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

Science and astronomy podcasts in iTunes
by Michael Carnes 30 Jun '05

30 Jun '05

The newest version of iTunes has added support for so-called podcasts. For those that don't know, a podcast is an audio file that can be downloaded and played back on a computer or an iPod. This audio format has been available for a while, but has required a fair amount of work on the part of the recipient. Apple has now built that all into iTunes so it's a lot easier to do. The iTunes programs runs on either PCs or Macs, so we can avoid computo-religious wars. In almost all cases, the podcasts are free. You "subscribe" to the podcast and your computer automatically receives new programs as they become available. The audio format is compressed, so those folks with modems might be able to receive them without too much bother. Anyway, I installed the new version last night and went looking around to see what I could find. It turns out there are quite a few astronomy shows and even more on general science topics. For example, the NPR show "Science Friday" is there. The audio quality is quite good. Sure beats talk radio--although you can get that too, if you need a certain daily dose of invective. So there it is. Pretty cool.

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Seeing the comet now at SPOC
by paw＠trilobyte.net 29 Jun '05

29 Jun '05

Bruce Grim, Mark Bloomenthal and myself have now all seen 9P/Temple 1 tonight from here at SPOC both with the Big Scope and (surprisingly) the ADA scope. That being the case, the chances are good that there will be a SPOC "Wallop Watch" Sunday night. However, that has not been confirmed. Look for official word in News. Patrick ___________________________________ NOCC, http://nocc.sourceforge.net

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Ken Harris commeents
by Boyd McNeil 29 Jun '05

