This Gun's Out Of This WorldPosted By Thomas Dey |
Creative --- although technically ... ALL guns are forged from meteorites.
Posts Made By: Thomas Dey
December 29, 2015 05:45 PM
Forum:
Off Topic Discussions
January 3, 2016 03:38 AM
Forum:
AstroMart FAQ
Can't change profile picture.Posted By Thomas Dey |
There may be an implicit max file size req as well ... if it is .jpg should load OK. I have found that images on many sites generally need to be a tad smaller than max allowed file size. Probably because the "overhead" related to the imbedded text etc. eat up a bit of hidden space. Just guessing though! Tom
January 5, 2016 02:38 PM
Forum:
Meteorites & Meteors
Fireball seen in Canton, MAPosted By Thomas Dey |
Cool! Anytime I'm observing, I hope a meteorite lands right at my feet ... without damaging my equipment or hurting me ... big and valuable. I sell it, become famous and buy more telescopes with the proceeds. It hasn't happened yet; so I'd better do a lot more observing! Tom
January 9, 2016 04:50 AM
Forum:
ASTRONOMY
Why do i see green ?Posted By Thomas Dey |
Hi david, attached self-demo that helps. Open that image and crank your screen brightness all the way up. Stare at the magenta circle for a minute and then look at the white circle down below. It looks green. This is closely related to (the inverse of) "Dark Adaptation" familiar to us Deep Sky observers. It is caused by BOTH differential chemical depletion of the red (X) and blue (Z) receptors in the cones AND depletion of the associated neurotransmitters (awaiting "reuptake"). You can do that with any of the other primary colors and their compliments. This also relates to going into a DARK movie theater from sunlight and being temporarily blind and the inverse affect of being dazzled upon emerging a couple hours later. We astronomers typically associate Dark Adaptation only with the rods --- but it substantially affects the cones too! Ummmmmm... when I was 17, I worked at the Boynton Center for Visual Science at the University of Rochester. Ran experiments there and constantly talked physiological optics with the teachers and grad students. The Eye is an extraordinary instrument! Tom Dey
January 9, 2016 05:01 AM
Forum:
ASTRONOMY
Why do i see green ?Posted By Thomas Dey |
Good! I just looked at dan's link there and it is dramatic. By extension, the same sort of thing can be done with any color leading its compliment. And that's also why artists like to work in compliments --- because they mutually enhance colors, making them feel "electric." Come to think of it --- why complimentary-colored double stars look SO colorful! What we call "color contrast." On top of all that ... color perception and discrimination vary wildly among people, just as do their senses of taste. Tom
January 15, 2016 04:51 PM
Forum:
Digital SLR AstroPhotography
M37Posted By Thomas Dey |
Nice images! I did film long ago and burned out on effort and equipment. Want to ease back in with reasonably modest DSLR. I like that your images look similar to looking thru a scope. Tom Dey
January 18, 2016 03:51 PM
Forum:
CCD Imaging and Processing/Deep Sky
M 101 and comet C/2013 US 10 CatalinaPosted By Thomas Dey |
Very nice indeed in every respect! Great technical; aesthetic; Event; wide field; framing. I of course like how both tails and coma are captured. Thanx for sharing. Tom Dey
January 23, 2016 06:55 AM
Forum:
Off Topic Discussions
More BS...Posted By Thomas Dey |
Hi Rod, The overarching questions regarding life and further - technological civilizations ... is indeed interesting. We're here, but that proves nothing regarding probabilities. So extraordinarily unlikely to virtually guaranteed (life and technology) it totally unknown. My plain opinion is that life here and out there is essentially guaranteed ... but technology is sporadic at best. So we see nothing other than us - yet. Further opinion is that "intelligence" is quickly self-snuffing ... because things like Atomic Bombs, bio weapons, etc. - although kinda sophisticated - are just way TOO easy to make and use. So sufficiently dumb animals are the only ones that can last for millions of years twixt big asteroids, SN wipe outs, etc. We astronomers are able to see a hell of a lot and all of it looks "natural." But with the gazillion stars, planets, universes (?!) must be a lot of thinkers out there. But dilute and far away in space and time. Chance of finding others is Zippo. Tom
January 24, 2016 12:18 PM
Forum:
Telescope Making
41.75" (1060.45mm) reflectorPosted By Thomas Dey |
Wow! Hi Charles and Dave. Diam Big but it's the Thickness of your Solid that gets me! Like Dave, I've dealt with big stuff at work, but only the testing for me and watching other people man handle them. At home I stared at meter+ a couple of times and finally settled on a finished and coated fastish light-weight 36, which still awaits the mount... That one is pretty close to feasible (effort and $) because "all I need" is the Whiffle-Tree and plywood to build the Dob. I already have all the other parts. Even with creative mounts, the big stuff is still way non-linear function of size by any metric you choose: cost, effort, time, weight, logistics, materials, available shops, testing, coating, ladders, comfort of use, tracking, storage, transport, maintenance, thermal stabilization, danger...? BUT it all becomes worth it when you finally go operational and approach the eyepiece or camera --- holding your breath and hoping for the best! The Tracking for Imaging not to be short-changed for something SO massive: Three approaches to consider that could make that aspect less stressful: Mallincam, CCD TDI, Night Vision streaming video. Keep us posted as things progress! Tom Dey
January 25, 2016 06:40 AM
Forum:
Telescope Making
41.75" (1060.45mm) reflectorPosted By Thomas Dey |
Charles, thought of something else: Do you know what the material is? From your picture it looks quite clear. In order of increasing value and utility would be "white" crown, Bk7, Pyrex (aka Borosilicate), fused silica, ULE. Older Pyrex and fused silica have bubbles; older ULE is blueish. New generation are quite clear and free of inclusions. If you lucked into fused silica or ULE, thermal behavior could be quite good, even exceptional. ULE CTE is nearly zero at room temp. i.e. it is a function of temp tailored to be identically zero AT operating temp. There are easy ways to ID the exact material if even only one surface is flat and polished. Equipment to do that you probably already have. Tom
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