This is a bright enough event to get a solid positive if inside the path. The path goes across Karl, but misses us in Santa Cruz. I put down a market at BD airfield on Sunlit Lane. The Church on Bonny Doon Rd off Pine Flat, is another decent spot. Those 3 would cover the area near the centerline and halfway to the southern limit.
Alt=33, Az=185 in Sagittarius
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I drove to Sunlit lane. I had a bit of trouble because the field had so many stars I mis-read the RA as being at 19h instead of proper 18h. I recovered from that in time, and did a successful GoTo the target, but I didn't have time to reduce the integration from the GoTo usual 8x, to a more proper 2x for a star this bright. It looked like a miss on the computer screen.
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Ref star, showing the false drops near the end of the recording |
An obvious miss on this bright star |
Looks like a miss for me for 1999 VK37, 1x from Bonny Doon church, no apparent event. It looked doable at 1x, and I can see the target consistently on playback, but the target level is close to background. The seeing wasn't great, and I turned down the gamma to see the target better, so both target and background are noisy. I probably should have gone with 2x and still have had enough integrations if it was a positive. The target was close to another star, so I used small size 11 apertures. The PyOTE detectability tool reported that with my data an event as short as 0.35s was likely detectable, but maximum predicted duration was 0.32s. The PyOTE help says it's a no-observation if the shortest detectable event from the tool is 1.5x predicted, presumably to allow some leeway for the prediction, so according to that mine is not a no-observation. So a miss or undetectable.
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The only suspicious event possibility I see, is about 6:18:19.7 or so, with several consecutive points at ~0. |
Planned to observe from Watertruck Turn 11:08:19 1999 VK37 from rock, clear, dark, ok seeing, no wind, used 2X. Moisture level rising, fog come in moments after we broke down, No noticeable blink. Processing: Pretty obvious miss. A dip 9 seconds after the predicted time looked possible, but PyOte found a less likely looking event about a half minute before. I declare it a miss!
Revised notes from Karl: July 30 (31) 11:08:19 1999 VK37 from rock, clear, dark, ok seeing, no wind, used 2X. Moisture level rising, fog come in moments after we broke down, No noticeable blink. Processing: Pretty obvious miss. A dip 9 seconds after the predicted time looked possible, but PyOte found a less likely looking event about a half minute before. I declare it a miss! -Rick asked me to re-process: used different Ref star=better smoothing. Pyote suggested event ~7 seconds after predicted, bu no confidence. Claimed miss, but uncertain.
RN: Since the target even on it's bigger long dips, never went close to zero, this looks like a miss but with poor calibration. The light curve looks like it has an event, but the light curve of the target is not flat anywhere, and the "event" does not go to zero. It would be good to see "sky" plotteed as well. The constant varying in the target suggests not properly calibrated, apparently there was very different obscuration happening over the target vs over the ref star. Was the ref star rather far away from target, and was there fog or clouds that were fine-scale and so they were not affecting the ref star and the target star both near the same times? If so, then it's essential to use a ref star that is much closer to your target star. Even if the ref star is not the optimum brightness we'd prefer. And it's essential to also optimize the x-axis (the time offset) when minimizing the flatness metric in PyOTE.
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The target light level stays above zero, which suggests a miss. But the "sky" level is not plotted and should be. |
