Grazing occultation observed from public observatory Bussloo

Despite poor weather forecasts, the sky cleared for a couple of hours right on time for the grazing occultation of star HD69809 (Cancer, m=7.9). The occultation was visible from Public Observatory Bussloo (Netherlands). Six observers in total gathered at the observatory in preparation of the occultation. Hendrik Beijeman and Tom Borger found a place 500m to the south of the predicted limit line and observed two occulations. Jan Maarten WInkel was observing from a site 1400m south of the line and observed a short occultation followed by the complete disappearance of the star. Alex Scholten was the most southern placed observer 1700m south of the line and he saw a complete disappearance.  Mark-Jaap and myself observed from the observatory, 250m south of the limit line. Mark-Jaap shot the occultation with a Celestron C8 and Canon EOS 70D in video mode. I used the observatories’ Celestron EdgeHD1400 with a Watec902 camera, a EZCap frame grabber, AME Video Time-Inserter TIM-10 and VirtualDub.

At the observatory two occultations occurred:
21.36.47-21.36.57 and 21.37.44-21.37.45 (timings in UT).

See below movie clip covering the period 21.36.30 – 21.38.00 UT.


Analyses using Limovie and Excel.
Left: the first occultation. Right: the second occulation. (note the gradual light drop-off!)












Positions of observers.
Black line: limit line.
Red line, 250m south of limit line:
– VSB,Mark-Jaap: 52°11’50.2″N / 06°07’08.4″E
– VSB,Jaap: 52°11’50.5″N / 06°07’09.3″E
Yellow line, 500m south of limit line:
– Tom: 52°11’59.4″N / 06°06’28.3″E
– Hendrik: 52°11’58.7″N / 06°06’27.7″E
Green line, 1400m south of limit line:
– Jan Maarten: 52°11’49.4″N / 06°05’23.6″E
Blue line, 1700m south of limit line:
– Alex: 52°10’45.1″N / 06°07’22.7″E