The Occultation of a W=13.9 Star by the asteroid (9853) L'Epee

Jan 6, 2024 at 9:23:00pm

 

This event is moderate rank, gives 50% odds for me on the centerline at my Rodeo Gulch site. Alt=47 Az=146 in the SE in Orion on the border with Monoceros, straight below Betelguese. The event lasts up to 0.8 seconds, so don't integrate more than necessary. Clear moonless dark skies will help.

     

 

Results

I drove to the top of Rodeo Gulch. While there was ground fog in this immediate post-storm period along parts of Branciforte Rd heading into the mountains, up top on Rodeo Gulch ridge it was clear and cloudless.

Kirk and Karl both observed from home, and got recordings. Karl's however, is only an iPhone recording off the monitor; he did not attempt to use the camcorder as a recorder, given recent failures to record.

Richard Nolthenius

I set up the scope on a very clean dark moonless sky. There was some wind when I arrived, but it soon died down. The dew shield caused trouble with the breeze so I removed it. I had no corrector plate fogging despite the worry. The target star was visible but only barely and intermittantly at 16x setting, so I went to 32x for the recording. The target was consistently vislbe on each 1/2s integration, except to my eye at the occultation time, it vanished for 1 or 2 integrations. However, on reduction, I see the time stamp that the star faded but didn't disappear. It dropped to less than half brightness. It was precisely at the predicted event time. But confusing the issue is another integration 1 sec before when the star was BRIGHTER than any other integration. All other points were within the usual scatter, and PyOTE could not ID an event, and it failed the single drop test. In hindsight, I should have stayed at 16x not 32x.

My judgment is that I may have indeed I had a very short event near the edge of the path, but confidence (and Kirk's miss) is not sufficient to confirm, given the wide 32x integration periods. That's 0.6 second and for an occultation lasting only 0.8 seconds maximum. I'll note it and include light curves on my report, but formally I'll report a "miss" with qualification it might be a very short event.

IOTA report sent in for a miss Jan 12, 2024

Kirk Bender

Set up at home. Looks like an apparent miss, but a very short event could have been missed, given the long integration.

L'Epee looks like a miss, no apparent event.
16x from home.
Pyote detectability test failed at the predicted .85 sec given my noise,
said it might be detectable at minimum 1.25 sec.
This event was probably past the ragged edge of do-able, too dim and/or
short but I'll file it as a miss.

 

   

 

Karl von Ahnen

Observed from his front yard. He's given me his video, I'll have a look, but his judgement was a miss.