This event could be rather difficult, but happens just an hour or so after a better event, so it's a 2-for-1 once we're set up. The drop in magnitude is list as 0.1, but in fact in the R band which is closer to what we have for the Watec cameras, the drop is listed on OWc as 0.5 in R. It may then be about 0.3 for our Watec cameras bandpass. It lasts up to 17s and so we can do good long integration to get the required S/N. Just avoid saturation of any pixels. Altitude is low, only 18 degrees, due south at 182 Azimuth. The star has a poor RUWE and that means a significant shift is quite possible. That is probably good for us, since we're nominally outside the path and closer to the 1-sigma limit. With the poor RUWE, our odds of a "hit" are probably more like 50/50, and the duration may be closer to the maximum 17 seconds than would otherwise be expected.
The path is very wide since it just grazes the Earth. The center line is actually at Mt Lassen! The nominal path accuracy is about 10% of the path width but because of the low altitude, low declination, then moving yourself on the Earth won't change your odds of a hit very much. Especially true when you look at the high RUWE=3.95; far above the safe limit of 1.19 to accept good star position accuracy. The southern limit through San Francisco and Mt Hamilton. We can drive into the BD area to get above fog, and improve odds a little. Karl's better positioned, but all of "Team Santa Cruz" have odds of a hit of about 50%, given the high RUWE.
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Kirk and I had clear skies above a low thin fog layer which covered the main campus of UCSC but not the upper Meadow, and not higher up where Kirk observed. We both got solid positives. Karl had trouble with time management and did not get on target in time.
I used settings of sharpness=4, integration=8x, gain=39, gamma=1. I had no saturated pixels on the stars I used, including the target. I used 4.5px static circular apertures on each star in PyMovie.
PyMovie screen capture, with target star in the aperture below |
PyMovie target star light curve. Event is just before the midpoint |
I put apertures on 3 reference stars, including the target, none on "no-star" since the dip was going to be so shallow. PyMovie composite lightcurves |
I used reference star 2, the quietest light curve of the reference stars, as the reference star in PyOTE |
The false positive test, passed with high statistical significance |
The PyOTE reduction, with reference star at top. |
Pyote light curve with solution |
And, zoomed in, with timings below |
Kirk's data will be posted soon. He'll send his IOTA report separately
