April 2009 - 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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Rewrite of Astronomy Day blog
by Joe Bauman 30 Apr '09

30 Apr '09

Hi Friends, with advice from experts (Siegfried and Sky), I have rewritten my blog. Pls take a look at the new version: http://www.deseretnews.com/blogs/1,5322,10000034,00.html?bD=20090430 -- thanks, Joe

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Astronomy Day
by Joe Bauman 30 Apr '09

30 Apr '09

Hi all, Here's my latest blog, which is about Astronomy Day, including SLAS activities. Bst wishes, Joe http://www.deseretnews.com/blogs/1,5322,10000034,00.html?bD=20090430

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Natural Bridges
by Lowell Lyon 30 Apr '09

30 Apr '09

Robert: I like you live on this beautiful place called Earth. I prefer to see the glass as being half full and so I enjoyed what good skies there were while I was there. I agree that April is an iffy month for the weather. I wish that the beautiful skies of Sunday through Wednesday could have continued. I'll bet they were great nights at Natural Bridges as well. Thursday night was beautiful and clear and calm. My goal was to see Omega Centauri which I did. I got a late start Thursday, so I observed from an area about 10 miles west of Blanding. Friday looked bad so I stayed in Blanding. Saturday night I got to the park after 11:00pm to see what things were like. What I wanted to see wasn't going to be rising until after then anyway. It became mostly clear and spectacularly dark not long after I got there and I didn't find the breeze objectionable. I didn't stay too long yet enjoyed the experience. Yes, it was cool yet nothing I couldn't deal with as I've been to Rush Valley with temperatures in the teens. In the future, I would probably suggest Capitol Reef or Bryce as they are certainly very dark on a good night and the motels are much closer to the observing areas. Capitol Reef is scheduled for dark sky observing in May, September and October and Bryce Canyon as you probably already know is in June. July and August new moon weekends will be at Wolf Creek. We'll have plenty of opportunities this year to get out. Lowell

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Sky Fog
by jim Gibson 29 Apr '09

