Friday, April 26, 2013
Pictures of a Cloudy Partial Eclipse, Friday April 26, 2103
Before heading to bed in preparation for the mornings partial eclipse, I checked the sky. After the cloud of the morning the sky was brilliantly clear. Arising at 4:45 am this morning the sky was still clear with a few fluffy clouds about, perfect!
Of course, as soon as I had the telescope set up (with my little 4" Newtonian for easy of use), the clouds started coming over. I started imaging when the bottom of the Moon was already visibly dark from the penumbra, so I don't have a good "start" comparison image (hey getting up at 4:45 am after a 5 am rise for the Dawn Service the previous day was pretty good I thought). Have a look at the "before" image from last years penumbra eclipse for an idea of what the "before" should have been, a nice, more even brightness.
As the eclipse progress the clouds started coming more frequently, getting darker and with fewer gaps. With the unaided eye the darkening was obvious, although confined to a thin sliver at the Moons south.
The problem I had was that the Canon does not have an fixed time setting below 1 second, far too long for exposures with my unguided Newtonina, and over exposing everything except perhaps ASA10. I I had to stick with autoexposure Which is fine if there are no clouds about, but for the latter images cloud was always over the Moon, messing up the exposure so that the darkening on the southern limb is less than what I was seening with my eyes.
9 minutes before maximum eclipse a thick band of cloud came over and squatted there until past maximum . At this stage I packed up and went inside.
After packing up, putting telescope away and so on. I went out side for one last check, and the Moon appeared through a sucker hole, as if to mock me. The darkened south pole was an obvious notch on the base of the Moon.