Sunday, November 20, 2016

Occultation of Aldebaran, October 19, 2016

Finally during this series of 49 consecutive lunations where someplace on Earth will see our Moon occult Aldebaran, the weather cooperated when Aldebaran was occulted over my girlfriend's home in South Bend, Indiana early on October 19.

Illinois astronomer Curt Renz's predictions for Chicago.

Late that Tuesday night (October 18), as Aldebaran rose above my girlfriend's garage, I could see it naked eye, even though the Moon was closing in. Around midnight, however, the light from the nearby Moon was just too overwhelming to see Aldebaran naked eye, even by blocking out the moonlight.

Nearing 1:00 AM EDST, I went outside to the small enclosed yard between the house and garage and set up a borrowed 8" Dob that I used for the observation. Upon my first look through a 20mm eyepiece (60x) showed Aldebaran in view with Luna.

Not knowing an exact immersion time, I monitored the pair for the next half hour. As immersion was imminent, I let my girlfriend Dawn have a few looks. I wasn't going to attempt getting the exact time of immersion, but I did want to be watching as the star disappeared. After Dawn had one last look, I took one last image with my phone. As I tried to put away my phone, I fumbled with my phone, and missed the immersion.

I knew I had around forty minutes until emersion, so I warmed up with a cup of coffee, and for the first time that night, consulted Curt's predictions that I listed above. I also found his predictions for the 1 & 2 components of Theta Tauri, which had both been occulted earlier in the night. Even though I had missed those two occultations, I was able to track down the pair when I went back out to the telescope.

Waiting for emersion.

I no longer remember what time I observed Aldebaran emerging from behind Luna, but I had been watching intently where I expected it to return for several minutes. I was amazed as Aldebaran appeared and quickly brightened, happening in less than a tenth of a second, but very noticeable and striking. After Aldebaran emerged, I let Dawn see it again, before obtaining images.

Once emersion had been observed, there wasn't much reason to stay too long after. I finished up my imaging for the night, packed my equipment, and went inside. I apologize for the delay in posting this report, but it's been a hectic month, and really almost a year now of personal instability, for a variety of reasons. I was glad to escape for a couple of hours, and observe my first occultion of Aldebaran during this series.

Thursday, February 19, 2015

Mare Orientale, Finally

My previous post was about observing the the celestial western limb of our Moon with both favorable libration and illumination. I haven't been as lucky with the celestial eastern limb. Twice this year so far, in January and February, I've managed to observe Mare Orientale with favorable librations.

After waiting so long for a good phase and libration to see Mare Orientale, my chance came while I was at work the morning of January 16. This observation was during my 15 minute break, and I had to get out to my car, get out my telescope and set up, and try to get images as fast as I can. While my phone doesn't have much of a problem taking lunar pictures when the Moon is near full, it likes to overexpose the limb during the crescent phase. I had to combine my neutral density filter with my #80A blue filter, and turn down the exposure setting on my camera, just to try to compensate. It was cold, and the Moon was still low in the sky, with terrible seeing conditions. Saturn, though, was visible below the Moon, if you drew a line connecting the horns of the crescent, and followed it straight down.

In brief visual observing, I could see Lacus Veris, Lake of Spring, and beyond it, Mare Orientale on the limb. Being rushed, though, I didn't get any images worthy of posting if this weren't such a challenge just to get the necessary phase and libration. I'll let the photos tell the rest.

Then on February 13, we finished early at work, and were sent home at 3:00 AM. At first, I wasn't happy about it, but before I left work I remembered that it was a great morning to see Mare Orientale again, and the sky was clear. I couldn't wait to get home and observe.

Although I'd seen Mare Orientale in January, that was a very brief observation in the parking lot at work, with bad seeing conditions. This time the libration was even better for observing the Orientale region, and while seeing still wasn't very good, I had the time to wait, and it did improve a little as the morning progressed. Unfortunately, it was very cold, 1° F (-1° F wind chill) in Valparaiso, so I took several warm up breaks.

Visually, I was very pleased with the view, although I didn't manage to improve much upon my images from last month.

I was about to end the observation, but realized that I hadn't really observed much outside the Orientale region, so I scanned the lunar surface to see if anything interesting stood out. I then realized that there was something conspicuously absent. In the far south, near the terminator, I noticed a crater, later determined to be Casatus, that was surrounded by darkness, even on the day side of the terminator. I can't find much information about Casatus and surrounding craters other than size, but based on this observation, I have to think the region is in a basin deeper than the surrounding terrain.

Part of the eastern rim of crater Klaproth can be seen just above Casatus, but the northwest of Casatus is deep in shadow, even though it is on the day side of the terminator.

I love observing our Moon. No matter how well I think I know its surface, I always get surprised by something new, or seen in a new light, or in this case, a new lack of light.

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.