29 Apr '09

I retried my Sky Fog test using an Astronomik EOS Clip-on CLS light pollution filter. This is what I found. Lower limit = 20 seconds: http://www.slas.us/gallery2/main.php?g2_itemId=1829&g2_imageViewsIndex=1 Near upper limit = 300 seconds: http://www.slas.us/gallery2/main.php?g2_itemId=1823&g2_imageViewsIndex=1 Aaaah…much better. My backyard location is in light pollution red and a 45 minute drive west will get me in the gray as seen from this map: http://www.slas.us/gallery2/main.php?g2_itemId=871&g2_imageViewsIndex=1 and the Pit-n-pole location looks like this: http://www.slas.us/gallery2/main.php?g2_itemId=1811&g2_imageViewsIndex=1 http://www.slas.us/gallery2/main.php?g2_itemId=1820&g2_imageViewsIndex=1 As you can see just another short 45 min from the Pin-n-pole location would put me in really dark skies. It is just over those mountains behind the telescope. I went to the Pit-n-pole location and at the end of the night I repeated the test. At that point I was in a hurry to leave and forgot to check my ISO and I ran the test at ISO 400 so the results are invalid. I was really excited when I took a 600 second shot with no filter second and the histogram was less than half way. When I got home I discovered I had the wrong ISO setting :>( I took another 90 second shot in the backyard without the filter and got slightly better results than I got a few weeks ago. I thought it would be worse because just 12 hours earlier it was windier than all got-out and when the sun went down the sky was dirty. I took the shot about 5am the next morning. I will have to take several shots on different nights to sort of get an average. I should have checked Daniel’s humidity chart but I forgot. Jim From: daniel turner <outwest112(a)yahoo.com> Subject: Re: [Utah-astronomy] Sky Fog Test with Canon Rebel XT To: "Utah Astronomy" <utah-astronomy(a)mailman.xmission.com> Date: Sunday, April 19, 2009, 4:40 PM Jim: Sky fog reading will vary from day to day and even hour to hour. What's happening is the ground lighting is reflected of of particles in the air. Last night's cirrus clouds out at SPOC are a good example. I rated the night as poor to fair because of the weather conditions. To get an idea about what conditions will be like before I go out, I look at the weather sounding map. http://weather.uwyo.edu/upperair/sounding.html First I look at the "Precipitable water [mm] for entire sounding" and when it's less than a half an inch the night will be good. If it's a half to a full inch, I may as well stay home. This will effect even the best of dark sites as well as suburban viewing. Next I look at the sounding data looking for layers of the atmosphere where the relative humidity is above 50%. These layers will map the cirrus clouding like those that occured last night. You would think that 50% would be alright but I think what is happening is that dust and pollen are hygroscopic and are starting the formation of water droplets even at just 50% humidity. April is bad because there is a lot of water on the ground that needs to be dried out and carried away by the atmosphere before we get good transparency. September is the best time of year for the same reason. Clear Skies DT --- On Sun, 4/19/09, Jim Gibson <jimgibson00(a)yahoo.com<http://us.mc307.mail.yahoo.com/mc/compose?to=jimgibson00@yahoo.com>> wrote: > From: Jim Gibson <jimgibson00(a)yahoo.com<http://us.mc307.mail.yahoo.com/mc/compose?to=jimgibson00@yahoo.com> > > Subject: [Utah-astronomy] Sky Fog Test with Canon Rebel XT > To: "Utah Astronomy" <utah-astronomy(a)mailman.xmission.com<http://us.mc307.mail.yahoo.com/mc/compose?to=utah-astronomy@mailman.xmissio…> > > Date: Sunday, April 19, 2009, 8:18 AM > > I found this article on measuring sky fog with a camera > quite interesting: http://www.pbase.com/samirkharusi/image/37608572. The > idea is to tell photographers a couple of things. One is to > give photographers an idea how their backyard skies compare > to a more preferred location. Of course they would have to > conduct the same test at the preferred location, and the > other thing it would tell them is how long they can take an > exposure before running into sky fog problems. As Samir > says, as long as the histogram is not attached to the left > side and it is also half way or less then you are sky fog > limited. > > I decided to give it a try for just those reasons. I was > not really sure I could judge the visual magnitude of the > sky in my back yard in Orem very well. I see many of you > can figure the visual magnitude without much trouble, so I > thought I better do something to learn how. In the past I > would look for Polaris and see how many stars I could see in > the little dipper. Usually, all I could see was Polaris, but > those skies are in or near the Salt Lake glow for me. > Anyway, I would figure my skies to be between vMag 2.0 and > 3.0 with average clear sky conditions. > > In following Samir Kharusi directions, only using a tripod, > I pointed my Canon Rebel XT with a Sigma 2.8 24mm-70mm lens > (set at 24mm) straight up and it didn’t take long to get > the disappointing news. I was reeeally hoping to get at > least 180 seconds or better of exposure time, but no dice. > http://www.slas.us/gallery2/main.php?g2_itemId=1790 . > In this image you will see that my histogram is slightly > past half way after 90 seconds. According to Samir’s > chart: > (This is probably not going to come out lined up.) > > Sec----------------1680---1062---660---420---264--168---108---66----42----27-----16.8 > Mins-----------------28---17.7----11----7.0----4.4---2.8----1.8---1.1----0.7---0.45---0.28 > > Mag/sq > arc-sec-------22---21.5----21----20.5---20----19.5---19----18.5---18----17.5---17 > > VLMag---------------8+?---7+?----7+?----6.6----6.1---5.6----5.1---4.6----4.1---3.6----3.1 > > that would put my visual magnitude between 4.6 and 5.1. > Uh…I don’t think so. I went back and re-read Samir’s > article and found this: > VISUAL LIMITING MAGNITUDES: For > convenience we may talk of Visual Limiting Magnitudes. Note, > for convenience only. The VLimMag translation scale shown > above is not absolute. It is observer dependent and very > subjective< > But none the less, The process is a non-subjective record > that I can repeat over time and in various locations and > hopefully I can learn something from it. Maybe by empirical > data I can match it to a visual scale for comparison use > only. (Any comments or insights would be helpful) > > In case you were wondering how I got the histogram image I > used Canon’s Digital Photo Professional. Samir says to use > the back-of-camera histogram; Digital Photo Professional’s > histogram looks just the same. However, it does look a > little different in PhotoShop. > > You may have noticed that the f/stop is set at 5.6 instead > of f/4. I had set the internal f/stop to 4 as suggested by > Samir, but when I switched to bulb then I got the f/5.6. I > am going to try and get out to the pit-n-pole in the next > few days and see what I get out there running exactly the > same test. > > I think I will also try this with the camera attached to > them 100mm ED and see what the difference is. Once I decide > on a procedure then I will have to stick with it for > comparison reasons. > > Results may vary, so each photographer will have to figure > their own sky fog limit. > > I have left out a lot of good stuff, like the minimum > exposure time and comments about signal to noise ratio so > be sure to read the article. My minimum exposure was about > 10 seconds when the sky fog histogram mountain separated > from the left side of the histogram frame :>(. That is > way too short for any kind of good detail. Therefore, I feel > that my sky fog limit is a very narrow band from my backyard > location. > > Any comments or suggestions are welcome. > > > Jim

