This is a high rank event with a dim star; V=12.6 R=11.8 for a W=12.2, which is decently bright for our gear. And, at a convenient time of night on a weekend. The path, however, requires a short travel for good odds. I'm planning on trying from Cabrillo Observatory or maybe the parking area for SeaCliff Beach. Alt=26 in Az 216, in northern Sagittarius. I'm suggesting that KvA not observe from home, but instead drive up to Highland and then east to the wide parking area at the Big Slide, before you get to Camp Loma. The odds there are good; 60%. But at home, only 10%. Kirk and I should coordinate...
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This event was made more difficult by having the target star of mag G=12.7 be blended with another star of G=13.6 only 10" away. This reduced the predicted mag drop from 0.54 to about 0.3. Nevertheless, Kirk and I were both able to get an occultation from PyOTE that satisfied the red bar test. I was deeper into the shadow and had a longer event.
I set up on Mar Monte Rd in La Selva. I originally tried to set up at the usual cul de sac, but two cars with sketchy people were loitering there, so I set up on the north edge of the road, looking towards a clearing between taller trees. I was about 150 yds from some lights and entrance road.
Start 5:15:46 UT
End
5:19:19
Lat 36 56 46.56"
Long 121 50 51.67"
elev 290 ft.
PyOTE results:
magDrop report: percentDrop: 30.8 magDrop: 0.400 +/- 0.048 (0.95 ci)
DNR: 1.95
D time: [05:17:20.4493]
D: 0.6800 containment intervals: {+/- 0.0465} seconds
D: 0.9500 containment intervals: {+/- 0.2738} seconds
D: 0.9973 containment intervals: {+/- 0.9427} seconds
R time: [05:17:24.9872]
R: 0.6800 containment intervals: {+/- 0.0465} seconds
R: 0.9500 containment intervals: {+/- 0.2738} seconds
R: 0.9973 containment intervals: {+/- 0.9427} seconds
Duration (R - D): 4.5379 seconds
Duration: 0.6800 containment intervals: {+/- 0.0949} seconds
Duration: 0.9500 containment intervals: {+/- 0.4188} seconds
Duration: 0.9973 containment intervals: {+/- 1.1835} seconds
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I did two PyOTE analyses; the first ignored the fact I block integrated at 4x; my erroneous report on the verbal tape was "2x". I re-did the analysis Sunday morning Oct 29 9am, and got it right. The timing accuracies degraded, but the times of D and R were the same. It looks to me like there's a decent chance the D was gradual, given the shallow impact angle. Kirk and I were very close to the northern limit and the star hit at a very grazing incidence. My "R" looks much sharper.
Kirk observed from the little road to the water tanks above Cabrillo, just separated from the Hort Road by maybe 20 feet. He observed at 4x setting. He had just a 1.4s occultation vs the 4.5s at my station just a few miles further south. Clearly Kirk was very close to the northern limit.
magDrop report: percentDrop: 27.0 magDrop: 0.342 +/- 0.089 (0.95 ci)
DNR: 2.01
D time: [05:17:21.0910]
D: 0.6800 containment intervals: {+/- 0.0515} seconds
D: 0.9500 containment intervals: {+/- 0.2210} seconds
D: 0.9973 containment intervals: {+/- 0.5689} seconds
R time: [05:17:22.5591]
R: 0.6800 containment intervals: {+/- 0.0515} seconds
R: 0.9500 containment intervals: {+/- 0.2210} seconds
R: 0.9973 containment intervals: {+/- 0.5689} seconds
Duration (R - D): 1.4681 seconds
Duration: 0.6800 containment intervals: {+/- 0.0972} seconds
Duration: 0.9500 containment intervals: {+/- 0.3159} seconds
Duration: 0.9973 containment intervals: {+/- 0.7231} seconds
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Karl got a recording also, from near the Big Slide on Highland way, east of his place.
Long: 121 51 53.1
Lat 37 05 21"
Elev 1792 ft
The recording had some bad time stamps but not around the occultation. There was a seeming dip at the right time, and the dip is only partial just as necessary given the neighbor star which I included in the circular aperture specificiation at 6px instead of the usual best 4px I typically use. However, Karl's Watec is an earlier model and less sensitive than the later v3 models Kirk and I have. The PyOTE reductions fail the false positive test. But the dip's at the right time, and I suspect he got a single integration positive but failed the FP test. I will submit the PyOTE timings and let the auditors make a decision on whether it is real or should be ignored.
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If Karl's lowest point is a single integration occultation, it's at 5:17:23.1 uncorrected. I don't believe Karl's data warrants a "miss", but neither is it a high confidence "occultation". It's in no-man's land!
IOTA report will be submitted, but not done yet.