Wednesday, March 14, 2012

evaluated 11" donation (Eringate)

Met up with Charles at his shop. We shook down, in two phases, the recently donated Celestron 11" telescope.

Just after my arrival, we pulled it out of the warehouse. We considered setting it up on the "front" sidewalk. But the sky was still terribly bright. Despite using the Celestron SkyScout, we still couldn't spot Venus. Even with the large binocs propped against the wall.

So we kept it inside and did a dress rehearsal. It gave us a chance to review the inventory, document features (e.g. CF tubing, Starbright XLT coatings) and other particulars (Fastar ready). Looked for scuffs, dents, dings; it was dusty. We powered it up and walked through the 2-star alignment process. Both the alt and az motors were working fine. The hand controller seemed fine. But the on-board GPS was clearly struggling under the metal roof. So, we turned it off and headed to the new Shebeen pub to ruminate.

When we egressed from truck, after dinner, given the angle of Venus and Jupiter, I suggested for round two that we try from the backlot. Charles agreed. He opened the big door. We hefted the 29 kilo beast outside. And in short order, we had the 'mount roughly aligned.

Immediately, through the eyepiece, I could see the collimation was quite good. First target: Venus. I showed Charles the "first quarter" phase of Venus. The view was pretty good in the e-Lux 40mm Plössl, without any significant colouring. We slewed to Jupiter. The moons were in a neat pattern, one close on the left, the other three equally spaced on the right. The surface banding was well-portrayed. Initially, the seeing was shaky; a moment later it went rock solid. A very nice view.

For a deep sky target we chose Messier 42. The view at 50x [er, 70x] was fair, with the nebula clearly visible. I found it difficult to focus well on the θ 1 and 2 (theta) stars. Probably a combination of telescope cooling, sketchy seeing, and heat from the roof tops. Charles said he could see green colour; looked grey to me. How many pints did he have?! We bumped the power to 400x [ah no, 560x] with the 5mm Tele Vue Radian. Whoa. Too much. But it clearly portrayed the clumpy nature of the diffuse nebula. Some lumpy darkness. Yes! I centred on θ2 Orionis and defocused slightly. The seeing was definitely badly. But I confirmed the diffraction rings were not circular.

Charles wanted to try some of his gear. While he fetched a 2" visual back, 2" mirror, and 2" wide-field 26mm, I went to Castor. It was easily split in the 40mm. Charles 2" accessories improved the view.

While we never nailed an object in the eyepiece, we agreed that the alignment was fair and the tracking was working well (once we turned it on). This might be a great 'scope for public outreach events. With a proper alignment, it would easy-peasy to use.

Satisfied the telescope was performing well, we packed up. We both agreed the rubber covers on the feet of the tripod were probably not stock. Certainly they were not a good idea.

I wonder where council will send it...


It was later that I confirmed the telescope particulars... We checked a NexStar 11 GPS Computerized Telescope. Given that it's focal length is 2800mm, not 2000, my magnification numbers were off.

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