Sep 2015

Aldebaran Occultation Success!
by John Hlynialuk

The early morning Sep 5 Aldebaran occultation was successfully observed by two determined BAS members observing from the Kemble Lookout on Grey Rd 1. Anton V. and John H. set up with refractors and binoculars at 11 pm in plenty of time to see the event. At first, the clouds hid the NE horizon (Sag and Sco in the MW were visible in the south) but the prevailing winds were carrying the thicker clouds away from the critical point where the moon would rise by the predicted moonrise time (11:51 pm Sep 4). Anton spotted the top of the Moon first and John very quickly zeroed in with the refractor and snapped the image below. To our astonishment, Aldebaran was visible as a red dot near the top limb of the Moon which could not have been more than half a degree above the physical horizon. Canon 60Da, 540 mm foc.len. f/5.4, ISO 2000, 1.0 s exposure.


John kept snapping away and was able to bracket the disappearance at the bright edge as sometime in the 8 seconds between 12:06:54 am and 12:07:02 am. It was not visible to the eye (clouds got in the way) but under close examination of the individual camera frames there was a faint image present on several critical frames around that time.

During the entire event, some clouds were interfering with the clarity of the sky, but the reappearance at the bright limb occurred in relatively clear sky. It was seen by both (very pleasantly surprised) viewers, Anton through a 3-inch 500 mm fl. Skywatcher refractor (at 12.5X) and John through the viewfinder of the camera mounted on the TV NP101 as the camera clicked away. Reappearance time was 12:40:44 am

By that point, the Moon and Aldebaran were in relatively clear sky as seen in this image below taken more than 8 minutes later at 12:48:29 am. Canon 60Da, 540 mm foc.len. f/5.4, ISO 2000, 0.04 s exposure.


Both of us were able to see Aldebaran with the naked eye a few minutes after the reappearance and watched it gradually move farther and farther away from the dark limb as we made our way home completely satisfied at having observing a very rare event. Chalk up one more item on the life list of astronomy sights!

John H.
PS. Just a heads up, there are 4 more Aldebaran occultations, but only 2 are visible locally. One of those is a daytime event (Oct 2), the other is in dark sky but the full moon is involved (Nov 26). Stay tuned for details.