Jupiter - Page 7 - PeachParts Mercedes-Benz Forum

pj67coll · #91 01-16-2019, 12:30 PM

Quote:

Originally Posted by Botnst

Update!

The observatory is progressing. I welded a plate to the pier to hold a car battery instead of running off a dry cell 12v battery pack. Still working on pier.

So, ...... I set up and polar aligned the mount. Ran through the controller menu. Chose 1-star alignment. Mount skewed scope 180 def from target star. Hmmmmm.

Turned off mount. Checked polar alignment. Carefully went through set up procedure referring to manual. Selected 1-star align. Slewed 180 degrees off.

Turned off mount. Unplugged from battery. Waited a couple minutes. Redid everything. 180 off, damn.

Went to CloudyNights and laid bare my soul. Turns out I had the telescope mounted BACKWARDS! Shyte!

Been cloudy ever since.

I was thinking you'd got a mount set up for the Southern Hemisphere. But put on backwards? Hmmm. Perhaps Astrology is more your line

- Peter.

Botnst · #92 01-29-2019, 04:03 PM

I could tell, 180 deg off, that it was something really simple and pretty stupid. So I METICULOUSLY went through the manual and set-up and alignment routines. Three times.

At that point I at least recognized that I couldn't see my own ignorance. I knew it was going to be something really, really basic. I just couldn't see it!

Dang.

But I had that sucker up and running with my 6" reflector on it several nights ago. It works beautifully. much, much better (for me) than the dob. I haven't installed the rings to let me rotate, but really, just slightly loosening and gently rotating barely shifted alignment.

After I work with the 6" a few months I'm gonna put it back on the dob and try mounting the 10" Zhumell. I can hardly wait!

cmac2012 · #93 01-29-2019, 05:03 PM

A buddy in when I was in my 20s told me about grinding his own concave lens. Relatively simple pattern using gringing compound. I forget the details. He said it worked pretty well but he no longer had it. He did bring over an inexpensive 2 inch refractor telescope, had a crude hand operated tracking mechanism that was better then nothing. I was amazed that you could see Jupiter's red spot (not red in this scope) and some of its moons as well as Saturn's rings.

Botnst · #94 02-01-2019, 02:27 PM

Stellafane is a great starting place for diy telescopes. Mirrors: https://stellafane.org/tm/atm/index.html

Botnst · #95 02-09-2019, 07:11 AM

Or you can buy mirrors and use sonitube properly sized for mirror & focal length. If you’re carpentry skills are adequate you can build a nice mount, too! https://stellafane.org/tm/dob/mount/cradle.html. I’ve seen some beautiful custom designs, artistic cabinetry with exotic woods. Look online for examples. If I lived in California near the foothills this would be a great mount for a big beautiful telescope. And Mexico can pay for it!

Maybe next years’ project for me.

pj67coll · #96 02-09-2019, 07:38 PM

There are some beautiful home made telescopes for sure. True works of art.

- Peter.

Botnst · #97 02-16-2019, 03:21 PM

I finished fabricating my pier. It’s made from a 7’ section of thin walled 6” tubing. With my tractor auger I dug a 48” deep hole 12” in dia. This will give me 3” around the tubing for concrete, which will tie to a 4” thick 2’ dia pad. The pad is for stability only.

Online I found an engineering website which computes the deflection angle of a hollow cyl, given material, wall thickness, diameter and anchored length also the force applied. Cool! On CloudyNights I found a discussion about deflection angles on piers and it’s basicly anything an arc-second or less is good and slamming the pier with a 5# hammer is a good simulator. So I gave it the dimensions of my tubing and did the math for a 5# hammer swung at arm’s length, gave a ballpark estimation on acceleration (faster than gravity) and found the deflection angle was well below the threshold.

The soil conditions bother me so I went nearly twice the recommend depth and lots of concrete. Also, I welded a car battery tray to the tubing. Mount runs off 12v DC. When the cement cures I begin building my roll-off shed.

pj67coll · #98 02-16-2019, 11:41 PM

Deflection angle?

- Peter.

Botnst · #99 02-17-2019, 09:38 PM

Smack that puppy on the side with a 5# hammer and see how far it jumps.

pj67coll · #**100** 02-26-2019, 07:08 PM

Quote:

Originally Posted by Botnst

Smack that puppy on the side with a 5# hammer and see how far it jumps.

Sorry. I don't see the relevance. You're not smacking anything around with a hammer when you're observing so what's the point?

- Peter.

Botnst · #**101** 02-28-2019, 07:58 AM

If astrophotography comes into play, you want the pier deflection angle to be less than the size of a camera pixel. That works out to be a half arc-second (somebody on cloudynights did the computation). Why 5#? Mostly arbitrary. The rotation of a long telescope on the pier would introduce a torque equivalent to less than 5# so, that became the arbitrary threshold. The taller the pier, the more important it becomes.

Botnst · #**102** 03-05-2019, 04:55 PM

I set the pier in concrete today. Eight 40# bags. Yikes! Hope I get clear weather next week.

t walgamuth · #**103** 08-07-2019, 11:37 AM

Jupiter is out again. Now it is in my southern sky in the evening. Big and bright. I looked it up and Saturn is also scheduled to be seen soon but later in the night I think.

pj67coll · #**104** 08-07-2019, 12:02 PM

Quote:

Originally Posted by t walgamuth

Jupiter is out again. Now it is in my southern sky in the evening. Big and bright. I looked it up and Saturn is also scheduled to be seen soon but later in the night I think.

If it weren't so damm hot around here I'd be out more looking at these things. My wife and I really want to get the hell out of here. Hopefully we can find a decent place up north when we retire in five years. One of my first acts will be to construct an observatory of some sorts.

- Peter.

Dubyagee · #**105** 08-07-2019, 12:03 PM

I saw Jupiter last night while walking the dog. It was bright