Sunlit Ln is on the same track as already claimed by Liu Yanzhe. The "Berm" is another option, as is the bike crossing. I'd like to sample farther west closer to the centerline since the observers are bunched up against the eastern limit as is. So I will plan to drive up to Davenport.
Alt=27 Az=190 in Scorpius, 3 degrees up/left of Antares.
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Kirk, I, and Liu Yanzhe in SiValley all got long events.
I observed from Roger Way in the Pineridge neighborhood of Bonny Doon, near the water tank - a place that's ideal for most directions in the sky and at 1777 ft elevation. My data is pretty ratty; I could not get good focus, and can see on exam that my settled focus was not quite right, with star images more like small dinner plates than Gaussian distributed. Because of the bright sky and poor seeing and poor focus, I ended up trying to see the faint target at 32x. It was still almost invisible, but I wish I'd settled back at 16x since then I would not have also had to deal with pixel saturation, even on the almost invisible target star, so bright was the full moonlit sky. Still, the event is obvious and passes the FP test easily. But the timings and accuracies don't compare well with Kirk and Liu who were on tracks both slightly closer to the nominal centerline than I was. I used a TME aperture to try to minimize large sky noise. The shape of the TME aperture was a fat fat crescent, due to the stars being out of focus.
Long:
magDrop report: percentDrop: 43.2 magDrop: 0.615 +/- 0.207 (0.95 ci)
DNR: 1.65
D time: [05:40:32.7556]
D: 0.6800 containment intervals: {+/- 0.6671} seconds
D: 0.9500 containment intervals: {+/- 2.5257} seconds
D: 0.9973 containment intervals: {+/- 6.2989} seconds
R time: [05:40:48.1156]
R: 0.6800 containment intervals: {+/- 0.6671} seconds
R: 0.9500 containment intervals: {+/- 2.5257} seconds
R: 0.9973 containment intervals: {+/- 6.2989} seconds
Duration (R-D): 15.3600 seconds
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8/11/24: Using circular aperture did not improve the light curve, nor the timings. The duration given the wide limits I set, still gave a 15s duration. Still, I believe this reduction can be improved, as the duration is 4s longer than the predicted maximum, and 4s longer than Kirk's chord only a few miles away, and with higher S/N and accuracies.
I used the same TME light curve, again used manual time stamp entry before and after the occultation, which gave a valid time stamp result (poor OCR due to very bright sky) but this time I gave it a wider selection for the D and a narrower more obvious place for the R. It improved the timing accuracies, the depth, and also the duration is a better match to Kirk's. Still noisy. Clearly the out of focus stars and very bright sky and 32x were all items that could have been improved upon or anyway were sub-optimal. But the event clearly passes and is real. My D is earlier than Kirk's and R is later, as would be expected since I was closer to the centerline. However, the size of the asteroid inferred is larger than the nominal 10.9s. This below is what I reported to IOTA on 8/12/24.
magDrop report: percentDrop: 50.7 magDrop: 0.768 +/- 0.244 (0.95 ci)
DNR: 1.94
D time: [05:40:32.7557]
D: 0.6800 containment intervals: {+/- 0.4761} seconds
D: 0.9500 containment intervals: {+/- 1.7580} seconds
D: 0.9973 containment intervals: {+/- 4.3583} seconds
R time: [05:40:46.1956]
R: 0.6800 containment intervals: {+/- 0.4761} seconds
R: 0.9500 containment intervals: {+/- 1.7580} seconds
R: 0.9973 containment intervals: {+/- 4.3583} seconds
Duration (R - D): 13.4399 seconds
Duration: 0.6800 containment intervals: {+/- 0.8527} seconds
Duration: 0.9500 containment intervals: {+/- 2.4583} seconds
Duration: 0.9973 containment intervals: {+/- 5.2794} seconds
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Observed at 16x from the Eco Reserve in Bonny Doon
magDrop report: percentDrop: 66.2 magDrop: 1.176 +/- 0.221 (0.95 ci)
DNR: 2.09
D time: [05:40:35.0502]
D: 0.6800 containment intervals: {+/- 0.1374} seconds
D: 0.9500 containment intervals: {+/- 0.4768} seconds
D: 0.9973 containment intervals: {+/- 1.1506} seconds
R time: [05:40:45.1935]
R: 0.6800 containment intervals: {+/- 0.1374} seconds
R: 0.9500 containment intervals: {+/- 0.4768} seconds
R: 0.9973 containment intervals: {+/- 1.1506} seconds
Duration (R - D): 10.1433 seconds
Duration: 0.6800 containment intervals: {+/- 0.2213} seconds
Duration: 0.9500 containment intervals: {+/- 0.6125} seconds
Duration: 0.9973 containment intervals: {+/- 1.3494} seconds
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