September 2005 - Utah-Astronomy - mailman.xmission.com

X6.5 solar flare
by astrodeb＠charter.net 09 Sep '05

09 Sep '05

Here is an image of today's solar flare. http://gallery.gmayfield.com/sun/flare_lg9905 Debbie

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Re: German Equatorial -revisited-
by Chuck Hards 09 Sep '05

09 Sep '05

Further considerations - And BTW I just finished my daily run and my head is MUCH clearer. 3.16 miles in 33 minutes- not bad for an old man, eh? ;) The equatorial platform in many of it's forms never has a true declination axis, and often has only a virtual polar axis- yet is is obviously firmly in the equatorial class of mounts. In truth it's just a split-ring, with the entire upper portion of the ring sliced-off. Whether the drive train uses conic segments, concentric ring segments, or inclined planes, kinematically they are all in the same family. Again, we see that the name is derived from the motion the mount imparts, not the presence and alignment of a secondary axis. In this case, as with the universal pivot atop the polar axis, there is no secondary axis. Declination motion is achieved in some cases by use of the altitude axis of an alt-az mount atop the platform. That motion is not true declination except when the object is on the meridian. In fact when the object is on either horizon, the altitude axis becomes a pseudo-polar axis, and the azimuth pivot becomes the declination axis! The "barn-door" mount is also an equatorial mount and can be considered a variation of the equatorial table with a true, hard polar axis. Range of motion in declination can be achieved by the methods discussed above. I am also reminded of the sphere mount as executed by James Gagin, I believe it was, about 25 or 30 years ago. Again there was no true declination axis- the telescope was essentially a huge "Astroscan" in shape, floating in a water bath. Once slewed to its target, a vacuum-pump connected suction cup, motor-driven and aligned with the NCP, engaged the sphere and began to drive the telescope in RA. Another example of a true equatorial mount with no mechanical secondary axis at all. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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Re: German Equatorial
by Chuck Hards 09 Sep '05

09 Sep '05

Actually, while strictly true that the "second" axis is parallel to the (celestial projection of) earth's equator, it does intersect it directly-so is more accurately called coincident with- parallel is not quite the best term. The secondary axis never changes latitude (declination). The telescope is attached to, and free to rotate about, that secondary axis, describing north-south motion- the ability to point at any declination. The equatorial motion is strictly a function of the polar, or primary axis. You can have an equatorial mount without any secondary axis at all. Declination can be changed by using a universal pivot joint- a ball and socket, for example. The mounts name is more accurately descriptive of the motion it imparts, rather than where one particular axis is pointing. Alt-Az as a descriptive name works for the same reason. And of course the English Yoke is also known as an equatorial, for the same reason. As is the equatorial fork. I was trying to be funny, I'll know better next time. The "where the second axis is pointing" definition is inadequate and not truly descriptive of, or universally applicative to, the kinematics of all equatorial mounts. > From: Canopus56 <canopus56(a)yahoo.com> > The equatorial mount takes its name from the fact > that > while the first drive-powered axis is parallel to > the > Earth's axis, the second is parallel to Earth's > equator. The German Equatorial Mount (GEM) takes is > name from the historical development that you note. > English Yoke mount is also known as the equatorial > mount - for the same characteristic that its > secondary > axis is parallel to the Earth's equator. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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Re: Active region 808 rotating into view
by Chuck Hards 09 Sep '05

09 Sep '05

I don't get excited about any aurorae, unless I happen to see them happening- whether or not they are "in season". Did you see the one in particular that I mentioned? >From several years ago, the one Joe wrote about in the DesNews, that actually swamped-out the light pollution of the Salt Lake valley? > From: Canopus56 <canopus56(a)yahoo.com> > I generally don't get excited about low-latitude > aurora in September, since the low latitude aurora > season doesn't start until November or December. ______________________________________________________ Click here to donate to the Hurricane Katrina relief effort. http://store.yahoo.com/redcross-donate3/

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Re: Active region 808 rotating into view on Sun
by Chuck Hards 09 Sep '05

09 Sep '05

24 hours later and 808 is now fully visible on the solar disk- it is indeed a massive spot complex. There is also a smaller spot north of the main group. It would be nice to have an aurora like that huge one several years ago. My wife and I still talk about that night. Hopefully it wasn't a once in a lifetime display for this latitude. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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RE: [Utah-astronomy] cylindrical parabolic antenna [was: amateurradioastronomy ]
by Dale Hooper 09 Sep '05

