The Occultation of a 13.0 Star for 1.2s by Asteroid 1999JF95

Sat eve Feb 21 at 8:40:34pm

OWc page

 

This event is long enough to get at the 4x or 8x needed to get decent brightness. However it is at 75 deg altitude, and higher than that during the prior time when acquiring the target. This one will need the diagonal to avoid running into the mount base. I've set a site along San Andreas Rd near the centerline. Rank is good, and odds of a "hit" are high.

The charts below are all left-right reversed and assume the diagonal is in the optical train. The big box is the 8SE with f/3.3 reducer. The little box is smaller than the f/6.3 field and was an estimate of what the 12" scope with f/6.3 should approximately be. For the 8SE telescope we all have for mobile work, the f/6.3 will be about half the diameter of the sqauare chip.

Note, if you have trouble ID'ing the star field, don't waste too much time trying to make it fit. Try going to "IC 405" and identify the characteristic star field there. But if that even fails, get on the target with the Watec and crank up the integration so that you have lots of stars to work with, and use the middle chart below to try to find it, and don't be too picky about the exact orientation, since the orientation will be rotating during the find/observe period.

Alt=76, Az=262 in Auriga, inside the Pentagon

   

 

Results:

Richard Nolthenius

After off-loading Kirk, I tried to find a site protected from the wind, as I did not trust my car to do a good enough job on its own. I found an strawberry field's plastic fence about 5'6" high, good enough to work. But full of holes letting the wind through, I drove back some and found fencing w/o wind holes, nestled my car up against the fence as well as possible, set up the scope on a strong muddy slope, had to work some to get the tripod level what with settling in the mud and steep slope. Did 2-star align OK, with Hamal and Regulus very far apart. did a GoTo IC 405 whose star pattern I thought I'd easily recognize... but did not, after 5 minutes of searching. I then did a GoTo the target to see if that was better for star patterns. I finally did recognize the field's line of faint straight stars, rather twisted away from expectations on my chart. I centered the scope on the area of the target, put in the 0.5x reducer on the standard nosepiece, got it focused by about 7 or 8 CCW twists. And could not recognize any of the star patterns at 8x. I spend the rest of the time I had doing a spiral search for something recognizable, but never did. Re-GoTo'd the target coordinates, and recorded, but felt I was probably off-by a fair amount. Another frustrating experience for a high angular altitude event.  I recorded the position VTI setting to get long/lat.

         

 

 

Kirk Bender

Observed from the "San Andreas Community" with good wind protection. Had some characters who made him uncomfortable. But did get the target on-chip and recorded