April 2007 - Utah-Astronomy - mailman.xmission.com

M57 +73PSW-3
by daniel turner 27 Mar '13

27 Mar '13

Mark your calendar for early evening May 7. Their will be a close encounter between the Ring nebula and periodic comet 73P. The comet will be close to earth so its exact position in the sky will depend stongly on your location on the globe. Go to spaceweather.com and use the link at the bottom of the page for "Observable Comets". 73p is in the list and includes orbital elements and a link for daily ephemerides. DT __________________________________________________ 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] Science Fair
by Michael Carnes 07 Jul '07

07 Jul '07

Don, you're cherry-picking your data. >I think there is still a controversy over how much economic development >contributes to global warming. While there is much yet to learn, the so-called controversy is largely clouding of the waters by those with an economic interest. Within the last month there's been renewed information of the rate of melting of the Greenland ice-sheet, in addition to melting in other zones, such as Mt. Kilimanjaro. Thousands of ice cores taken over the last century show that the ice goes back tens of thousands of years. If it had been as warm during the Roman era as your sources indicate, that ice would have melted then or would never have formed. Arctic permafrost that has been stable since the last ice age (as shown by the number of mammoths preserved in it) is rapidly turning to mush. Of course you can find a few scientists who disagree with this assessment, just like you can find a few scientists who don't like evolution. You can find a few scientists who believe in ghosts, in Sasquatch, in fairies, in alien abduction, and in all sorts of things. It is extremely rare in science that someone who goes against the grain is shown to be correct (Galileo, Kepler, etc). Most of them are just cranks.

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RE: [Utah-astronomy] Observing notes - Ealing 4-26-2007 Lunar visual
by Kurt Fisher 07 May '07

07 May '07

Don, Thank you for showing me a 2.5mm and 4m TMB Burgress planetary eyepieces on Saturn using Seigfried's new refractor at 400x-500x at Friday's Harmon's urban star party. A high-end engineered wide-angle 60deg short (3 and 5mm) eyepieces made good sense for planetary work. The wide-angle image spreads a dimmer image of the small planetary apparent disk over a relatively larger area of the fovea, resulting in a better perception of details. Spreading the planetary disk with a wide angle also probably breaks down the assumptions behind Knisely's useful magnfication rules-of-thumb that I normally apply to resolution limits. I'm not sure if we pushed Seigfreid's refractor into the range of extreme magnification on Saturn, but the review literature for the TMB mentions that unlike stock DSO lenses, it is engineered to reduce lateral scattering that causes multiple images of a feature to appear when used on very bright targets, e.g. - lunar visual observing. Those secondary scattered images are present in Plossels, but are two dim to perceived. Undoubtedly, your call that that in part was the distortion that I was seeing on the Ealing is right. Performance and price usually, or at least should be, related. At $100 a pop, the TMBs seem like a good price point compromise as compared to a TeleVue 2.5 or 5 Nagler at $290 a lens. You mentioned you were looking at the Plato craterlets as a resolution test. Here's Knisely's map for a Plato crater diameter sequence diagram: http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/520616/pag… Cloudy Nights, Lunar Forum, 7/18/2005 "Guide to Plato Craterlets" D. Knisely (map and list) - Kurt Astromart TMB eyepiece review http://www.astromart.com/articles/article.asp?article_id=464 Knisely's Useful Magnifications Modified to add a 5mm exit pupil for "low-medium power" LOW POWER (3.7 to 9.9x per inch of aperture)(6.9mm to 2.6mm exit pupil) LOW-MEDIUM POWER (5.1 to 9.9x per inch of aperture)(5mm to 2.6mm exit pupil) MEDIUM POWER (10x to 17.9x per inch of aperture)(2.5mm to 1.4mm exit pupil) HIGH POWER (18x to 29.9x per inch of aperture)(1.4mm to 0.8mm exit pupil) VERY HIGH POWER (30x to 41.9x per inch of aperture)(0.8mm to 0.6mm exit pupil) EXTREME POWER (42x to 75x per inch)(0.6mm to 0.3mm exit pupil) EMPTY MAGNIFICATION (100x per inch and above) Modified from D. Knisely, 5/14/2004 sci.astro.amateur Usenet post, Thread "Eyepiece advice, again" _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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RE: [Utah-astronomy] Portable power supply
by Kurt Fisher 30 Apr '07

