Asteroid occultation on June 14

[PTS]

Hi,
There will be 5 asteroid occultaions visible in HK.
Here is the second one. Attached are finder charts.

-------------------------------
IOTA/IOTA-ES occultation update for
(1236) Thais / TYC 7900-01048-1 event on 2010 Jun 13, 19:45 UT
Visible from China, SE Asia, Africa


Summary
-------
On 2010 Jun 13 UT, the 22 km diameter asteroid (1236) Thais will occult a 10.9
mag star in the constellation Corona Australis for observers along a path across
China, SE Asia, Africa.

In the case of an occultation, the combined light of the asteroid and the star
will drop by 3.9 mag to 14.8 mag (the magnitude of the asteroid) for at most 2.2
seconds.

This update is based on UNSO/Flagstaff astrometry for the asteroid kindly
provided by Alice Monet, historical astrometry from the MPC files (via AstDys),
and the following catalogs for the star position: UCAC.

The event at a glimpse
----------------------
* Rank: 27
* date and approx. time of event: 2010 Jun 13, 19:35 - 2010 Jun 13, 19:55 UT
* midpoint of event [JD]: 2455361.32339167
* magnitude of target star: 10.9
* magnitude drop [mag]: 3.9
* estimated maximum duration [s]: 2.2
* Moon: 2 % sunlit, 164?distance
* Sun: 161?distance
* rough path description: China, SE Asia, Africa

The occultation path
--------------------
* approximate projected width [km]: 23
* 1 sigma uncertainty interval [path widths]: +/- 2.51
* 1 sigma uncertainty interval [seconds]: +/- 5.5
* 1 sigma uncertainty interval approx RA,DE ["]: (+/- .084 +/- .044)
* 1 sigma uncertainty ellipse (major, minor, PA): ( .085", .042", 99?)
* approx speed of asteroid's shadow [km/s]: 9.9577
* website for maps:
http://www.asteroidoccultation.com

[PTS]

The sky seems not satisfactory.

PTS

[MANDII]

Dear PTS ,

Very Good .

Do you know what kind of scope is neccessarily needed to observe the Asteroid(小行星??) ?
how much aperture , and how much total maginification in minimun , is needed if I just want to see it on an eyepieces . I think the tracking is not necessarily needed in visual observation only .


MANDII

[PTS]

Dear PTS ,

Very Good .

Do you know what kind of scope is neccessarily needed to observe the Asteroid(小行星??) ?
how much aperture , and how much total maginification in minimun , is needed if I just want to see it on an eyepieces . I think the tracking is not necessarily needed in visual observation only .


MANDII

The asteroid is fainter then 14th magnitude, and low in the southern sky. It would be difficult to visually observe it in this heavily populated star field, even with large telescopes.

To the contrary of your belief, accurate tracking is essential or you will lose the asteroid fast. I usually observe at Hokoon because of, apart from the large aperture, the very accurate tracking system of the mounting. During observation of these events, I usually use a single star to initialise the telescope, and then command the TCS to slew the telescope to the coordinates of the star. Without such marvelous drive, it would be very tedious, if not difficult, to pin point the target star. This is also why I post these finder charts from the Digital Sky Survey database (stars are shown to some 20-21 magnitude) in addition to the map generated by TheSky 6.

If the sky is clear by 10 pm tonight, I'll be observing at Hokoon with the 0.5 m telescope, with a StellaCam3. Even with this setup, a very clear sky is needed if the asteroid can be recorded.
However, for asteroid occultation timing, there is no need to see the asteroid itself. All we are aiming is the "occultation" during which the star (in this event, a 10th magnitude star which will be easily recorded in my setup) will be occulted (like eclipse).

The video signal from the StellaCam3, as well as the signal from my Garmin GPS unit will be fed into my Kiwi OSD, which will combine these 2 signal and feed into my Firewire capture box, which captures the video stream into my computer. This way, every single frame of the video stream will be stamped with the time signal from the GPS.

If the observation is successful, the video stream will be analysed (usually the indivual frames are extracted and examined), and the starting and ending times of the occultation will be estimated. A report will be made and sent to a colleague of the Japan Astronomical Observatory for further analysis.

PTS

[MANDII]

Dear PTS ,

Understand .
And thank you .

MANDII