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DISH Earth
by Patrick Wiggins 28 Apr '09

28 Apr '09

DISH Network subscribers might want to tune to channel 212. Called "DISH Earth" the channel is a live 24/7 picture of Earth from a camera on their EchoStar 11 geosynchronous satellite. http://www.dbstalk.com/showthread.php?t=156814 patrick

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Re: [Utah-astronomy] OT: Obama speech to the Nat'l Academy of Sciences re: science goals and spending
by Howard Jackman 28 Apr '09

28 Apr '09

P.S. - This post is intended to provide background information on changes in U.S. policy and is not intended to stimulate a general political discussion split along conservative/liberal lines. LOL!! Good luck with that! Howard --- On Tue, 4/28/09, Canopus56 <canopus56(a)yahoo.com> wrote: From: Canopus56 <canopus56(a)yahoo.com> Subject: [Utah-astronomy] OT: Obama speech to the Nat'l Academy of Sciences re: science goals and spending To: "Utah Astronomy List Serv" <utah-astronomy(a)mailman.xmission.com> Date: Tuesday, April 28, 2009, 6:21 PM A tiny url to the National Academy speech website http://tinyurl.com/djrc9b ------------ President Obama Addresses The National Academy of Sciences President Obama addressed members of the National Academy of Sciences on April 27, announcing a renewed commitment to science, technology, engineering, and medicine. Topics included America's energy future, revitalizing our health care system, science and math education, and allocating funding and implementing policies to ensure that America reclaims a position of world leadership in scientific innovation. ------------ Includes either video or audio only links. In the speech, Obama mentions the holding of science fairs and activities targeting young people to take up science, math and engineering careers. (Guess that makes this post marginally on topic.) Obama sets the objective of doubling increasing basic science and applied research spending to 3.0% of GDP. Space is mentioned obliquely and ends with the Apollo 8 "rising earth" photo as a metaphor for the contributions of science to nation. Discusses the role of the Apollo program in leading to improved consumer goods. "We will have to duplicate that," said Obama in creating a renewable energy future. Obama is the third president to address the Academy since its creation by Abraham Lincoln. Clear Skies - Kurt P.S. - This post is intended to provide background information on changes in U.S. policy and is not intended to stimulate a general political discussion split along conservative/liberal lines. _______________________________________________ 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.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com

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OT: Obama speech to the Nat'l Academy of Sciences re: science goals and spending
by Canopus56 28 Apr '09

28 Apr '09

A tiny url to the National Academy speech website http://tinyurl.com/djrc9b ------------ President Obama Addresses The National Academy of Sciences President Obama addressed members of the National Academy of Sciences on April 27, announcing a renewed commitment to science, technology, engineering, and medicine. Topics included America's energy future, revitalizing our health care system, science and math education, and allocating funding and implementing policies to ensure that America reclaims a position of world leadership in scientific innovation. ------------ Includes either video or audio only links. In the speech, Obama mentions the holding of science fairs and activities targeting young people to take up science, math and engineering careers. (Guess that makes this post marginally on topic.) Obama sets the objective of doubling increasing basic science and applied research spending to 3.0% of GDP. Space is mentioned obliquely and ends with the Apollo 8 "rising earth" photo as a metaphor for the contributions of science to nation. Discusses the role of the Apollo program in leading to improved consumer goods. "We will have to duplicate that," said Obama in creating a renewable energy future. Obama is the third president to address the Academy since its creation by Abraham Lincoln. Clear Skies - Kurt P.S. - This post is intended to provide background information on changes in U.S. policy and is not intended to stimulate a general political discussion split along conservative/liberal lines.

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Natural Bridges
by Lowell Lyon 28 Apr '09

28 Apr '09

To answer Erik: We went to Hovenweep National Monument on Friday to explore the Indian ruins. They are pretty amazing. We were close to the Four Corners, yet didn't sleuth out the "real" spot. Oh well. To answer Ann: Yes, I did see Omega Centauri in my 6" Meade refractor. I appears to be about three times the width of M13. Very impressive!! If any of you can head south in the next couple of weeks to see it, I would certainly give it a try. Lowell

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Natural Bridges
by Lowell Lyon 28 Apr '09

28 Apr '09

Hello: My wife and I left to go down to Natural Bridges on Thursday. Thursday and Saturday nights were both very clear and calm. The darkness and transparency are as good as I have seen anywhere in Utah. Saturday was the better of the two nights as the storm front that moved through earlier on Saturday really scrubbed the air clean. It is sad there weren't more people there as the sky was quite breathtaking. Hopefully some of you will come to Capitol Reef over Memorial Day weekend. Thank you. Lowell

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