Occultation of TYC 2904 0849 by 385 Ilmatar 

In response to this occultation alert from Richard Miles, I attempted to video this event, using an Astrovid 2000 video camera on my 50cm f/4 Newtonian.

385 ILMATAR early on Sunday evening, January 10/11

This medium-sized asteroid, some 94 km across, is predicted to occult the star, TYC 2904 0849 (V=9.64) soon after dusk on Sunday evening. Details are as follows:

Location of star:RA(2000): 05h 18m 52sDec(2000) +42deg 24'04"

Observational coverage should span 18:17-18:29 UT, with the expectedmid-time (from the UK) = 18:22:42 UT

Event Rating: Favourable

The maximum duration of the event is expected to be about 9 seconds. The star may dip in brightness by about 2.1 magnitudes (i.e. by a factor of about 7).Note that seen from the UK, the event takes place at a high altitude above the horizon in the range, 48-54 deg, and an azimuth of about 84 deg. The Moon will not have risen and so will not interfere with observation.

Observers equipped with a telescope, CCD, or photoelectric photometer may wish to monitor this very close appulse / occultation.


January 9th : Preparations the night before....identifying the field of view

With the prospects of clear skies this favourable event was worth preparing for, and so the evening before I located the field and recorded this image with my SX CCD and 50 cm f/4 Newtonian: The star to be occulted is the brightest one  in the centre of this image ( 40 sec exposure). At this stage I hadn't yet identified the asteroid.



January 10th : The night of the Occultation

The skies were beautifully clear throughout, and conditions were near perfect. I started imaging the field at 1800 hrs,  the asteroid Ilmatar was easily seen (10 sec exposures with SX CCD and 50 cm f/4)  a few tens of arc seconds  north following the star. Having satisfied myself that I was on the correct star, I swopped over the CCD for the Astrovid 2000 and began videotaping.With the gain turned up to maximum, the camera was successfully recording the star TYC 2904 0849  and two other fainter ones in a field of view of about 12 arc minutes. It was however  not sensitve enough to record Ilmatar.  I don't have a time and date generator on this unit so put a time signal in the sequence  by flashing my torch into the scope at 1815h U.T. precisely.  I  ran the camera until 1830h U.T. but was unable to confirm a positive occultation. There were a few times which I  noted at  18h 17m 47s when the star appeared to momentarily fade, and also at 18h 18m 20s, but I think these were caused by moments of poor seeing, and only lasted a second or so,  there were certainly  no pronounced fades. The eight images I obtained with the CCD camera from 1802hr until 1848hr I have assembled as an animated gif and displayed below: ( South is at the top).

Worth Hill Observatory Index Page