First ever occultation of an Edgeworth Kuiper Belt Object called 20000 Varuna since the Pluto/Charon occultation will occur on 31 December, 2005. Varuna will occult star UCAC - 40675770 RA 7h 11m 6.9s, dec +25 9.51m from 6h 16m to 6h 23m UT. The star is actually 6 degrees from Castor in the constellation Gemini. The duration of the occultation is 35 seconds.
Varuna was discovered in recent times and was one of the biggest EKBOs with a diameter of 900 km. However, recent albedo observations from Chile suggests that it may be alot bigger at around 1500 km. This would make Varuna one of the 3 biggest EKBOs known. There has never been an occultation within the annals, hence the importance of this one.
This is going to be the first occultation of an EKBO and in particular one of the largest ones makes this an exciting challenge to record/time this event. The reason to record this event by accurate timing is to obtain a diameter. Albedo observations have a weaker determination as compared to a timing of an occultation. It is quite possible that if an accurate timing is successfully done the diameter could even be bigger than the other two.
It was only yesterday that final orbital calculations indicates that even with a degree of uncertainty the occultation path will go through Ireland. I did some calculations which indicate that we have a 12% of a probable certainty of this event throughout Ireland. However, if the diameter is 1500 km the certainty will be improved to 20%.
Nevertheless for the observers using integrating video or CCD
windowing, the 40 ±5 ? s expected occultation could be detected
by pushing the integration time to 3, 5 or even 10 sec., depending
on the telescope size.
If you are using a Meade 10 inch or C11 telescope and a Watec 120N or similar video camera (integrating camera) could detect V= 15.7 (probably R~ 15.1) with 3 sec. integrations with average 3 secs arc seeing in Ireland used the f/10 focus, i.e. no focal reducer. Using 10 sec integration will get down to 16.5 mag.
If anybody is interested I have some field charts for the area.
Good luck and clear skies
Eamonn A
