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

Comet 17P obs rep
by Kurt Fisher 12 Nov '07

12 Nov '07

I set the alarm for 4:00am last night (11/12/2007) and spent a view minutes watching 17P from the Aves through a 15mm Christmas refractor. No images taken. Between storm fronts, the air was free of extinction and clouds. Light pollution was much less than usual. 17P is morphing from its jellyfish shape into the "trilobyte" shape seen in EE Barnard's Plate 105. http://www.skepticus.com/images/Holmes%20Plate105s.jpg >From the light polluted city, an averted image distortion can be seen around the coma, which I interpreted as the outer gas halo - the green fringe in the New Mexico image that Debbie posted about. http://www.zianet.com/rrichins/HolmesBig.htm No visual sign of the ion tail seen in high contrast images. At 4:30am, Venus rose over the Wastach and is extraordinarily brillant. Almost hurts to look at it _:) - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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Re: [Utah-astronomy] Color question
by Kurt Fisher 12 Nov '07

12 Nov '07

Patrick - I think the topic you are looking for is G2V Calibration (color balancing). G2V calibration is a technique that uses your filter set and images of class G2V stars to compute standard color correction calculators for your camera and filter sets. Chapter 20 in AIP4WIN contains discussion of the process and AIP4WIN has G2V color balancing tool. (Color | Color calculator). I haven't used it yet. For Maxim DL users, DL also has a G2V Calibration tool. It is demonstrated at this webpage: http://www.mistisoftware.com/astronomy/Process_m8.htm There is also a DVD specifically for Maxim DL and Photoshop illustrating how to use the DL color calibration tool. http://www.caelumobservatory.com/video/dvd2.shtml The calculators also account for extinction based on the altitude of the object at the time of imaging. Extinction effects each color wavelength differently. Berry's book (at 533) states for most CCDs and filters, the balance weights are 1:00.93:0.78. Happy imaging - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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Re: Utah-astronomy] Color question
by Kurt Fisher 12 Nov '07

12 Nov '07

Patrick asked: > Anyone here happen to know if there's a rule of thumb > about exposures for tri-color imaging? RGB Weights http://astrodon.com/oldsite/ColorExposure.html Goldman's RGB weight calculator http://astrodon.com/oldsite/RGBWeightCalculator.html http://www.astrodon.com/products/product.cfm?CatID=6 - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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RE: [Utah-astronomy] Comet 17P - EE Barnard images from 1892 outburst
by Kurt Fisher 12 Nov '07

12 Nov '07

Tyler, Glad you enjoyed it. Barnard always had such an unerring sense of artistic composition - seen again in his 102 plate of 17P. - Kurt http://www.skepticus.com/images/Holmes%20Plate102s.jpg _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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Re: [Utah-astronomy] recent comet photo
by Debbie 12 Nov '07

12 Nov '07

The Clear Sky Clock has changed to blue skies. Looks like I'll be taping Monday night football and setting up tonight. Weather is wonderful today! Debbie On Mon Nov 12 11:02 , Joe Bauman <bau(a)desnews.com> sent: >Go for it Deb! This is a comet every astrophotographer should try >for, because it's like nothing we've ever seen before and we'll >probably never see anything like it again. That is, we won't unless >we live another 105 years. -- 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://gallery.utahastronomy.com >Visit the Wiki: http://www.utahastronomy.com

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Color question
by Patrick Wiggins 12 Nov '07

12 Nov '07

Anyone here happen to know if there's a rule of thumb about exposures for tri-color imaging? That's to say, if an acceptable exposure for, say, Comet Holmes with the clear (luminance?) filter is 10" what would be the exposure times with the R, G and B filters? patrick

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Comet 17P - EE Barnard images from 1892 outburst
by Kurt Fisher 12 Nov '07

12 Nov '07

Per a Cloudnight's post, four plates taken by EE Barnard from the 1892 outburst have been scanned and posted to web. I have linked the urls into the Utah Astro wiki at: http://www.utahastronomy.com/Current_observing_events#From_the_web - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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recent comet photo
by Debbie 12 Nov '07

12 Nov '07

Hi, I found this on the digital-astro group this morning. It looks like the comet is losing it's tail. http://www.zianet.com/rrichins/HolmesBig.htm Thinking of trying some imaging Tues night on my driveway if not too windy. My scopes have way to much dust on them. Got a great view through the 15 X 70 binos Wed and Saturday nights. It's near the Perseus cluster. Will make a great wide- field picture. Debbie

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RE: [Utah-astronomy] Video capture?
by Kurt Fisher 12 Nov '07

12 Nov '07

P.S. - Maybe some of the experienced imagers here would have some comments about the high-end video cameras shown in the S&T classifieds - e.g. the Astrovid StellaCam3. The StellaCam3 has is cooled and has a direct video feed port that does not require a laptop. Such cameras are beyond my pocketbook, so I have no experience with them. - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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Finding faint asteroids
by Jerry Foote 11 Nov '07

11 Nov '07

For those interested in looking for faint new asteroids you might look into Astrometrica http://www.astrometrica.at/ This software is an astrometry program that allows stacking images along a suspected asteroid track such that the faint asteroid stacks positively while noise, etc. don't reinforce themselves. A neighbor of mine routinely tracks and finds asteroids in the 20-21 magnitude with a 14" C11. He takes 60, 1 minute images and then breaks them up into three groups of 20. Stacking each group to form three composite images he then blinks them. Thus there is a time separation of 20 minutes between each stack. As I am not an asteroid guy I don't have all of the operational details. The web site above does give helpful information and the software is free. Jerry Foote ScopeCraft, Inc. 4175 E. Red Cliffs Dr. Kanab, UT 84741 435-644-3167 jfoote(a)scopecraft.com

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