Is there still scientific value in timing and reporting total lunar occultations? Why would I time total lunar occultations (grazing occultations are out of the question)?

When I reported observations to ILOC many years ago I never got any feedback. Is the situation better today? There are apparently new arrangements, but are they actually working, for example, how is feedback provided to observers?


I suspect they are no longer of much scientific value. They were originally used to refine the shape of the lunar limb, but we now have abundant data from various orbiters around the Moon. Attention has shifted to grazing occultations and occultations by asteroids, especially the latter. Apparently the International Lunar Occultation Centre (ILOC) has ceased operations and has been supplanted by the International Occultation Timing Association (IOTA).

I used to time lunar occultations back in the '50s and '60s, but nowadays I time asteroid occultations.

Source: http://lunar-occultations.com/iota/lunarreport.htm http://www.lunar-occultations.com/iota/iotandx.htm

  • $\begingroup$ Interesting. What is the hit rate on asteroid occultations? Has the Hipparcos data increased it to something more acceptable than 10% in the 1980s? $\endgroup$ – Peter Mortensen Jun 1 '11 at 23:46
  • 1
    $\begingroup$ The hit rate is now very high for exactly the reason you cite, vastly improved astrometry. Misses are mainly because of the shape of the asteroid. Ideally several observers are spread across the predicted shadow path, and exact timings produce a good indication of the shape of the asteroid. This is really exciting work! $\endgroup$ – Geoff Gaherty Jun 3 '11 at 15:43

There is an upcoming lunar occultation of the Crab nebula, sometime in October I believe. This is still sufficiently interesting scientifically that they have extended the lifetime of the RXTE mission in order to observe this event. One reason is that high-energy X-rays are still not very easy to image, so occultations give relatively high precision astrometry information. I believe this was actually one of the ways they proved that Quasars must be extremely compact, and thus most likely black holes.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.