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PostPosted: Mon Nov 06, 2017 4:20 am 

Joined: Fri Dec 03, 2004 12:51 pm
Posts: 2513
Location: Stoke-on-Trent
I've managed a few sessions, over the past few hours, watching the Moon passing in front of the Hyades star cluster, starting on the evening of 5th November and going into the very early hours of 6th November. It was good to have a continued period of relatively clear skies for such an event.

The first session was from 10:45pm through to 11:55pm on the 5th November, using a William Optics 66mm refractor. At approximately 11:05pm, I saw the Moon's closest approach to the magnitude +3.81 and +3.37 stars Theta1 and Theta2 Tauri. It's been a long time since I observed one of these events, and I wasn't sure how much I'd be able to see, given the equipment I was using, but I was pleasantly surprised at how easy it was to pick out these two stars against the glare of the Moon. I should have checked the timings a little more closely, as I missed the reappearance of 75 Tauri, whilst attempting to observe the bright limb disappearance of the magnitude +4.75 star HIP21029. This was a tad challenging, as to be expected, but I had a go at timing when I thought the star had disappeared from view, which was at 23h44m41.51s.

My next session was between 2:00am and 2:35am on the 6th November, attempting to witness the bright limb disappearance of Aldebaran. I was quite fortunate with this, as a bank of cloud rolled over the area and lasted for about 10 minutes, but luckily it cleared about 10 minutes before Aldebaran was occulted by the Moon. The star really did look piercingly bright by the side of the Moon, and I had a very clear view as the distance between the two gradually decreased. Again, I had an attempt at timing the event, and recorded the disappearance at 02h32m26.95s. As difficult as a bright limb disappearance is to time, it's still a fascinating event to watch. That last little bit of gap seemed to take much longer than I thought to close, and it's quite strange to see a relatively bright star so close to the lunar limb.

I wasn't sure whether or not to stick with it for the reappearance, but the clear skies looked set to continue so I decided I'd make the effort, and I'm glad to say it was worth it. I started observing again at 2:55am, and despite a smaller bank of cloud passing over a few minutes prior to the expected reappearance, I was successful in observing it. I timed the reappearance at 03h24m03.73s. I was beginning to think I was looking at the wrong part of the dark limb area, when Aldebaran finally sparked back into view - the seemingly instantaneous burst did make me jump a little bit! It was a really beautiful sight, with such a slender portion of dark limb separating the star from the illuminated lunar disk. I am a tad tired now though.

I hope others were successful in seeing some, or all, of this event.

Best wishes, Jeff.

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PostPosted: Mon Nov 06, 2017 10:02 am 

Joined: Sun May 11, 2008 6:11 pm
Posts: 3303
Location: Portslade, Sussex Lat 50deg 51min Long 0deg 13mins West
Aldebaran Occultaton by the Moon: 6th November 2017: About 0323 GMT> Used Acuter DS65 (19x) from the back-garden. The sky was very clear. The Langrenus-Vendelinus-Petavius- Furnerius crater-chain were well shown on the terminator. Initially I imagined that there was a mountain peak catching the setting Sun, but then realised that it was indeed Aldebaran reappearing. It was even further south than the large craters mentioned, more inline with the Rheita Valley- Janssen-Fabricius-Metius and the neat pair Steinheil and Watt. [The invisible "dark crescent" obviously tapers towards the poles and was very thin at that point. I was looking too far north to start with, having previously just missed the moment of reappearance of Gamma Tauri but seen it just afterwards the previous evening.] regards maf

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