Observation by Tim Haymes: Asteroid occultation of a v13.6 star

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Tim Haymes


Tim Haymes


2021 Aug 23 - 20:52


2021 Aug 26 - 15:05


1434 Margot

  • C11 XLT at F5.6
  • QHY174-gps
  • SharpCap v 3.2.6482
  • TANGRA for light curve measurement

200ms, 3 minute SER recording


Oxfordshire, UK

Target name

(1434) Margot and UCAC4 378-145495


Asteroid occultation of a v13.6 star

About this image

Perhaps not the most exciting report, but typical of a faint star occultation in good conditions.  Here, the star (blue light curve) disappears for 3.7 seconds occulted by the fainter asteroid (v15).  The star field in Sag. was just clear of the dome wall.

Of interest is that the light curve does not go down to zero(background). The reason for this is a fainter star about 10" arc from the occulted star is contributing to the measurement aperture.  It was a very good prediction for two reasons: The observed mid-time was within 1 seconds of the predicted time, and the chord length agrees with my location. 

Where did i get the prediction? Well i now use OccultWatcher V5. This takes the predictions from a Cloud server (access is build into the application).  The server calculates several predictions which can viewed in Google Maps.  OccultWatcher is configured by me to show predictions crossing Oxfordshire where i observe them. I happened to be near the middle of this shadow, and i still count myself lucky to have recorded it, as so much can go wrong  - wrong star, uncertain prediction, bad weather, technical issues etc..   This is my 48th confirmed positive occultation since 2010.



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Tim Haymes
Tim Haymes, 2021 Aug 28 - 10:16 UTC

I should add, that the observed chord length and mid time is not unique. The same would be observed the other side of the mid line.  A second observation could have removed this ambiguity.

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