The Occultation of a W=11.6 Star by 2002 AX123

Tue July 9, 2024 at 10:07:50pm

 

This is a good rank event passing through Santa Cruz, missing Karl, but getting far enough up Empire Grade to make the bike crossing a decent spot. So is "the Berm", but going beyond that is getting pretty close to the northern limit and odds drop and so does the duration of the event. But can get from home if fog stays away. Duration = 0.4s but the star is bright and do-able at 1x or 2x so 0.4s should not be a problem.

Alt=22, Az=147 in the SE. Duration 0.4s at max. Full drop. Location: the target star is just above the tip of the top of the Teapot lid of Sagittarius. It should be visible from my place, but I'll drive up Empire Grade to the bike crossing if fog threatens but stays low.

     

 

Results:

Richard Nolthenius

This path was difficult; it mostly hugged low elevation, and the fog came in and ruined those locations. The best spot was "the Berm", which I gave to Kirk. I hoped it would stay clear at the bike crossing upper UCSC, but when I arrived, I could tell the clear skies would not last the remaining 45 minutes till the event. The fog tops were essentially at 1200 ft elevation, same as the site. So I got back in my car and drove north, hoping to find a place I had a view of the low target but not on top of Kirk at "the Berm". The first place I could find, was a driveway at 6240 Empire Grade, which had a narrow view of Sagittarius looking straight down Empire Grade. Not at all ideal, and north of the nominal northern limit, but still useful if I could get data. I integrated at 2x. I got set up fast and efficient, but uphill traffic was indeed blasting headlight right down my telescope dew shield and blinding the Watec. But cars were not common and the blind period was only a few seconds, so I counted on not having horrible luck. Alas, as the event time approached, I could hear an up traffic car. I figured it would pass me by the time the event happened, 30s in the future. but it was slow, and it in fact arrived seconds before the event, and worse, it had 2 more cars waiting behind it, and they all added their lights into the telescope tube. I don't know if I'll be able to tell if I got an occultation; it may require single-frame by frame playback in PyMovie. I integrated at 2x, as did Kirk. A full 0.4s occultation would then be 24 x 0.4 = 10 integrations. The odds of having only a single integration occultation is highly unlikely, and there are other single frame drops to zero throughout the recording. It looks highly likely to be a miss, as it was for Kirk not that far away. This means the path shifted significantly, again.

long: 122 06 46.81
Lat 37 02 51.24
Elev: 1810 ft.

       

 

Single frame by frame zoomed in playback in PyMovie shows a miss, except for the single frame which dropped to ~zero. However, the light curve showed over a half dozen other single point drops to ~zero, best interpretation is "miss".

Kirk Bender

Kirk also had a miss, with better data unspoiled by car headlights.