Friday, December 26, 2014

My Best Look Ever at the Celestial Western Lunar Limb

How many times have we heard or read that the half Moon is the best time for lunar observing? I know the terminator is most striking at that time, but I really hate that advice. When asked when to best observe the Moon, I answer that it depends what you want to see. Only observing Luna near the half phase limits what can be observed, and I like to explore the entire disk, and when libration allows, sneak peeks of the far side.

On the night of December 6-7, the Moon was 99.8% illuminated when I started observing, but was already past full, so the celestial western limb was starting to show shadows as the Moon began to wane. With the Moon so recently past full, and a libration of over six degrees in latitude, I saw features along the limb that I had never seen before, or at least had never seen well.

I observed over the course of many hours, and watched as features near the terminator disappeared into lunar night. While atmospheric transparency was never great that night, toward the end of the observation it was terrible, and water vapor in the air started turning the images very soft.

The next time you think, "I'm not going to observe tonight because the Moon is full," remember that you might just see part of the lunar surface you've never seen before.

Thursday, December 18, 2014

Galilean Moon Observation- November 30, 2014

As usual, I'm late in posting. Thanksgiving weekend was mostly cloudy, but early that Sunday morning was finally clear. I went out to observe the Jovian system from about 4:00 AM until about 6:00 AM.

Observing notes: November 30. 2014

Weather- 3:37 AM CST 51°F- 46°F wind chill
5:17 AM CST Salt Creek Commons 52°F- 46°F wind chill
Wind- South 12 MPH; 24 MPH gusts
Dew point 48°F

Here are Curt Renz's prediction times for Galilean events that morning.

Just missed Io shadow transit- ended 4:14 AM. Was observing before end of shadow transit, but not looking near limb, where shadows can be hard to detect.

Bad seeing, and got worse.

Watching as Europa separates from Jupiter's disk, after emerging from occultation.

All images are from my Galaxy SIII phone, afocally, and thus the poor quality. Also, Callisto, being so much farther from the Jovian disk was hard to image. I only captured it in a few images, seen below.

Io transit egress- first observed 5:25 AM CST.
Io separation- first observed 5:30 AM CST.

And that wrapped up my first prolonged Jovian observation since late spring.