30 Apr '07

Q. for expert electronic's lurkers: Is there way using a simple volt/ohm meter to determine the discharge state of the automotive battery that I use to power my scope? Currently, I roughly judge the state of discharge by looking at how many amps my battery recharger shows when it is first plugged in. Kim wrote: >> I had to go to MalWart tonight >> for my son and I happened to notice a 12V, >> 22Ahr battery/power supply there for >> about $60. . . . Anyway, do any of >> you have recommendations? I bought one of these portable automotive powertanks in the 20amp-hr range about two years ago and found them to not hold up in actual use. They are similar in amp-hour capacity to the 17amp-hr Celestron powertank. The main issues were: (1) cold weather, (2) steady voltage output and (3) heavy power draws when frequently slewing with a heavy mount. I am using a heavier Atlas (Synta) EQ-6 mount. 1) Cold-weather Cold weather can reduce battery capacity by 30%. So that 30amp-hrs with a lot of slewing on a heavy mount can quickly become 2 1/2 or 3 1/2 hours of steady 12 volts on a cold mountain ridge. 2) Good voltage regulation I understand that low-voltages can damage the electronics in some mounts, so I got hyper vigilent about having a good regulated voltage. So, I went back to using a car battery - an 51R coded battery - the R meaning it is supposed to stand up to repeated recharging. This was small enough to fit in a standard plastic battery box while leaving room to store my power inverters in same box. A cigarette lighter spilter gives me the same three ports usually included on the front of a commercial powertank. To adjust the low and varying voltage problem - and frankly not understanding electronics well - I bought a 120 volt inverter and then a Radio Shack regulated 120v to 12volt regulator converter. This was all on the theory that this would keep the dc output voltage steady at 12 volts as the battery's charge drained. Plus, that setup gives me both 12vdc and 120v ac at the scope as needed. Running the EQ-6 for 4 hours straight last Saturday with little slewing only drew the battery down by less than 1/4 (based on the 1.5 to 2 amp draw rate seen when charger was plugged in). 3) The amps that your mount draws Finally, the amount your mount draws is part of the equation of what battery setup is best. The Syntax EQ-6 draws, per the manual, 12vdc and 2 amps. A lighter mount will draw less power. Checking your manual for the load you are drawing for your various scopes is an idea. Joe Bauman wrote: >> The problem I've had is with keeping my >> computer and CCD setup going, which required >> AC. (I'll never be able to run a laptop >> for hours on batteries, I have concluded. I run my scope off the home-grown powertank setup described above. I run the laptop and camera off the laptop power - generally with a 2 to three hour reserve. Then I supplement the laptop power with an extension cord and cigarette lighter AC converter to my main car battery. This gives me about 4 to 4 1/2 hours without having to worry about a drained car battery in warm weather and closer to 3 hours in cold weather. Finally, I still have that portable automotive powertank in the 20amp-hr range that I bought about two years ago. It has a air hose and compressor built-in, so I use it as flat-tire insurance on long trips. For astronomy, I only use it a couple of times a year to power my Kendrick dew heaters - generally just running the heaters until the battery drains. - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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Testing the TEC 160 (Was Observing Notes - Ealing)
by Kurt Fisher 30 Apr '07

