RE: [Utah-astronomy] Re: Starpartyetiquetteforcrumbcrunchersandparents
I think there is a greater probability of a dobsonian telescope catching fire than starting a forest fire, which would really hurt the wallet. My telescope manuel says that the UTA can catch fire if pointed at the sun. I always use caution when collimating the scope in the daytime. Debbie
[Original Message] From: Wayne Reese <waynereese@qwest.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Date: 9/30/2004 2:20:55 PM Subject: RE: [Utah-astronomy] Re: Starpartyetiquetteforcrumbcrunchersandparents
I bought an F-4 canopy from Smith and Edwards last year to build a flight simulator for my Grandkids. They (Smith and Edwards) said that they would have had a larger selection, but the Sun shinning though one canopy started a fire in their yard. I know this isn't telescope related, it does demonstrate a sun caused accidental fire.
Wayne
Ps as long as I'm using band space, Dale Hooper, it looks like I moving to 359 N 1000 E, Hyde Park, anywhere near you?
-----Original Message----- From: utah-astronomy-bounces+waynereese=qwest.net@mailman.xmission.com [mailto:utah-astronomy-bounces+waynereese=qwest.net@mailman.xmission.com ] On Behalf Of Brent Watson Sent: Wednesday, September 29, 2004 10:36 AM To: Utah Astronomy Subject: RE: [Utah-astronomy] Re: Starpartyetiquetteforcrumbcrunchersandparents
Starting a fire is just as unlikely off axis as well. The light cone doesn't change much off axis, and most folks don't park their scopes within a focal length of tinder. If they did they wouldn't have much of the sky visible. You must also have a fast enog=ugh scope to start the fire. The focal ratio required to do this is much smaller than most scopes. You really have to try to do any damage. The reticle in a Telrad doesn't catch fire, it just melts - a much lower temperature is required to melt mylar than to burn something up.
There is a tale that one of the ancients started the sails of his oponents ships on fire by stationing his troups around the bay with individual mirrors, and then having them focus their mirrors on the sails. It has been shown that this too is very improbable.
Brent --- Chuck Hards <chuckhards@yahoo.com> wrote:
Lisa, read my last post. Yes, you CAN start a fire with a telescope mirror, it's just unlikely on-axis unless tinder is very near the focal plane.
Eyepieces left on a chart table can do the trick, too, and tell all those folks with melted Telrad reticles that the sun isn't a problem.
I would like to see John's calculations, assumptions.
I have several large mirrors and am happy to demonstrate the off-axis danger on a sunny day.
--- John and Lisa Zeigler <john@johnstelescopes.com> wrote:
Ya, John did the physics of it for me last night and figured out exactly what diameter mirror at what focal length you would need to start a fire. Let me tell you, it aint going to happen! Sometimes its difficult living with an over analyzer. I just meant it figuratively.
Lisa Zeigler www.johnstelescopes.com www.mirrorkits.com
-----Original Message----- From: Brent Watson [mailto:brentjwatson@yahoo.com]
Sent: Wednesday, September 29, 2004 7:52 AM To: Utah Astronomy Subject: RE: [Utah-astronomy] Re: Star partyetiquetteforcrumbcrunchersandparents
The forest is no more at risk from a alrge scope than from a small scope. It is pretty hard to get enough energy out of a scope and across a distance large enough to do any damage. The image, and the energy in the image, spread out very quickly and become a non-problem.
Brent
--- John and Lisa Zeigler <john@johnstelescopes.com> wrote:
We have a 1/4" plywood shield over our mirror on the truss tube Dob. It sits about an inch over the mirror on three screws from the mirror cell. This protects it from wind, rain, dust, and the forest from harm.
Lisa Zeigler www.johnstelescopes.com www.mirrorkits.com
-----Original Message----- From: Debbie [mailto:astrodeb@earthlink.net] Sent: Tuesday, September 28, 2004 1:17 PM To: Utah Astronomy; Utah Astronomy Subject: RE: [Utah-astronomy] Re: Star party etiquetteforcrumbcrunchersandparents
That is another reason I don't like to leave my scope up during the daytime, besides animals getting to it. A big dobsonian could cause a forest fire or blind someone.
Debbie
[Original Message] From: Patrick Wiggins <paw@trilobyte.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Date: 9/28/2004 11:10:18 AM Subject: [Utah-astronomy] Re: Star party etiquette forcrumbcrunchersandparents
I seem to remember many years back a star party up by Kamas where Brent's monster scope ended up catching a frisbee or two. But then I seem to also remember that later in the day the scope became a chimney
when sunlight found its way to the primary mirror and smoke was seen emanating from the tube...
Patrick
Chuck Hards wrote:
Don't be so sure; I've seen many telescopes
(present company
excepted, of course) that may as well have been trash-cans...
