The (96) Aegle Occultation

Dec 29, 2015

This event had a high rank, with the southern limit predicted to pass just north of Cabrillo. I contacted Karl and, being the holidays, decided to do a mid-week "movie night" at his place off Highland Way. First, I committed to a final swim workout for the year with Rick Ferrell at the gym, then drove up Old SJ Rd to Summit and Highland to Karl's, getting there and parking in his driveway with just 40 minutes to spare. I set up as quickly as I could, having to use Hamal and Aldebaren for alignment stars; difficult as they're only 1 constellation apart. When I did a "go to" the target, the star pattern was hard to identify as the pointing was not great. But it all eventually came together, and with a full 2 minutes to spare, I was on target and ready to tape. I set the camera at 8x (4 frames) for the 11.8 magnitude target.

The Q70 eyepiece finder chart. Conveniently, NGC 229 was right next to the target star, which was the easy way to GoTo the target on the LX200 scope

Karl's place, in Google Earth, with coordinates shown at lower right. Elevation 1607 ft.

No PSF tracking. Target tracking "OFF", tracking star (yellow) "drift" and "Linked", comparison star (pink) "drift" All objects had 5/7/25 photometry circles. Target reappeared inside the inner circle after being gone 9 seconds

The LCD screen, with the target at 11.8 magnitude and dim but steady.

LiMovie light curves. Target is blue, at bottom. The comparison and tracking stars both show a slight trending drop in brightness, but less so (?) for the target star. Not sure why.

Same, zoomed in. Using the integration points on the rising R portion, I verified 4 points per integration, with offset=0

The noise histogram from the Occular solution

The Occular solution to the light curve, with parameters. There is no color information for the star, so I guesstimated a solar-type photographic magnitude so as to enable Occular to fill in the magnitude information.

100 Monte Carlo solutions; this is the D and R solution distribution

The final report. Occular noted that observed magnitude at minimum did not agree with the expectation, but that was no doubt because of the unavailable color information. Does not affect the D, R solution.

Our team: Shahram, me, Tom, Karl... mostly they chatted while I hurried to get set up in time.

Business end of the 10" LX200, with Watec 910hx videocamera, about 10 minutes after the event.

The LiMovie output light curve .csv file, and the IOTA report. And, here's the final silhouette profile of the asteroid, from all observers.

Afterwards, I packed up the gear into my RAV4, and we headed inside for some snacks and vote on the movie to watch... we decided on "Mad Max - Fury Road" - a pretty over-the-top actioner.