The Occultation of a 14.1 Star by Pompeja

Aug 6, 2023 at 10:19:02pm

This is nominally a high rank event, but the RUWE is 2.15, so the astrometry of the target star is not good. Odds of a hit anywhere in the Santa Cruz area should be considered roughly 50/50. The star will fade from 13.0 to 13.55 for about 30 seconds. Should be straightforward in a dark sky with no moon.

Results:

Richard Nolthenius

I didn't want to sit on Kirk's track line, which anywhere on Empire Grade would have done, so I drove to the top of the Santa Cruz Mtns and Summit Rd. But the target was far enough west that the Mtn Charlie monument turnout was too in the trees to use. I drove a 1000 yards down Mtn Charlie and found a spot that was quiet, dark and a perfect view of Sagittarius, and set up there. I started taping 4 minutes before the event and kept going for 8 minutes after... and did not see an obvious occultation, although my eye was not 100% on the target the entire time. But I did pay attention particularly around the event time, and did not see what I expected I'd see (e.g. the obvious fade such as Hilda showed the night before on a very similar circumstances event). So, a probable miss but not sure. Alas, the tape was damaged (or flawed) and it did not get recorded, and in the warm dry weather I didn't bother trying to record the display screen as I do when it's damp or very cold and there's danger of the camcorder limits being exceeded. My bad, because I got no recording. I believe the tape was a tape given to me with Karl von Ahnen's data on it some time ago and he left it with me, but I'm not entirely sure that's true. I actually can't be 100% sure where that tape came from. I have used it successfully for many events, but it was clearly having trouble for Fringilla with bad sound. For the prior night's Hilda event, the sound was also bad, and in fact when I tried to play back anything on the tape I got the dreaded black bars. Those bars may NOT have happened during the taping, they may be an artifact of poor tape / head contact on playback, it's now clear to me. So, don't feel the 'black bars' are fatal. I tried cleaning the tape heads again with alochol and also with the tape cleaner. That got the playback from being just "blue screen of death" to the black bars problem. I eventually was able to advance the tape far enough into the Hilda event to recover it completely. But the Pompeja event was not taped at all - nothing to recover, therefore.

Verdict: that was a tape from the box from Ted Blank, an old tape of unknown prior use, age, and so quite possibly at end-of-life. In the events I've tried following this, using a new tape, there's been no trouble with recordings. I think the tape heads were likely fine, just bad stretched tape.

I did not see a dip during the predicted time, but a short one could have been missed in the seeing. I will file an IOTA report with visual only and "probable miss" as my judgment.

Sky images from my place on Mtn Charlie road, about 1/4 mile from the intersection with Summit Rd.

Kirk Bender

Kirk got good data from the berm on Empire Grade. A clear miss, or if there was an event, it was so extremely short that the odds that that would be the case are vanishingly small.