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

Re: [Utah-astronomy] How red is Mars, anyway?
by cmh856＠aol.com 28 Mar '07

28 Mar '07

Joe, a low sun angle means increased reddening from atmospheric extinction- look at the shadows in the painting. An astronaut on Mars wouldn't see the same shades and intensities at all times- just as you don't here on earth. A terrestrial example would be a very red sunset seen from an arctic location. Blue & white everywhere, but it all turns deeply red at sundown (or sunup!). Dust & other suspended particulates are the culprits. So, the answers to your questions are: No, and probably not, although I'm sure there is a lot of color processing and contrast stretching of rover images. In a message dated 3/28/2007 2:05:51 PM Mountain Standard Time, bau(a)desnews.com writes: Hi all, check out this NASA rendering of humans on Mars. Then remember the views Spirit and Opportunity have been sending back. My question: is this NASA artist stuck in some 1950s fantasy about Mars or are we getting paled-out views from the rovers? Thanks, Joe http://science.nasa.gov/headlines/y2007/28mar_firststeps.htm?list173374 _______________________________________________ ************************************** See what's free at http://www.aol.com.

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Phoenix Mars mission EDL animation
by Patrick Wiggins 28 Mar '07

28 Mar '07

A animated overview of the entry, descent and landing phase of the next (set to launch in August) US mission to Mars. http://phoenix.lpl.arizona.edu/video/phoenix_landing_low.mov (~8 MB) http://phoenix.lpl.arizona.edu/video/phoenix_landing_high.mov (~36 MB) pw

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New location for SLAS meetings?
by Patrick Wiggins 28 Mar '07

28 Mar '07

http://www.sltrib.com/search/ci_5492353 :)

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Re: Laser Test
by cmh856＠aol.com 27 Mar '07

27 Mar '07

Not surprisingly, the red lasers all test at a mere fraction of the green lasers. All of mine are only a couple thousand lux at most, or less. Even my "construction" laser, used for projecting a straight line and various other uses in framing and masonry. All my red lasers are labeled "class II" (<1mw) and "class IIIa" (<5mw). At 630-680 Nm, the meter's sensitivity is only about 1/4th to 1/5th what it is at 532 Nm (per the response diagram included with the meter), so that has to be taken into account as well. It appears to have been designed to approximate the range and spectral response of human vision (makes sense). As of now, I plan on being at SPOC on Friday night for a refresher course on the 16" Cassegrain. I will bring my light meter and lasers; if anyone cares to come on out with their laser(s), we can quickly check output in terms of lux. ************************************** AOL now offers free email to everyone. Find out more about what's free from AOL at http://www.aol.com.

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For those who's friends think astronomy is odd
by Patrick Wiggins 27 Mar '07

27 Mar '07

Chuck (and others), The next time a spouse, neighbor or friend tells you they think the creations of ATMs are weird just tell them what some non-astronomer locals are building to prepare for the upcoming "mini-Burning Man" at Seabase. pw :) p.s. Hey, Chuck, do you think they could maybe include a few lasers...? > The Amazing Jellyfish From The > Year 12,000. The concept: a 1950's sci-fi B movie vision of a highly > evolved, intelligent, part-robot, oversized jellyfish from the > future. Last year it manifested at Black Rock as a stationary EL- > wire dome; this year it will make the journey into our time and > dimension in a vehicular form, with seating for twelve on the lower > level, and up to six on the upper level, inside the inner dome of > the body of the jellyfish. The structure is built of welded steel on > the stripped chassis of a huge van, and when complete it will be 15 > feet tall with an outer dome 16 feet in diameter. Jared is working > with a team of electrical engineers with backgrounds in cognitive > neuroscience, 3D graphics, and genetic algorithms to develop a > custom lighting system comprising 4700 LEDs to wrap the inner dome > with animation patterns and – possibly – interactivity with its > riders. If you're interested in participating in assisting in the > manifestation of the jellymobile, and contributing your skills or > even just learning about metalworking, lighting, or upholstery in > the process, the jellycrew needs as much help as they can get.

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Re: Laser test
by cmh856＠aol.com 27 Mar '07

27 Mar '07

Due to a family illness, my scheduled time-off has been scuttled, and I will not be able to conduct the laser test next week, or for the forseeable future. Thanks to those who volunteered to participate, we'll do it sooner or later before the weather gets too hot. ************************************** AOL now offers free email to everyone. Find out more about what's free from AOL at http://www.aol.com.

