To see it, requires staying pretty close to Santa Cruz. Karl's track could be a useful 'miss' however.
ECW cloud forecast; looks good enough.
This is a decently do-able event, lasting 2.7 seconds, in Gemini halfway to Procyon, near the open cluster NGC 2355, on the top edge of the eyepiece field when locating the target. The open cluster is only 9.7 magnitude though, so it may not be very obvious. The target is at altitude 62, Az=142 in the SE, nicely placed for me at home from my carport. The weather forecast map shows mostly clear skies by then, although it's pretty cloudy in the afternoon. The drop is 1.5 magnitudes, so the asteroid itself should be dimly visible with sufficient integration. Since the event lasts up to 2.7 seconds, I'd not suggest 2x setting, but at least 4x to get better sky subtraction. Maybe 4x or 8x for Karl, especially if he'll end up with a iPhone recording.
My plan is to observe Klumpkea from home at my driveway, then hurriedly repack into my RAV4 and drive up to the Upper Meadow UCSC and set up again for the 2nd event at 10pm. I should have enough time, if all goes smoothly.
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To see it, requires staying pretty close to Santa Cruz. Karl's track could be a useful 'miss' however. |
ECW cloud forecast; looks good enough. |
I set up 3 car spots north of West Cliff, near Natural Bridges State Park. Skies were clear, cold, and damp, and I had an unobstructed view 62 degrees up to the target. Set up went well, ID'd the field of view on first try. It seemed I should use 4x setting, but as time got close, I couldn't see the target well. Perhaps re-focusing with more care would have convinced me I could use 4x. Instead I went back to 8x, where the target was quite easily seen on every frame. My impression while watching was that the event was only 1s long, but in fact, I see on PyOTE reductions that it was 1.7s long, which is more consistent with Kirk Bender's 1.5s duration. 8x setting. I used a 5px circular static aperture in PyMovie, and in PyOTE I set the entire pre-occultation period as the metric interval, and minimized the figure of merit, giving the results below.
magDrop report: percentDrop: 73.0 magDrop: 1.422 +/- 0.311 (0.95 ci)
DNR: 3.90
D time: [05:02:56.4989]
D: 0.6800 containment intervals: {+/- 0.0394} seconds
D: 0.9500 containment intervals: {+/- 0.1003} seconds
D: 0.9973 containment intervals: {+/- 0.1992} seconds
R time: [05:02:58.2589]
R: 0.6800 containment intervals: {+/- 0.0394} seconds
R: 0.9500 containment intervals: {+/- 0.1003} seconds
R: 0.9973 containment intervals: {+/- 0.1992} seconds
Duration (R - D): 1.7600 seconds
Duration: 0.6800 containment intervals: {+/- 0.0570} seconds
Duration: 0.9500 containment intervals: {+/- 0.1297} seconds
Duration: 0.9973 containment intervals: {+/- 0.2393} seconds
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I got a 1.7291 sec event. I used 16x. I probably could have used 8x or maybe even 4x, but I didn't have time to experiment after the failed align from the tilted tripod.
It wasn't saturated at 16x though.
magDrop report: percentDrop: 68.8 magDrop: 1.265 +/- 0.390 (0.95 ci)
DNR: 4.72
D time: [05:02:56.4944]
D: 0.6800 containment intervals: {+/- 0.0602} seconds
D: 0.9500 containment intervals: {+/- 0.1471} seconds
D: 0.9973 containment intervals: {+/- 0.2830} seconds
R time: [05:02:58.2235]
R: 0.6800 containment intervals: {+/- 0.0602} seconds
R: 0.9500 containment intervals: {+/- 0.1471} seconds
R: 0.9973 containment intervals: {+/- 0.2830} seconds
Duration (R - D): 1.7291 seconds
Duration: 0.6800 containment intervals: {+/- 0.0907} seconds
Duration: 0.9500 containment intervals: {+/- 0.2020} seconds
Duration: 0.9973 containment intervals: {+/- 0.3585} seconds
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Karl von Ahnen
Unfortunately, Karl took my advice to tilt the tripod to avoid the high altitude troubles on the 1996ER1 event an hour later. We've confirmed that the 8SE does not GoTo properly if you tilt the tripod head more than a tiny amount. In the future, the advice is to always leave the tripod head level. If the target is above 75 degrees altitude, then we'll have to use the 2" diagonal left in, then 1.25" adapter, then insert Watec with 0.5x nosepiece and just accept the fuzzier optical focus. So, no data.
In hindsight, I realize that for Karl and Kirk, both staying home for these events, that 1 hour is enough time that a fresh 2-star align should not be a problem. And they should have set the tripod flat for the Klumpkea event and only tilt it afterwards with a new 2-star align. And now, we're not going to do any tilting at all in the future.