This is a decent event going through the central SC Mtns, north of Santa Cruz. However, Olive Springs is inside the path, where I've put down a station, after I pack up from Astro 8A. I'll have to button that class up efficiently to get up there in time. The alt=21, Az=263 in the west in northern Monoceros, just below-left of the left foot of Gemini. It's quick, only 0.4 second, but seems bright enough to be doable. Don't go longer than 4x for integration if at all possible!
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Kirk, Karl, and I all got data on this one. I had a miss from Olive Springs. Karl looks like a miss from home. Kirk a miss from Sunlit Lane. These "high rank" short events seem to not be quite as "high rank" as the orbital astrometry suggested, is my impression lately. Karl should have had a high odds of an event, and Kirk and I significantly better than 50/50 odds too.
I set up at the gate to the entrance to the Olive Springs Quarry, lower entrance (where I often use as a lunch stop on bike tours). I had some spotty cirrus but it looked like it cleared over the target a few minutes before the event. A 65% gibbous moon helped light up clouds. Calm, fairly dry feeling. 21 degrees up in the west. I recorded at 4x. Visually, the target was visible on almost all frames on the external monitor, and during the critical 10s period I focused intently and could see no occultation. I was fairly sure it was a miss, and certainly any even was much shorter than the 0.4s maximum predicted. Upon reductions, it indeed looks to be a miss. The sky was brighter than typical, and I had a fresh DV tape. Perhaps this helped to minimize the clipping in the background. The histogram did suggest still a big of clipping, but the avg of the 'no-star' looks pretty well centered on zero, so I think it had minimal influence on the analysis. I used a TME aperture on all stars.
Target star on screen capture |
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The histogram of values on the static circular sky aperture. Most of the histogram was captured, but it looks like there is still some clipping of the low end. |
The 'no-star' static circular 4px aperture light curve. Pretty well centered on zero, over all. |
I first minimized the rms in the metric interval using smoothing, and then also in time (x-axis), finding a minimum a little over 1 sec offset. Reasonable for slow moving cirrus and the close delta between ref1 and target. |
A maximum occultation would look (noise-free) like the black curve. No hint of an event. |
Karl observed from the edge of Laguna Creek Rd at "Water Truck Turn". His data shows no background clipping, the histogram continuing well below the lowest sky values. But it was done at 8x and looks to be a miss, though only 2 points would be expected to be at the minimum. Cirrus clouds drifting through are evident. I used a TME aperture for his stars, the same ref stars as I used.
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