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  #1  
Old 26-05-2017, 04:26 AM
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Weltevreden SA (Dana)
Dana in SA

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Join Date: Apr 2012
Location: Nieu Bethesda, Karoo, South Africa
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First Light, Intes-Alter MN84, #1

Easy, Pleasey, & Uhh-ohhh

When I learn of a new object Iíve never seen before I feel like a bird dog when it sees a duck pond. So it was with the globulars NGC 5824, Pal 6, and Djorg 1.

We all have our philosophies about looking through a telescope. Some are succinct: ďI saw it, tooĒ. Others are complicated, listing bullet points for exit pupil, Strehl ratios, percentage of light in an Airy disc, the plusses and minuses of brand identities, limiting surface brightness per square arcsecond, airglow, skyglow, and why a glimmer just wonít do to confirm a sighting, it has to be a glimpse and better yet a glance.

For me these are nice but a bit short on imagination. My philosophy is simple:

(a) Itís irrelevant whether I see the object Iím after or not. If I see it, the frisson is wonderful, practically an orgasm for the eye. Yet in the end all I have is a memory and a log entry. The bird dog gets to jump in the pond, duck or no duck. If I donít see it, I end up researching what it is, where it is, why it is, what else is out there with it, and why I donít see it. I learn more from objects I canít see than from objects I can. The bird dog not only gets the duck, it gets a pat in the head and nice big bone.

(b) Thereís always the off chance that some historic harmonic of harmonious scintillation will line up into a perfect optical window at the very moment I peer in the eyepiece and for three seconds I see five magnitudes deeper. Agreed, the chances are probably 1 in 10-7, but people win lotteries, donít they?

So it was that at long last, after two months in boxes on the way to South Africa followed by a four-month part-by-part rebuild, I finally got my Intes-Alter 8-inch f/4 MakNewt out under the stars. Iíve had five straight nights of good to superb seeing at my remote dark site, with three more to come (cross fingers, touch wood, & positive vibes in the direction of the weather forecasters).

This particular MN84 had suffered a hard fall. The meniscus was chipped under all three retainer clips, though none intruded into the clear aperture. Worse, they had not been smoothed with fine sandpaper. Dreams of hairline fractures morphing into the Grand Canyon haunted me all the way to the sandpaper shelf in the paint store. Worse, on removing the parallax rings I found a shallow circumferential dent halfway around the tube under the front ring. The tube was out of round and possible warped. The dent had misaligned the focuser plate by 2.5į from the optical axis. A laser collimator rotated in the focuser traced a 3 mm circle around the diagonal face and 8 mm on the primary. That explained why all the stars in the first tests were little comets aligned parallel to the same angle of 75į from the mirror/secondary axis. Deliverance was at hand in the form of Feathertouch, which has an adjustable baseplate for just this sort of misalignment. Thanks, FT lads, you have my loyalty forever.

There were other problems, too. These kept the friendly local machinist happy for a month. Then the bad news: Recollimating a short-focus reflector after a rehab is a long, frustrating affair. Thereís no room for lackadaisy in a scope designed as an astrograph. The meniscus had a factory-scratched arrow on the side, but the cell had been painted over so there was no mark on which to align the arrow. For awhile life was rotate 30į, put it all back together and test, rotate another 30į and test. But the day finally came when everything lined up the way Intesís optical specs said it should (see image 1). The result is Intes at its best. Eyepieces with a 30mm aperture stop deliver needle-sharp stars all the way across the field with no noticeable vignetting. Familiar nebulae like Orion and Carina showed subtle contrasts Iíd never seen before. Stars hold their pinpoint Airy discs plus a partial first ring at up to 291x using a barlowed ES 5.5mm. Itís hard to find a globular it canít resolve. The well-baffled tube does its job: even at low powers the sky background is noticeably darker than in the unbaffled tube of an 8-inch Intes-Wirth MN86 I bought last year from APM.

In making up the first-light shopping list, I felt like a gambler rubbing his hands with glee at the thought of besting his arch rival with a pair of threes over a pair of deuces. So I chased five newbies for the first time: NGC 5824 GC Lupus, Pal 6 GC Sco, Djorg 1 GC Sco, and Antalova 1 & 2 Sco.
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  #2  
Old 31-05-2017, 01:20 PM
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Tinderboxsky (Steve)
I can see clearly now ...

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Join Date: Feb 2012
Location: Tinderbox TAS
Posts: 424
Thoroughly enjoyed your report Dana. Totally agree with your observing philosophy points and can think of many of my own experiences that accord with this.
A happy ending for the scope refurbishment too.

Steve.
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