30 Apr '07

Don wrote, > Thanks for the link to the Plato image. It is a good > question how high the TEC 160 can go without getting > empty magnification. When you or Siegfreid get around to testing the TEC, I also have a spreadsheet that can produce a list of currently visible Argyle's high precision double stars for resolution testing. For an extended object test, here's another crater diameter sequence chart for Mare Serenitatis. http://www.lpod.org/?m=20060917 - Kurt Argyle, R. (ed). 2004. Tables 2.1-2.7, Test Stars for Binocular through 600mm Telescopes. In Observing and Measuring Visual Double Stars. Springer. _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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Portable power supply
by Kim 30 Apr '07

30 Apr '07

Hi all. I'm looking for a new portable 12V power supply, for use with either my Meade refractor or my 12.5" Cave-Astrola. I had to go to MalWart tonight for my son and I happened to notice a 12V, 22Ahr battery/power supply there for about $60. I didn't catch the manufacturer's name, and I am always hesitant to buy anything from that retailer. Anyway, do any of you have recommendations? I want at least a 15Ahr battery; a built-in inverter isn't necessary (I already have an inverter I could use). Any ideas would be welcome. Thanks, Kim

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Re: [Utah-astronomy] Portable power supply
by Wayne Sumner 29 Apr '07

29 Apr '07

I bought a 12 volt deep discharge 600 amp-hour battery at Sam's Club for $50 three years ago and it has been great! It's heavy, but I never have to worry about running out of power. Wayne A. Sumner Math/Physics/Astronomy/Engineering Boy's Tennis Coach Northridge High School Davis School District (801) 402-8610 >>> "Kim" <kimharch(a)cut.net> 04/27/07 11:09 PM >>> Hi all. I'm looking for a new portable 12V power supply, for use with either my Meade refractor or my 12.5" Cave-Astrola. I had to go to MalWart tonight for my son and I happened to notice a 12V, 22Ahr battery/power supply there for about $60. I didn't catch the manufacturer's name, and I am always hesitant to buy anything from that retailer. Anyway, do any of you have recommendations? I want at least a 15Ahr battery; a built-in inverter isn't necessary (I already have an inverter I could use). Any ideas would be welcome. Thanks, Kim _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.utahastronomy.com

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Obs Notes - DSI solar iamge taking - Sunspot 953
by Kurt Fisher 29 Apr '07

29 Apr '07

Spent from 1 to 4:30 pm MST 4/29/2007 observing solar active region 953 consisting of a large group of four sunspots with a light filament on one side. This is a nice region and I recommend it in either Ha or white light. The observing point was Copperton Park at 11th Ave and Virginia Street. About 5 small prominences were viewed in Ha on a PST mounted on an Orion Atlas EQ-5 mount. Prominences could still be seen after 3pm when the Sun is at a lower altitude - a unusual level of seeing. Unlike my experience with lunar tracking, solar tracking of the Atlas EQ-5 was dead-on - holding a center easily for about 10 minutes at a time. I also began some preliminary work with the DSI I mounted on this EQ-5 inorder to make solar images. I didn't get any useable images, but was able to locate the prime focal length and get the camera to prime focus. Lessons learned follow, if it is of any use to others here. The prime focal plane on a PST is 70mm above the top body metal. The PST works the best with a 20mm down to a 12mm eyepiece. A 9mm e.p. if screwed home will not reach prime focus. I didn't try backing a 9mm e.p. out of the holder to test achieving visual focus with shorter length e.p.'s. A 2x barlow gives the best visual experience. Higher magnifications could be had with a shorty 2x barlow (Orion) and a 20 or 15mm e.p. My 3x barlow would not yield a useable focal plane. I'll have to compute the AB distances between the barlow and the PST prime focal plane and try again. Measuring calibers are a useful tool to have when working with a PST and various eyepieces. After estimating the inset of the DSI CCD chip relative to the body, I used measuring calibers to position the DSI chip at the PST prime focus 70mm above the base. My imaging laptop was placed on a small table next to the scope. A carboard banker's box with suitable holes cut out for my hands and a small hole viewing the laptop screen was placed over the laptop. The viewing hole was cut across an edge of the box. A dark coat went over the box. On the front side, I taped a black plastic bag, laping the black plastic under the coat. This made the set up sufficient light tight so I could focus the scope on the laptop screen, adjust the tracking controller and run the laptop. Of course anyone walking by, legitimately found the whole scene amuzing and comical. I was working in monochrome mode which probably was a mistake. Getting a sharp focus still proved illusive in monochrome mode. Dust in the optics was a significant problem. I'll have to go back through the DSI and the PST optics to make sure everything is blown out. The Meade Autostar software would not properly estimate a color or black and white exposure. I had to manually drop the gain to 50 and the exposure to 0.007 seconds. Next time around, I'll probably work in color mode. I've had better results in color in the past. I probably will also try a Hartman mask (that I fabricated for my SLR camera) on the PST to see if the focusing process can be made to work faster. Finally, I'll expand to trying the DSI with the 2x barlow. I'm not sure how one would go about taking white flats with a PST. Any tips would be appreciated. - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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Re: [Utah-astronomy] Impromptu laser comparison at SPOC last night
by Chuck Hards 29 Apr '07

