Thursday, October 30, 2008

occultation mockultation (Pontypool)

Guy offered to conduct a "mockultation" for RASC Toronto Centre members, a simulated occultation of a star by an asteroid.
Instrument: Celestron 8-inch SCT
Mount: Vixen Super Polaris
Method: star hopping
He assigned a target star for us to find. He arranged that the occultation would occur at approximately 9:21 PM. He would beep his car horn when it disappeared and again when it reappeared. We were to capture the times by whichever method we preferred and then be prepared to do the necessary "personal" calculations.

We met in the parking lot of the Long Sault Conservation Area at 7:30 PM. Matti, David, Eric, Mark, Theresa, Frank, and Guy. We had lots of time to set up. I was the first one ready to go. I asked Guy to verify my eyepiece view of the target star. I was at the right spot! I set up my new shortwave radio to one of the CHU frequencies. I tested recording with my yepp digital media device. Everything was ready to go.

8:56 PM. I check both of my portable weather stations. Air pressure was 100.1 kPa. Humidity is between 53% and 63%. Temperature was between 1.1°C and 2.5°C. Eric took a reading with his new Sky Quality Meter: 22.42.

At 9:00 I fired up the drive on the telescope and started the audio recording. The target star in the centre of the eyepiece. The others were chit-chatting and milling about. Guy reminded everyone to be ready! I was already in my seat. I was a little nervous... Even though nothing was going to happen to the star. It was close to 9:20. There was a lot of chatter, excitement in the air, a bustle. And I made a rookie mistake...

For some reason, I decided to change something on my radio or audio recorder. As soon as I walked away from the eyepiece, I thought, "You shouldn't do that. It could happen at any mo--"


Guy had beeped his horn.

I just started laughing...

I made it back to the eyepiece just as Guy honked again.

I was laughing so hard that I forgot to yell "gone" and "back."

What a riot.

We asked Guy if we could try again. "Nope." Tough love.

Well, at least I learned a lot.


Guy wanted us there at 7:30 for an occultation time of 9:21. For me, this was the perfect amount of time. Without rushing, I was ready to go with about 20 minutes to spare. Lots of time to take a biobreak, verify things, fix snags, a relax a little.

The hard part, I can see, would be finding the target star. If it's a mag 11 or 12 in a bright sky, off the beaten track in a constellation, I could see that being a challenge. And if you're on your own, you don't have some one to check and confirm it. You have to be 100% certain. And you need to have good charts! With lots of stars.

The booster battery pack was very low! I had not charged it after the last use. And it's been sitting in the garage during this cold snap. I need to move it back inside for the winter and, obviously, top it up.

My shortwave radio was surprisingly sensitive to elevation. When I set it on the table, the reception degraded; when I held it high over my head, it improved. But it's not line of sight! Where the trees or hillocks interfering? I'll have to talk to Guy about that.

While waiting for the occultation time, I decided to learn a couple more constellations. Using my old planisphere, I located Pisces, below Andromeda and Pegasus. It's big. I reviewed Aries and Triangulum. And then I tried to pick off Camelopardaris (sp?). Very faint stars.

And finally I learned that one mustn't leave the eyepiece... Sheesh. I could have told you that!

And, if you miss it, you miss it. Wow, that would be a downer. If, for whatever reason, you weren't at the eyepiece, and you realise, oh, I'm a little late. Well, you're screwed. Pack up and go home.


Met fellow member Matti this evening. Actually, we had chatted on the Yahoo!Groups when I had made my request for a computer. While he did not offer a full machine, he did offer a large number of computer parts and peripherals.

Matti had called Guy to see if he could get a lift to the Long Sault. Guy had just accepted to give a ride to David. I offered my passenger seat to Matti. Picked him up at 6:15 PM. He's been a RASC member for a long time.

He brought his 15 x 70 binoculars. They offered very nice views. He mounted these on a very interesting cantilevered swing arm contraption with counter-weight by Orion. I believe it is called the Paragon mount.

The view of The Andromeda Galaxy was pleasing. However, the Double Cluster and the Pleiades (Messier 45 or M45) were breath-taking. Very three dimensional!

Matti asked for my help locating the target star. I helped him get to centred on the area.


9:41 PM. Humidity was holding steady. The Sky Quality Meter showed 20.58.

After the mockultation, I decided to target some items in the east. I looked at γ (gamma) and λ (lambda) Aries. Nice double stars.

λ Aries appears to have a separation of about 15 to 20 arcseconds. Haas says 36.7" (in 2003). The main star is yellow. I can't tell the companion colour for certain. It seems blue with averted vision and dark orange under direct viewing.

γ Aries looks like 2 eyeballs. White. Same brightness. Haas says the separation is 7.5" as of 2004.

10:09 PM. Tried for NGC 772 in Aries. It is just a smudge in the wide field eyepiece. No time to sketch it...

Guy was also casually viewing the sky. He offered a spectacular 26x view of the Andromeda galaxy (Messier 31 or M31). Wow! Very nice seeing it with Messier 32 (M32) and Messier 101 (M101). [ed: Er, I think I meant Messier 110 or M110.]

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