09 Sep '05

Hi Kim, In our free body diagram we can't forget that the textbook also obeyed all the laws of physics. <g> The big old C band ( 10 GHz) dishes were setup to move along the celestial equator (dec 0 degrees) to pickup geostationary satellites. I suspect that the off axis noise (i.e. sidelobes and all that stuff) from the cylindrical parabaloid would give you more problems than a parabolic dish with a standard feedhorn and low-noise block (LNB). As far as the dinosaur dishes - that is what I am using. I took off the standard feed horn, LNB, etc. and replaced it with a feedhorn, low-noise amplifier (LNA), and very low loss coax that is usable at 1.4 GHz instead of 10 GHz. If you are interested, there are a couple of articles that I wrote for the OAS Star Diagonal a few years ago concerning my setup. Dr. Palen from Weber State has them archived at the following URLs: http://departments.weber.edu/physics/palen/OAS/Newsletter/Mar01.htm http://departments.weber.edu/physics/palen/OAS/Newsletter/Apr01.htm So, get that radio telescope project back out and get back to work on it - its a lot of fun! Clear skies, Dale. ________________________________ From: utah-astronomy-bounces+dale.hooper=sdl.usu.edu(a)mailman.xmission.com on behalf of Kim Hyatt Sent: Thu 9/8/2005 9:52 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] cylindrical parabolic antenna [was: amateurradioastronomy ] Dale: Yeah, I think that you're basically right on all points, but I'm relying on 35-year-old memories from my AP physics textbook, the one that went end-over-end down the median of I-15 with me and my '65 VW Beetle when we tried to defy Newton's 2nd Law of Motion one very cold December morning in 1971. Or was it the 1st Law? I've always been grateful to UDOT for modifying the design of the steel guardrails the previous summer so that I vaulted over the railing rather than getting impaled on it when our respective molecules collided. But I digress... In the days of the six- or seven-foot satellite TV dishes I wondered why it wouldn't work to build a cylindrical parabaloid (again, simplicity and cost) rather than pay the hundreds or thousands that the dish makers were charging. And, do those dishes, that I assume are now dinosaurs, have any use in amateur radio astronomy, or are they "tuned" (wrong terminology?) to the wrong wavelength? Do you, Dale, or does anyone else know the answers? I don't have enough hobbies and I've been thinking about building that aborted radio telescope that I never completed in high school. ;-) Maybe I'll even try to locate my old Beetle and restore it, too. The physics text could even still be inside. Who knows, I might even find that old stash of...never mind. Kim

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German Equatorial
by Chuck Hards 09 Sep '05

09 Sep '05

Bill, it was designed by telescope maker Joseph Fraunhoffer, for the Dorpat refractor, which my memory is telling me was a 9". Only one axis is aimed at the pole, the instrument mounted on it can be aimed anywhere. Objects being tracked by such a mount describe motion parallel to the celestial equator. Why is the English Yoke not called even equatorial? The nomenclature of mounts has no logic. William Biesele <bill(a)biesele.net> wrote: > Etymology question for the group. Why is this kind > of mount called a > german equatorial mount? I assume the first word is > from the country > in which it was invented or popularized. The third > word is obvious. > But why equatorial instead of polar? It's aimed at > the pole not the > equator. ______________________________________________________ Click here to donate to the Hurricane Katrina relief effort. http://store.yahoo.com/redcross-donate3/

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good times
by Kim Hyatt 08 Sep '05

08 Sep '05

With all the bad news we've been having lately, I thought I'd share a happy moment. I have a few reasons to feel good today. I was driving through Spanish Fork Canyon recently, sun shining on the deep red and orange maple leaves (looks like we'll be treated to a glorious, colorful fall this year), listening to my favorite oldies-but-goodies R&R station, when I heard the following lyrics that some of you may also recognize: Things are goin' great and they're only gettin' better. I'm doin' all right and gettin' good grades. The future's so bright - I gotta wear shades. I've been waiting a long time for a better future for me and my family, and I think I may finally need shades. I don't mean to belittle at all what people are going through elsewhere, but we can all still have/see a little hope - the proverbial silver lining - in a few places. I hope I can share what I've been given with those who may need some help. And that also goes to any of my good friends closer to home. So, even if y'all just need to get away from the koyaanisqatsi of the Wasatch Front, come rest yer bones in Sanpete and visit us in Mt. Pleasant. Skies are dark here...at least when the weather cooperates. Kim

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RE: [Utah-astronomy] cylindrical parabolic antenna [was: amateur radio astronomy ]
by Dale Hooper 08 Sep '05

