This is a very difficult event. The occultation lasts long enough that a long integration could probably see it. However, the real limiter is going to be the full moon, which is only 9 degrees away. The skies look very clean and clear, though, as I write this 5 hours before the event. The altitude is 68 degrees in the west. The event could last up to 9s. The other difficulty is the path, which looks to be very high rank but the northern limit just skims Natural Bridges State Park, and to do significantly higher odds of getting the event (46% at Natural Bridges), you'd have to drive all the way to Beach Street near the Pajaro River. At 2:09 am, and with a trail hike in Carmel that I'll be driving do at 9am later that morning, that's killing a lot of sleep for a very iffy possibility. I'm hoping Kirk gives it a try from home, or perhaps drives to Natural Bridges where his odds improve to 46% instead of 30% from his home. Or, let me know his plan in any case. I'm pretty tired - from a 10 mile very hilly trail run through Nicene Marks State Park today Saturday Dec 18.
Here's the charts...
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I was too exhausted to try this, and the odds looks too iffy to sacrifice a badly needed night of sleep ahead of my visit with Steve K from Utah for my one visit of this year - a 7 mile hike in Garland Ranch in Carmel Valley. Kirk's schedule was more forgiving, and he made the midnight drive to Moss Landing in order to get this very tough event - and succeede! Albeit with not our usual precise timing accuracies, due to the noise.
To see the disappearance of a 14.3 star only 9 degrees from the perfectly full moon, at only 4x integration, is the most difficult challenge of our equipment yet. I'm glad he got this, and I'll use this in my forward planning for other events. I'm sure that if I'd tried it from home, I'd have not been able to distinguish a short occultation near the northern limit, however. It's only because Kirk took the effort to drive close to the centerline and hope for a long occultation that the S/N was good enough to say it's a positive.
Site, near the 76 station in Moss Landing |
Damn tough, trying to do photometry on a super faint star in the glare of a full moon only the "bowl of the big Dipper" diameter away. |
Cirrus clouds and jet contrails also made it more "sporting". They hid the target for a time, but cleared away from the target before the event. Kirk also commented that the scope motor failed on trying to align on Polaris the first attempt. Possible cause imbalance? Maybe his battery was lower voltage, in the cold? |
The PyMovie photometry file. The blue curve is the target. The dip is just left of the middle. |
PyMovie light curve, all, of just the target star. The occultation dip is long enough that it stands out against competing much shorter noise dips. |
Zoomed in on the PyOTE integrated light curve, with timings and accuracies plotted. |
False positive graph - the red line shows the false-positive probability is zero. |
PyMovie screen capture |