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Re: Lucky Duck laser - hard numbers
by cmh856＠aol.com 26 Mar '07

26 Mar '07

My digital light meter arrived, so I have some preliminary numbers for the 3 different green laser pointers I own. This isn't the "big test" Wayne and I are planning, just a trial run with the meter and the lasers I have on-hand, to test the concept. The meter's sensitivity peaks at about 550 Nm, so it works well with green lasers, which emit at 532 Nm. For each laser, I held it centered and in contact with the diffusor lens of the photo-diode. Here are the results: ComputerGeeks.com laser: ~9,000 lux Lucky Duck "20mw" laser: ~32,800 lux Beta "optimised" 5mw laser: ~40,000 lux The readout on the meter would shift during testing by some tens of lux, thus the "approximate" symbol before each reading. Preliminary conclusions: Because I had trouble choosing between the Lucky Duck and Beta for brightest to the eye, it seems that differences of less than about 20% are not enough to discern visually, in side-by-side comparison. The ComputerGeeks.com laser was always obviously a lot dimmer than the other two, and is probably a true 5mw diode. It appears that Noah Acres' (of Lucky Duck) statement that my Beta laser was probably more powerful than the advertised 5mw is correct. Remember that my own Lucky Duck 20mw tested at just over 19mw according to Mr. Acres, so it would appear that the Beta laser is more powerful than 20mw, based on my test. I am not sure why Beta calls thier product an "optimized 5mw" laser, unless the careful wording is to help comply with government regulations. They would clearly generate more sales if they called a duck a duck (pun intended!). Wayne and I still want to perform further tests to include current draw under load, visual brightness comparisons, as well as test a larger sample of lasers. Some useful and interesting consumer data can be generated, and it will be fun as well. Please let us know if you want to participate, or just volunteer your laser if you can't make it for the test. I promise to take good care of any lasers loaned for the test and return all of them in the same condition that they were borrowed in. We are probably going to do some initial testing, just to verify the robustness of our procedures and apparati, on a weeknight next week, before the final testing on a weekend, hopefully at a star party. The more the merrier, and thanks to those who have volunteered so-far. I may try testing my red laser pointers later tonight, as time permits. I'll post the results if they are worth note. Again, I have to give Guy credit for being ahead of the curve on super-bright lasers. He's the one who recommended the Beta laser. ************************************** AOL now offers free email to everyone. Find out more about what's free from AOL at http://www.aol.com.

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Re: Lucky Duck laser
by cmh856＠aol.com 25 Mar '07

25 Mar '07

I spent about 40 minutes tonight with the Lucky Duck 20mw and my Beta laser, trying to convince myself that one was brighter than the other. At first they seemed identical in brightness, so I switched batteries and again they seemed really, really close. By the time I called it quits, however, I was fairly sure that the Ducky was actually just a bit brighter. I have an inexpensive digital light meter on the way so hopefully some numbers can be put to the output brightness. When two different lasers are so close to the same visibility, strictly comparative tests don't have quite the resolution to pick a clear winner. Wayne and I are still trying to pin-down a date for an outdoor, night-time testing session. If you want to include your laser, please let either one of us know that you are interested. Some who I have corresponded with already are favoring a weekend- either a Friday or Saturday night, but I'm good for most any night except Thursdays. Of course, most of us can stay up later on the weekend. I'd like to have data on as many lasers as can be rounded-up. Even different examples of the same model are most welcome. That would yield useful consistency data on particular models. At Chris's suggestion we plan to check current draw, as well. BTW, both are clearly much, much more easily seen (especially under a waxing moon and suburban light pollution) than my non-optimized 5mw unit from ComputerGeeks.com, although that one was under $45. ************************************** AOL now offers free email to everyone. Find out more about what's free from AOL at http://www.aol.com.

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Re: [Utah-astronomy] How not to install a mirror
by cmh856＠aol.com 22 Mar '07

22 Mar '07

A magnifying glass? How cute. As a kid, I used a Fresnel lens, 18" on a side. It would melt asphalt! Thank you, Edmund Scientific. But I have to admit that the guillotine is a nice touch... In a message dated 3/21/2007 3:26:15 PM Mountain Standard Time, kimharch(a)cut.net writes: Did anyone else fry ants with a magnifying glass as a kid? Or am I just warped? (OK, don't reply to that question - I already know the answer.) I bet no one else built a guillotine to execute offending grasshoppers... ************************************** AOL now offers free email to everyone. Find out more about what's free from AOL at http://www.aol.com.

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Re: [Utah-astronomy] Re: Lucky Duck laser
by cmh856＠aol.com 21 Mar '07

21 Mar '07

Industry standard, Michael, it will fit the test stand nicely. Hope you can come to the test, and bring your Duck. My week has been hectic but pretty good overall. My wife is almost used to me sitting in the new car in the garage late at night, making "vroom" noises and listening to the stereo (it's better than the indoor stereo). In a message dated 3/21/2007 6:42:15 PM Mountain Standard Time, MichaelCarnes(a)earthlink.net writes: > What's the O.D. of the 5mw Lucky Duck laser, Michael? Let me know > and I can determine if it fits the test stand. > Sorry to take so long getting back to you Chuck. It's been that kind of week. It's STILL that kind of week. O.D. is right on 1/2". Michael ************************************** AOL now offers free email to everyone. Find out more about what's free from AOL at http://www.aol.com.

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