This event is short, only 0.4s, making it difficult. But bright enough that with clear skies we can try it at 2x and get a do-able positive. The rank is nominally good, and Cabrillo Observatory is near the centerline. Kirk and Karl are also inside the path. Fog is a possible problem, but perhaps not at the early time of 7:27pm. The sun is -12 and the moon is 92% and so sky brightness will be an issue. The target is in the rich starfield of Sagittarius, just to the right of the 'spout of the teapot'.
Alt=19, Az=207
I will have to be with my Astro 8A students and also hoping to see the comet. I'm not sure whether we'll be at the Observatory or not. My second choice would be on Rodeo Gulch at the top, although parking that many cars there may be a problem.
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I observed under clear skies at the top of Horticulture access road, just before the deer fence into the Horticulture main grounds, and uphill of the little road to the water tank and cell tower. My data looks almost as steady as Kirk Bender's. He had an obvious and solid 0.33s occultation. Mine looks like a miss, but I can't rule out a possible single integration drop or partial drop, though no hint is in my data.. It will be filed as a "miss" with a warning it might have a short event, however no short event is even hinted at during the predicted occultation omoment. It looks like a path shift, since I was near the centerline, and the path shifted north towards Kirk Bender, at "the Berm". The event was on-time, so my drawn square wave light curve is positioned correctly or perhaps a square wave interval to the right would be more likely my event time. The event time advanced going west to east, so an event for me would be about 0.4s later than for Kirk (estimated, by putting down test icons on the OWc map to get the predicted time. For my actual position and for Kirk's, the center time was the same as rounded to the nearest second as OWc does).
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My back-of-envelope estimate of the true event time for me, given Kirk's clear positive, is now not at the vertical gold bar, but instead at the beginning of the suspicious 3-integration drop to ~zero about frame 2892. I need to re-analyze my data with more attention to absolute maximizing of significance. Maybe I had a positive after all? |
This square wave is too early to be proper. I must re-do this. |
The square wave above is then too early to be proper. I will re-do analysis before making a re-evaluation of my light curve (as of Sunday Nov 3 at 11:32am PST. It may be that the dip seen after the vertical gold line in panel #3 above is the actual event time. I will re-do with TME apertures and check. For now, )
2nd Analysis: TME analysis.
Use ref1 as the reference star...
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Kirk Bender's solid positive puts a constraint. I used OWc's map and progressive test icon positions to determine how the predicted time changed with path longitude position, and determined that my position should have had an event ~0.4s later than Kirk. That means my "event" if it happened would center at UT second 46.57, There's a dip, is it too late?? |
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Calibration did not help resolve this. My light curve remains consistent with a miss, or a positive, depending on ref star and proper calibration and site offset from KB. |
3rd Analysis using the Same TME PyMovie Data
Using same TME data but now using ref2 star as the calibration, and by telling PyOTE to focus on the obvious dip to zero dip slightly later than I expect based on KB's data, it does detect a 0.32s event, but the FP test passes at only the 1-sigma level. I conclude that it's not possible to judge with confidence whether this event is real. It happens at about the expected time, the rank of the event is good, and I was closer to the centerline than Kirk, which argues in favor of "real", but it happens perhaps a tenth of a second or so later than my back/envelope calcs of when it should occur based on Kirk's solid timings.
I will let the auditors make their judgment of its reality perhaps after a sky plane is done. I will file it as a positive now, with caveats.
magDrop report: percentDrop: 65.7 magDrop: 1.163 +/- 1.043 (0.95 ci)
DNR: 2.06
D time: [02:27:46.5908]
D: 0.6800 containment intervals: {+/- 0.0515} seconds
D: 0.9500 containment intervals: {+/- 0.1984} seconds
D: 0.9973 containment intervals: {+/- 0.5051} seconds
R time: [02:27:46.9108]
R: 0.6800 containment intervals: {+/- 0.0515} seconds
R: 0.9500 containment intervals: {+/- 0.1984} seconds
R: 0.9973 containment intervals: {+/- 0.5051} seconds
Duration (R - D): 0.3200 seconds
Duration: 0.6800 containment intervals: {+/- 0.0907} seconds
Duration: 0.9500 containment intervals: {+/- 0.2792} seconds
Duration: 0.9973 containment intervals: {+/- 0.6150} seconds
PyOTE did find an event, of low confidence. It did drop to zero at one point. |
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I got a distinct .3 sec event for 2002 KN8, 4x at the Berm, right at predicted time. Used TME aperture in PyMovie.
magDrop report: percentDrop: 100.0 (magDrop cannot be calculated because A < 0)
DNR: 3.45
D time: [02:27:46.0022]
D: 0.6800 containment intervals: {+/- 0.0198} seconds
D: 0.9500 containment intervals: {+/- 0.0514} seconds
D: 0.9973 containment intervals: {+/- 0.1085} seconds
R time: [02:27:46.3358]
R: 0.6800 containment intervals: {+/- 0.0198} seconds
R: 0.9500 containment intervals: {+/- 0.0514} seconds
R: 0.9973 containment intervals: {+/- 0.1085} seconds
Duration (R - D): 0.3336 seconds
Duration: 0.6800 containment intervals: {+/- 0.0293} seconds
Duration: 0.9500 containment intervals: {+/- 0.0673} seconds
Duration: 0.9973 containment intervals: {+/- 0.1300} seconds
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