Thursday, September 21, 2006

20060921 - Getting the hang for the crescents

Session Name: 20060921.0400 at Carl Schurz Park
28d 14h 46m Last Crescent Moon

EZ in Binoculars - Fujinon & Taks
05:57am EDT to 06:40am EDT

Moderately EZ with Naked Eye
05:58am EDT to 06:22am EDT

25h49m from New Moon 2006 Sept 22 7:46am EDT

Okay. Some like the challenge of a par 5 with a range anywhere between 435 and 630 m (476 and 690 yds.) Me? I love the challenge of collecting photons from outer space, a range of light seconds to millions of light years. Where a golfer chooses among woods, irons, and putters to do the right job, I choose from my supply of binoculars, reflectors, and refractors, each designed with a special purpose.

The last crescent before New Moon does not require a driver. Nope we're talking the short game, a small refractor or better yet binoculars are satisfactory to catch photons that left the lunar surface about 1.35 seconds earlier. My tripod was topped with my reliable Takahashi 22x60 binoculars and Charlie had his trusty Canon 15x image stabilized bins.

The slender crescent Moon was spotted with in the handheld Fujinon 7x50 bins at 05:57:04am EDT at an elevation of 1°01'. The first image above leads to a marked up version showing where Moon rose relative to the Sun. I calibrated my watch with eBay. My watch differed from them by being fast 1m 04s so with this corrected for the timestamps in my logbook.

It wasn't really difficult to predict that this crescent was going to be easy. And it was. Elongation was 10°47' and the ecliptic stood very steep so that the Sun was still well below the horizon when the Moon rose. I am surprised by the low altitudes we are able to see at. Moon's age 25h49m in terms of absolute age relative to the New Moon - pretty easy.

The crescent was "lumpy" exhibiting an uneven brightness. Two bright patches on the crescent between 5:30 and 8:30 measured along the limb were made from a darkening about 6:30~ish. These were the remarkable features that I noticed in the bins and naked eye. It was this aspect that impressed me most and exceeded that threshold of contrast that allows me to detect it. When I turned to talk to Charlie it would allow me to recover Moon from a brightening sky.
The horns reached to 4:30 and 8:30 ~9:00 and with those bright patches just mentioned I could see with certainty that the crescent was tipped to our right.

It was exciting to watch the crescent until I could see it no longer. I lost it again this month by a similar action: turning away my attention at that critical end so now I know to stay in the eyepiece until I lose it from gaze not inattention. Today as I said I turned to speak to Charlie. Leading up to the time I lost it I had done the same thing a couple of times, that is taking my eyes from the bins. But each time I looked back into the EPs, I relied on establishing Venus and then looking off for the crescent. It would be a moment, my eyes adjusted, and there Moon appeared still maintaining a contrast that was good enough for me to see our neighbor. I knew these were frail moments as I appreciated this small strip around the 7:30 ~ 8:30 that would catch my eye. I see you. I thought to myself maybe this is what the record holders experience when they catch these slender crescents just barely visible - and yet they've done it without the crutch of Venus or any other nearby astronomical landmark. Bravo to them. And practice, practice, practice for me when the opportunity comes.

Checkout Charlie's blog for a report of this event.