29 Apr '07

I'd heard the term "potato masher" used in WWI descriptions, but those grenades had a much larger cylinder on the end...it actually looked like it could mash spuds. This laser was much thinner. Bob said it took "C" size batteries, as opposed to the AAA that the pen-style lasers use. On 4/29/07, Joe Bauman <bau(a)desnews.com> wrote: > > I always thought it was a "potato masher" grenade .... But very nice > report, Chuck! -- Joe > > _______________________________________________ > Utah-Astronomy mailing list > Utah-Astronomy(a)mailman.xmission.com > http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy > Visit the Photo Gallery: http://www.utahastronomy.com >

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Impromptu laser comparison at SPOC last night
by Chuck Hards 29 Apr '07

29 Apr '07

A phone call from Patrick informed me that Bob was at SPOC with his 50mw laser, so even though I was beat from tilling and planting the back 40, I showered and drove on out. (Any excuse to drive the rotary speed machine!) I was surprised to find that Bob's laser is not a "pen" style pointer, but something more like a conventional flashlight in size (post the details, Bob). Patrck likened it to a WWII German "stick grenade". We had a small assortment on-hand; Boyd had his $35 Lucky Duck Special and I had my Computer Geeks laser as well as 20mw Lucky Duck and Beta pointer. I did not bring my light meter, as the 20mw units are close to the meter's upper-range limit as it is. As expected, the 50mw was noticeably brighter than either the Lucky Duck 20mw or the Beta pointer- but not as much as you'd think. After careful consideration, I would estimate about a 30%-50% increase in brightness. I don't think I could be convinced that it was twice as bright, to the eye. But this is a very subjective, individual perception. The $80 Lucky Duck 20mw was easily, handily visible even under the waxing gibbous moon, as was the $120 Beta laser. They are just as useful even under twilight or suburban skies as the 50mw. In the moonlight, the $35 Lucky Duck and the Computer Geeks lasers were almost invisible. You had to be standing very close to see the beams of both. They don't stand-up to bright moonlight. I hope to get a metered reading on the 50mw one day, when I have a suitable filter to bring it's brightness within range of the meter. Re-measuring the Beta and Lucky Ducks with the same filter will tell us how much brighter the 50mw actually is. The verdict? Based on what I saw, the 50mw is the brightest and if cost is no object, it's definitely the brightest sky pointer. The Beta is still the brightest of the pen-sized pointers and not too far behind the 50mw unit. But I also cannot see spending $400 (is that right, Bob?) on an only slightly brighter laser. Taking convenient size, visibility AND ecconomy into account, the clear winners are the 20mw Lucky Duck and Beta pointers. Almost as bright, 1/5 the size and 1/4 the cost, and no permit needed. If Luck Duck still has the 20mw units available, that would get my recommendation for the prospective laser purchaser. Your mileage may vary- if you need the absolute brightest pointer you can get then maybe the "rock show" laser really will fill the bill.

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