Wednesday, September 28, 2011

1484e 2011/09/28–29

1484e 2011/09/28–29 22:05–22:50 EDT Foxmead POD 8–3 28cmsc

First light of 28cmsc on Celestron CGEM, Clearing was quite unexpected, but I decided to give it a try. It soon became very hazy again, but I managed a few observations.

Jupiter: 127x and 254x Seeing poor.

Deep sky: M45 @ 127x

Double stars: Almach @ 127x

The whole mount needs to be rotated to the right to get closer to Polaris. I also need to loosen the azimuth motion so that I can fine tune the alignment, which needs to be done in daylight when I can see what I'm doing. Things are a bit cramped in the POD with the GEM. The mount is absolutely silent when tracking, but fairly noisy when slewing. I also need to adjust the William focuser, as it is slipping under the weight of the big Nagler eyepieces.

Temperature = 14° C

2011 September 28

The dovetail plate to attach the Celestron 28-cm SCT to the Celestron CGEM mount arrived from Astronomics this morning. I tried it out in the CGEM's saddle then installed it on the tube with the supplied bolts. I was glad to see that it installed with four bolts, not the three I had thought. With two bolts snugged down on both front and rear cell, it seems very solid, and much better than a Vixen dovetail would have been.

I then went on to Step 1 of the Great Telescope Transformation: removing of the Explore 127-mm triplet apo from the mount, and storing it in its case. Though the case looks very nice, the scope must be in a very specific orientation and configuration to fit in the case, not the same as on the mount at all. I also removed the two 11-pound counterweights. I'm now recuperating before tackling the next steps:

2. Removal of the Orion Sirius mount.
3. Installation of the Celestron CGEM mount and counterweights.
4. Installation of the Celestron 28-cm SCT.
5. Balancing and testing.
6. (After dark): Alignment of mount.


Steps 2 through 5 were accomplished in stages this afternoon. The scope is now riding on its new mount, balanced and ready for the next clear night. The CGEM came with a 17 pound weight and this, along with an 11-pound weight from the Sirius, almost exactly balances the 27.5 pound tube plus finder, dew shield, William focuser and 2" diagonal, and Tele Vue 22mm Nagler eyepiece. If I add camera or binoviewer, I may need an additional counterweight.

Sunday, September 25, 2011

2011 September 25

I performed surgery on my CPC1100 today, removing the optical tube assembly from the fork mount because the motors have ceased operating after a nearby lightning strike a few weeks ago. I removed the cover plate from one arm, sprung the arm, and removed the tube. I've asked Blake Nancarrow to take a look at the CPC1100 mount to see if he can troubleshoot it.

I recently bought a Celestron CGEM mount to carry the 28-cm optical tube, and am awaiting a Celestron dovetail plate so that I can attach the 28-cm tube to the CGEM. The plate is on its way from Astronomics in Oklahoma, who had one in stock. I've also ordered a "wide-to-narrow" adapter plate from Orion so that I can use my Vixen dovetail scopes on the CGEM. This one mount should be able to carry all my various telescopes.

The CGEM has an interesting feature I was unaware of: you can polar align the mount accurately on _any_ star in the sky. This will be handy since I can't see Polaris from my POD's location. The CGEM also has the same basic interface as the NexStar and CPC, which I find more versatile than the hand controller on the Orion Sirius mount. It has more user-definable objects and a wider variety of named objects. I also really like the Celestron's "identify" feature which lets me explore the area I'm pointing at. The Sirius will identify a single object, but doesn't generate a list of the five nearest objects.

My main reservation about using the CGEM in the POD is that it will take up significantly more room, which is limited to start with. I've been finding with the Explore 13-cm on the Sirius that the POD is cramped. The 28-cm SCT tube will be a lot shorter, but a lot fatter and somewhat heavier, requiring more counterweights. We shall see how well it works.

Sunday, September 11, 2011

1483e 2011/09/11–12

1483e 2011/09/11–12 20:30–21:10 EDT Foxmead POD 8 13cmrr

Aligned on Altair and Alpheratz. Could just barely see Alpheratz because of Full Moon and hazy atmosphere. Confirmed alignment by returning to Altair, then viewed:

Double stars: Albireo @ 38x.

Moon: @38x.

DSO: M11 @ 38x.

Pointed to Polaris: still clearly off pole, but at least GoTo is working well.

22:30–23:40 EDT Foxmead POD 8 13cmrr 8cmrr

Resumed observations at 22:30.

Jupiter @ 190x (10mm+TV bino), 115x (25mm+Orion bino), 230x (12.5mm+Orion bino). Trying various binoviewers (Tele Vue BinoVue and Orion) on Jupiter. Surprisingly, the nicest image was with the Pocono 12.5mm orthoscopics and the Orion Shorty Barlow screwed into the Orion binoviewer. This combo was also much lighter than the TV combo. I began observations of Jupiter around 22:40 when it was still below 15° altitude: lots of colour fringing! As it rose, the fringing diminished and the seeing improved. Initially theimage looked "gritty" but then finer detail came into view. There was a transit of Io's shadow beginning at 22:56. I first could see the shadow definitely at 23:08, appearing like a condensation in the SEB.

Also looked at Jupiter and the Moon with 80mm GoScope @ 18x and 58x. View of Moon was spectacular. Jupiter's moons were clear and 2 main belts visible.

Star test: I did a star test on Alpheratz using the 10mm+TV. Bright outer ring on both sides of focus, but inner rings are very round and even, just a hint of diffraction in focus. I then looked at Almach with 10mm+TV: beautiful colour contrast of bright gold and pale blue.

I parked the scope at the end of the evening. We'll see how the alignment holds up next time.

This is probably a good example of what to do on a hazy Full Moon night: tinkering with mounts, eyepieces, and binoviewers.

Temperature: 13°C. Hazy but not damp, no dew.

Friday, September 9, 2011

1482e 2011/09/09–10

1482e 2011/09/09–10 20:30–22:00 EDT Foxmead POD 8 13cmrr

Aligned Sirius mount on Altair and Alpheratz. Alignment was quite a bit off, probably because polar axis isn't pointing exactly at north celestial pole. I will try adjusting the mount in daylight, as it's too heavy and awkward to do in the dark. I left the scope pointing at Polaris at the end of the session.

Moon: Gassendi and Artistarchus well placed, just as described in my article this week on
Observed with new 13mm Tele Vue Ethos (73x), and with Orion binoviewer with two 25mm Plössls and 2x Shorty Barlow in cell attached directly to nosepiece (∼150x).

Double stars: Almach: Blue secondary just barely visible at 38x, very nice with binoviewer (∼150x).

Observations discontinued due to bright Moon, poor seeing, and rising fog.

Temperature: 13°C