--- John and Lisa Zeigler <john@johnstelescopes.com> > > Solid tube Newtonian telescopes, no matter how > much they look like > > trash cans or basket ball hoops are not for > throwing things into..
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This is why in MY Dobson kit, right there next to the eyepieces and extinguisher, you will usually find a package of A&R hot dogs. I figure if my scope goes up, it won't be a total loss. ;) After this discussion, I am going to Kirkhams to have shoulder straps made for my 12" Dob, so I can carry it with me when I go hiking in the hills. Never know when I might get lost and need to start a fire. I know I can always find something to kill and eat, and while I am sitting around the smoldering scope, roasting prairie dogs and pot guts, I can always signal search aircraft with what's left of the mirror... ;) Quoting Debbie <astrodeb@earthlink.net>:
I think there is a greater probability of a dobsonian telescope catching fire than starting a forest fire, which would really hurt the wallet. My telescope manuel says that the UTA can catch fire if pointed at the sun. I always use caution when collimating the scope in the daytime.
Debbie
A few years ago, Allen was working on the big scope while it was in the trailer. He had the primary cover off, but the secondary was covered. At one point, he smelled a fairly strong burning rubber smell, looked up and saw the secondary cover beginning to smoke (It is a dense foam material). After he rescued it, and covered the mirror, we determined that we could remove the secondary, put in a rotisserie spit (operated off of batteries recharged by solar power) and roast meat during the day at a star party. If we plan it properly, we should be able to set up a concession stand and at least pay for our travel expenses. Of course, it will double our travel time since we will have to keep stopping to gather road-kill on the way to the star party.... Jo At 05:31 PM 9/30/2004 -0600, you wrote:
This is why in MY Dobson kit, right there next to the eyepieces and extinguisher, you will usually find a package of A&R hot dogs. I figure if my scope goes up, it won't be a total loss. ;)
After this discussion, I am going to Kirkhams to have shoulder straps made for my 12" Dob, so I can carry it with me when I go hiking in the hills. Never know when I might get lost and need to start a fire. I know I can always find something to kill and eat, and while I am sitting around the smoldering scope, roasting prairie dogs and pot guts, I can always signal search aircraft with what's left of the mirror... ;)
Guy, you kill me! Thanks for the laugh, I needed it! Lisa Zeigler www.johnstelescopes.com www.mirrorkits.com -----Original Message----- From: diveboss@xmission.com [mailto:diveboss@xmission.com] Sent: Thursday, September 30, 2004 5:31 PM To: Utah Astronomy Subject: RE: [Utah-astronomy] Re: Starpartyetiquetteforcrumbcrunchersandparents This is why in MY Dobson kit, right there next to the eyepieces and extinguisher, you will usually find a package of A&R hot dogs. I figure if my scope goes up, it won't be a total loss. ;) After this discussion, I am going to Kirkhams to have shoulder straps made for my 12" Dob, so I can carry it with me when I go hiking in the hills. Never know when I might get lost and need to start a fire. I know I can always find something to kill and eat, and while I am sitting around the smoldering scope, roasting prairie dogs and pot guts, I can always signal search aircraft with what's left of the mirror... ;)
The Clear Sky Alarm Clock said that we would have clear skies over SPOC starting at 20:00 hrs. That is 8:00 PM for those of us who pronounce VEGA like the car, and not VEEEEGA like Patrick. ;) There was a huge glowing nebula over Tooele which blocked our view of the rich star field regions of Sagittarius. There were intermittent drifting cloud formations straight overhead as well. This left us that portion of sky just above the duck pond to the west, and the area north in the direction of the SL International Airport to locate objects of interest that would keep those who cared to attend, interested. You know, if you stare at Mizar long enough, you could go crazy. The evening progressed, as did the openings through the clouds, and the sounds of: "Oh look, there's... never mind it's gone!" and, "where's M-13??? It was there a second ago..." could be heard up and down the line. About 9:30 PM folks started putting on their dew shields, but by the sounds of the geese overhead, I don't think that was dew that was falling. ;) I walked over to look through Rob's telescope. He had just placed a 2X Barlow under his eyepiece and as I peered through the scope, there staring back at me was NGC 36D, or, the "Great Hooter Nebula". I've heard stories about this Nebula. And how lonely Astronomers high atop mountains, have occasionally stumbled on this object while observing through sleepy and blurry eyes. This was indeed the wildest object I had ever seen. I wanted a better view, so I focused the image a little, and as I turned the focus knob, the Great Hooter Nebula faded before my eyes, and there in it's place was Epsilon Lyra. Doh! ;) Well, that's all I had. Oh yeah. The moon showed up just in time to provide enough light so we could see to pack our gear. ;) Now I'm done. Guy
participants (4)
-
Debbie -
diveboss＠xmission.com -
John and Lisa Zeigler -
Josephine Grahn