08 Sep '05

Hi Kim, I was thinking a bit more about the cylindrical parabaloid and a few synapses finally started to fire... I believe at the focus of the parabola you have basically a single dipole antenna? My understanding is that the dipole needs to be an odd number of half-wavelengths in size. This would basically be a hybrid and I think would have some of the advantages/disadvantages of the other types. Advantages: Aperture - as you mentioned you could build a good sized antenna using some plywood and mesh or screen Price - Very cheap to build and you could use scraps from other projects Disadvantages: Noise rejection - Since your feed is a single dipole I think you would get a lot of off axis noise. Bulkiness - It would probably get fairly heavy if the length was much more than a meter. I remember now that back in high school there was a kid at the regional science fair (at Weber State) that built a cylindrical parabolic radio telescope. (He probably stole your idea since this was 1977 <g>). He covered the parabolic surface with aluminum foil. He said it worked pretty well but I didn't know enough to ask any good questions. As I recall it was obviously movable but was probably more semi-portable. Clear skies, Dale. > ...snip... >I finally determined to build a Yagi > array, but not before I realized that a cylindrical parabaloid would have > also been very easy to build and with very little skill or exotic > materials > required. I don't recall why I settled on the Yagi array, I have simply > forgotten too much of the physics involved. And that finally brings me to > a > question I have for you and others: What would be the > advantages/disadvantages of one type of antenna over another? I would > still > rule out the conventional parabolic dish because of the relative > complexity > of its construction for a basement tinkerer like me. However, the > cylindrical parabaloid is still quite easy to construct with some plywood, > a > simple plot of a parabola on a piece of paper for a pattern, and some > hardware fabric or insect screen to cover the surface. Can anyone > enlighten > me? Remember, you need to explain in terms my few remaining viable brain > cells can comprehend. > > Thanks all.

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RE: [Utah-astronomy] Sept. QST source for RT upgrade help
by Dale Hooper 08 Sep '05

08 Sep '05

Hi Gary, It's always great to hear from you! Chris suggested checking the library and I found out that the USU research library has it (the rest of the library system up here is a joke). I found some info about a new AlfaSPID az/el rotator that might do the trick. I hope you'll be able to make it to the OAS meeting tonight so I run some info by you. Thanks again & clear skies, Dale. > -----Original Message----- > From: utah-astronomy-bounces+dale.hooper=sdl.usu.edu(a)mailman.xmission.com > [mailto:utah-astronomy- > bounces+dale.hooper=sdl.usu.edu(a)mailman.xmission.com] On Behalf Of Gary > Liptrot > Sent: Thursday, September 08, 2005 5:21 PM > To: Utah Astronomy > Subject: Re: [Utah-astronomy] Sept. QST source for RT upgrade help > > Hi Dale, > I have the September QST sitting right here. The article is a product > review called "A Look at a New Generation of Antenna Rotators." The > author > concentrates on MEDIUM duty rotators some of which I know have been around > for a while. They are single axis only but some can be computer > controlled > quite nicely. > They review the following rotators: > AlfaSpid > C.A.T.S. RD-1800 > Hy-Gain Ham-V > Prosistel PST-641D > Yaesu G-800DXA (I have the G-1000SDX on a 46 foot tower) > > I know that the special satellite tracking rotators (not mentioned in the > article) are two axis and computer controlled. I don't know what the > wind-loading specs are compared to the others in the article. Look up > Yaesu's satellite rotators to find out their specs. They would be the > best > if they will handle the weight. Even if you just get one axis I imagine > that you would have to build a small beefy mount with a couple of thrust > bearings around the pipe that runs to your dish. Not hard to do. What do > those 10 foot dishes weigh? I know with everyone turning to small > satellite > dishes the large black mesh dishes that were made for the analog C or the > Ku > bands are a dime a dozen. > > The wind loading for the six rotators in the article run from 10 to 25 > square feet. I have a huge yagi tri-bander that only runs 11 square feet > of > wind loading. It's boom is 24 feet long and four inches in diameter and > the > longest element is 28 feet. I did break the shear-pin in a 90mph canyon > wind but as long as only one axis of rotation is needed then I'm sure that > these rotators would work. > > I've seen the printouts from Dale's RT work and it's amazing. > > You mention noise rejection but spousal rejection is much more serious... > B) > > I can get you the QST article if you need it Dale, you've got my home > email. > > 73 de n7zi > Gary > > "Why buy something for ten bucks when you can make it for a hundred." JR >

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