Occultation of (165) Xanthippe on Oct 29

Forums Asteroids Occultation of (165) Xanthippe on Oct 29

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    David Arditti

    Good weather, but unfortunately I couldn’t find the 12th magnitude star in time.

    I started setting up about an hour in advance, and because it was cold, I tried to do the operation from my warm room, but I couldn’t get the connection to the camera to be reliable from there. So I then transferred the computer to the observatory, where the connection worked, but I couldn’t see the planetarium display. By then I had lost so much time I didn’t want to investigate the under-floorboard wires to transfer the planetarium display as well, so I tried to find the star just from the RA and Dec. the mount believed it was pointing at. But this was not reliable enough, and I imaged a star at the predicted time, but it was the wrong one, and didn’t correspond to the downloaded chart. Then I did take the floorboards up to find the wire to place the planetarium display next to the imaging computer in the observatory, and by carefully stepping from known brighter stars to fainter ones, found the required field, about an hour too late.

    I could not have achieved the required accuracy, though, of 0.2s, because the star was barely recorded by the Point Grey Grasshopper 3 camera at prime focus of the C-14 with a 0.2s exposure. It required 0.5s to show it clearly, so that would have been the limit of accuracy with this equipment. This is useful to determine, for future reference.

    I hope others had better luck.

    Steve Knight

    Bad luck.  Managed to get it.  Was going to use a planetary camera but events intervened.  Plan B was a DSLR so lousy timing accuracy.  All I can say is star was visible at 19:19:04, missing at 19:19:07 and back again at 19:19:10.

    Peter Carson

    I’d been away for a short holiday and was due back Monday evening. My return journey plans were running late but I returned home with time to spare before the event. The sky was lovely and clear and I started scrabbling about making preparations for the observing run only to realise there was too much to set up in the time available.
    I then decided to have dinner put my feet up and plan how to make the observatory more pre-prepared for the next similar event.
    Oh well.

    Grant Privett

    It was a little hazy near Salisbury in Wiltshire but Astrometry.net is down so I am not sure which star is which. Will have a look later today. And with a 4×4 binned Starlight 694 doing the imaging I’ve only one image every 3 seconds. It was a chilly night.

    Late addendum: From my location near Salisbury duration at least 191905.2-191908.0

    Exposure 191855.0 – 191855.2  36593counts 178snr

    Exposure 191858.0 – 191858.2  36114counts 176snr

    Exposure 191902.0 – 191902.2  34820counts 170snr

    Exposure 191905.0 – 191905.2  14824counts 78snr

    Exposure 191908.0 – 191908.2  13304counts 69snr

    Exposure 191911.0 – 191911.2   37475counts 181snr

    Exposure 191914.0 – 191914.2   38728counts 187snr

    David Arditti

    Yep, this is the kind of thing that really needs a dummy run on an earlier night to get a feel for the difficulty of the problem. Glad so see some observers got something, if nowhere near 0.2s cadence.

    Tim Haymes

    I didnt have much trouble finding the star with WAT-910HX and 30cm.  I did a goto to a nearby bright star, focused, synced and then offset to Xanthippe and there it was !  Just where skymap plotted it. This was about 45 min before hand as i didnt want to risk having a problem and no time to sort it. I did a dummy recording and was OK.  The asteroid was detected  at mag 13.5.  (star at 11.9). The asteroid moved closer and then “star gone”. The video recorded a duration of 5.70 seconds at 25fps in good conditions.  Some observed chords are now on EURASTER.NET 

    Sorry some of you had some bad luck with technical issues. It was a clear night here, but seeing stability was abysmal. The ARPS section has received over 12 observations.

    Richard Miles

    The previous evening to the Xanthippe event was nice and clear so I did a practice run doing things like finding the star and taking a picture of the field on the screen using my iPhone so I knew exactly which star was which. I also found out that the OccuRec software for recording the video was playing up and so I sort of found a way around that issue well ahead of time. Am still on a learning curve as to how to set up to avoid disappointment but hopefully we’ll have many more similar opportunities to go after in the future. But a practice run beforehand is a great idea.

    (P.S. For the Titan/28 Sgr occultation in 1989, we were able to do a dry-run at the same clock time as the real event the next day – it made all the difference then too!)

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