My early planned site, on Glen Canyon Rd. But elevation is only 480 ft, which is likely to be fogged out.
This is the brightest asteroid event in Central California in many years, and crosses through Santa Cruz county. The altitude is only 9 degrees up in the Southeast, azimuth 114, rising. You'll need a special flat horizon to get this one. It's a single line spectroscopic binary, indicating it has a much fainter companion close in. This will scramble the path a bit. It also has a RUWE of 1.40 which is a bit ragged. The duration at maximum is 0.55 seconds. For reductions, I'd suggest trying a wide circle in PyMovie, since sky noise will be nil compared to such a bright star; the danger instead will be losing starlight to wider scattered pixels.
The special value may be in determining the brightness of the companion star. The projected sky diameter of the star is 1/3 the diameter of the asteroid, so the event will be gradual at a certain level. I'd suggest cutting the exposure as small as needed to make sure you avoid saturated pixels, in order to get the proper brightness of the companion star, and analyze in field mode. No more than 1x integration, and possibly even less.
Finding a suitable site with a good enough horizon has been hard so far. I have found a spot on Glen Canyon Rd which has a 6 degree horizon by looking through a narrow slot cut by Glen Canyon Rd, towards the ridge behind it. Horizon at Az=113 is 6.0 degrees. Good enough. You might be able to find a spot on Empire Grade just below the fire station with a low SE horizon. I know I pulled off on the shoulder there once and got an event in the SE. The path is a bit uncertain so spreading a bit to not all be on the centerline makes sense.
Other more fog-free sites? Quien Sabe Rd east of Hollister looks promising, although it's a long dirt winding road through the hills. Perhaps better is Little Panoche Rd, past Mercey Hot Springs. Or, if the road into the Panoche Hills Rec area is open, up there would have cleaner skies and viewing east. Locally, the Eco-Preserve at 1600 ft elevation looks best, if you position perfectly to get the low SE horizon from there.
My early planned site, on Glen Canyon Rd. But elevation is only 480 ft, which is likely to be fogged out. |
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It's now 8 hrs before the event. Cloud pictures are showing it's not wise to stay in Santa Cruz County, although it looks better for Karl than for Bonny Doon. Karl is above the path, but with the rank and the RUWE of 1.75, he could still get an event and anyway provide a valuable constraining miss if not. Kirk and I are now planning on sites SE of Hollister or Little Panoche Reservoir.
Total cloud cover from Bonny Doon site and target azimuth direction to target. Also from Karl's claimed site, which looks a little better. Fog mostly hugs the coast and inland some, otherwise it is high clouds that provide the opacity inland. |
Total cloud cover (all high clouds) from Little Panoche Rd near the reservoir, and azimuth towards target |
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