29 Jun '05

Good for you Ken, your comments are long overdue regarding Patrick.The Society would miss his efforts were he not with us. Boyd utah-astronomy-request(a)mailman.xmission.com wrote: >Send Utah-Astronomy mailing list submissions to > utah-astronomy(a)mailman.xmission.com > >To subscribe or unsubscribe via the World Wide Web, visit > http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy >or, via email, send a message with subject or body 'help' to > utah-astronomy-request(a)mailman.xmission.com > >You can reach the person managing the list at > utah-astronomy-owner(a)mailman.xmission.com > >When replying, please edit your Subject line so it is more specific >than "Re: Contents of Utah-Astronomy digest..." > > >Today's Topics: > > 1. Re: nothing serious (Canopus56) > 2. Re: nothing serious (Rob Ratkowski) > 3. Re: Re: [Utah-astronomy] nothing serious (astrodeb(a)charter.net) > 4. Re: nothing serious (Rob Ratkowski) > 5. Re: nothing serious (Canopus56) > 6. Re: Re: [Utah-astronomy] nothing serious (Chuck Hards) > 7. Re: nothing serious (Rob Ratkowski) > 8. Re: Re: [Utah-astronomy] nothing serious (astrodeb(a)charter.net) > 9. Congratulations, Patrick!!! (Ken Harris) > > >---------------------------------------------------------------------- > >Message: 1 >Date: Wed, 29 Jun 2005 16:48:55 -0700 (PDT) >From: Canopus56 <canopus56(a)yahoo.com> >Subject: Re: [Utah-astronomy] nothing serious >To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> >Message-ID: <20050629234855.50030.qmail(a)web50902.mail.yahoo.com> >Content-Type: text/plain; charset=iso-8859-1 > >--- Kim Hyatt <kimharch(a)cut.net> wrote: ><snip> > > >>Rob described the Hartmann mask for me, "cardboard >>disc same size as OTA w/ 3 evenly spaced holes, >>placed over the front . . . >> >> > >My camera Hartmann mask looks like this - it's not >very precise - >http://www.astropix.com/HTML/I_ASTROP/I08/I0817/I0817.HTM > >See also Reeves trick of using a bright wide-double to >focus using the Hartmann mask and a star trail >exposure. >http://www.astrofoto.org/tips/focus/ > >You can also use a magnifier. Nikon makes (made) a >proprietary magnifier. I use a hand-loupe per >Lodriguss - >http://www.astropix.com/HTML/I_ASTROP/TOC_AP.HTM > >More difficult is the star trail test - I haven't done >this one - >http://www.astropix.com/HTML/I_ASTROP/I08/I0818/I0818.HTM > >See Jerry Lodriguss's focusing pages - >http://www.astropix.com/HTML/I_ASTROP/I08/I0812/I0812.HTM > >Enjoy - Canopus56 (Kurt) > > > > > >____________________________________________________ >Yahoo! Sports >Rekindle the Rivalries. Sign up for Fantasy Football >http://football.fantasysports.yahoo.com > > > >------------------------------ > >Message: 2 >Date: Wed, 29 Jun 2005 13:50:14 -1000 >From: Rob Ratkowski <ratkwski(a)hawaii.rr.com> >Subject: Re: [Utah-astronomy] nothing serious >To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> >Message-ID: <p0521060cbee8e28fb726(a)[192.168.0.100]> >Content-Type: text/plain; charset="iso-8859-1" ; format="flowed" > >Kim > > >You probably can find some DIY info >http://www.cloudynights.com/howtos2/hartman/hartman.htm >http://www.google.com/search?biw=769&hl=en&ie=ISO-8859-1&q=Hartmann+mask) >on line. Almost any size (w/i reason) hole works spaced 120s( apart. >Small holes for bright objects, somewhat larger holes for dim >objects. I do believe there are some Hartmann masks commercially >available also > > >Have fun >Rob > > > >------------------------------ > >Message: 3 >Date: Wed, 29 Jun 2005 18:08:28 -0600 >From: <astrodeb(a)charter.net> >Subject: Re: Re: [Utah-astronomy] nothing serious >To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> >Message-ID: <440397$cipre0(a)mxip14a.cluster1.charter.net> >Content-Type: text/plain; charset=ISO-8859-1 > >I had trouble focusing my DSLR back in December. I bought a Kwick Focus Hartmann mask with three circles from Kendrick Instruments. You can make one yourself if you can figure how to space the holes. I think there is an article on CloudyNights how to make one. I just didn't have the patience. > >When I used the Hartmann mask and a laptop computer to focus I had better success. Now I just need to solve my tracking problem. My M35 is on page 3 of my album. I may even purchase DSLR Focus. It is a neat computer program to achieve precise focus. Many people on the digital-astro group use it with success. > >Good Luck, > >Debbie > > >>From: "Kim Hyatt" <kimharch(a)cut.net> >>Date: 2005/06/29 Wed PM 05:00:01 MDT >>To: "Utah Astronomy" <utah-astronomy(a)mailman.xmission.com> >>Subject: Re: [Utah-astronomy] nothing serious >> >>I was going to ask, "What is a Hartmann mask?" but then I saw Rob's post. >>(Thanks Rob - great pics, too.) I still have a couple of questions: Does >>hole size matter? Distance from center? Distance of mask from refractor >>objective, or SCT corrector plate? >> >>Oh, and thanks for the help all. >> >> >>----- Original Message ----- >>From: "Michael Carnes" <michaelcarnes(a)earthlink.net> >>To: "Utah Astronomy" <utah-astronomy(a)mailman.xmission.com> >>Sent: Wednesday, June 29, 2005 4:23 PM >>Subject: Re: [Utah-astronomy] nothing serious >> >> >>| Kim, have you tried a Hartmann mask? >>| >>| -----Original Message----- >>| From: Kim Hyatt <kimharch(a)cut.net> >>| Sent: Jun 29, 2005 3:36 PM >>| To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> >>| Subject: [Utah-astronomy] nothing serious >>| >>| BlankHi all. Some of you know that I recently moved to Mt. Pleasant (and >>many of you probably don't care). I have a home a few miles east of town, >>with very DARK skies and great views of the valley and mountains. Our >>elevation here is about 6400 feet and there's very little light pollution, >>even from Mt. Pleasant itself, just three miles away. Hope some of you may >>be interested in visiting sometime. >>| >>| I've been experimenting with my Nikon D70 and I've captured some >>successful wide-angle images. Shortly I'll post them to the gallery. I have >>also recently tried some prime-focus pics, but I have trouble getting the >>focus correct. Anyone out there know some cool trick to focus accurately >>with a digital SLR? Keep in mind that you can't remove the camera back for a >>knife-edge focus. I also may try imaging with my 8-inch SCT, so tips would >>be helpful. >>| >>| Hope to rendezvous with y'all sometime. How about a star party at the old >>Skyline Drive site? Also, is Wolf Creek the pick for July's SLAS private >>star party? >>| >>| >>| Kim A. Hyatt, Architect >>| P.O. Box 124 >>| Mt. Pleasant, Utah 84647 >>| T: 435.462.9207 >>| F: 435/462.5013 >>| M: 801.631.5228 >>| kimharch(a)cut.net >>| >>| >>| >>| >>| _______________________________________________ >>| 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 >>| >>| ______________________________________________________________________ >>| This e-mail has been scanned by Cut.Net Managed Email Content Service, >>using Skeptic(tm) technology powered by MessageLabs. For more information on >>Cut.Nets Content Service, visit http://www.cut.net >>| ______________________________________________________________________ >>| >>| >> >> >> >>_______________________________________________ >>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 >> >> >> > > > >------------------------------ > >Message: 4 >Date: Wed, 29 Jun 2005 14:11:10 -1000 >From: Rob Ratkowski <ratkwski(a)hawaii.rr.com> >Subject: Re: [Utah-astronomy] nothing serious >To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> >Message-ID: <p0521060fbee8e8ee365e(a)[192.168.0.100]> >Content-Type: text/plain; charset="us-ascii" ; format="flowed" > >Mahalo Kurt for all the good sites to check focus. > > >Aloha >Rob > > > >------------------------------ > >Message: 5 >Date: Wed, 29 Jun 2005 17:39:13 -0700 (PDT) >From: Canopus56 <canopus56(a)yahoo.com> >Subject: Re: [Utah-astronomy] nothing serious >To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> >Message-ID: <20050630003913.16835.qmail(a)web50903.mail.yahoo.com> >Content-Type: text/plain; charset=iso-8859-1 > >--- Rob Ratkowski <ratkwski(a)hawaii.rr.com> wrote: > > >> Mahalo Kurt for all the good sites to check focus. >> >> > >Aloha kÃ¢ua astro - back at you. It wasn't clear to me >whether Kim was talking about focusing his camera >piggyback on the telescope or coupling the camera to >the telescope. If so, then we're also talking digital >fine tuning the focus using FWHM. I have less >experience with that. > >- Kurt > > > > >____________________________________________________ >Yahoo! Sports >Rekindle the Rivalries. Sign up for Fantasy Football >http://football.fantasysports.yahoo.com > > > >------------------------------ > >Message: 6 >Date: Wed, 29 Jun 2005 17:44:20 -0700 (PDT) >From: Chuck Hards <chuckhards(a)yahoo.com> >Subject: Re: Re: [Utah-astronomy] nothing serious >To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> >Message-ID: <20050630004420.54036.qmail(a)web30410.mail.mud.yahoo.com> >Content-Type: text/plain; charset=iso-8859-1 > > >Kudos to Deb for suggesting making your own mask. >Purchasing a commercial product as a quick solution to >every problem has always rubbed me the wrong way, as >some of you know. There's usually more satisfaction >in at least trying to be self-reliant. If you injure >yourself or set the house on fire, then by all means >go with the commercial item. ;) > >What did I miss while I was away for the last 5 >months? Anything good? > >C. > > >__________________________________________________ >Do You Yahoo!? >Tired of spam? Yahoo! Mail has the best spam protection around >http://mail.yahoo.com > > > >------------------------------ > >Message: 7 >Date: Wed, 29 Jun 2005 14:59:18 -1000 >From: Rob Ratkowski <ratkwski(a)hawaii.rr.com> >Subject: Re: [Utah-astronomy] nothing serious >To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> >Message-ID: <p05210611bee8f3ebcb59(a)[192.168.0.100]> >Content-Type: text/plain; charset="us-ascii" ; format="flowed" > >Hi Kurt > > >I think Kim was talking about focusing the camera while at prime >focus, tough w/o any help. The Hartmann mask works great and is easy >to construct and the there are the programs ............ > > >aloha from Maui >Rob > > > >------------------------------ > >Message: 8 >Date: Wed, 29 Jun 2005 19:21:20 -0600 >From: <astrodeb(a)charter.net> >Subject: Re: Re: [Utah-astronomy] nothing serious >To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> >Message-ID: <43vtna$vgd1fn(a)mxip06a.cluster1.charter.net> >Content-Type: text/plain; charset=ISO-8859-1 > >Try www.DSLRFocus.com >This is a neat program. Version 3.0 runs about $45. > >Debbie > > >>From: Rob Ratkowski <ratkwski(a)hawaii.rr.com> >>Date: 2005/06/29 Wed PM 06:59:18 MDT >>To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> >>Subject: Re: [Utah-astronomy] nothing serious >> >>Hi Kurt >> >> >>I think Kim was talking about focusing the camera while at prime >>focus, tough w/o any help. The Hartmann mask works great and is easy >>to construct and the there are the programs ............ >> >> >>aloha from Maui >>Rob >> >>_______________________________________________ >>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 >> >> >> > > > >------------------------------ > >Message: 9 >Date: Wed, 29 Jun 2005 19:38:22 -0600 >From: "Ken Harris" <kharrismar(a)earthlink.net> >Subject: [Utah-astronomy] Congratulations, Patrick!!! >To: Utah-Astronomy(a)mailman.xmission.com >Message-ID: <410-22005643013822656(a)earthlink.net> >Content-Type: text/plain; charset=US-ASCII > >Congratulations, Patrick, on being recognized by Bryce Canyon National Park for your VERY long service to the star-gazing public there. And, also, thank you for ALL THE GREAT WORK you do for us at SLAS & SPOC. Your contributions, both personal and financial, are unmatched, and, unfortunately, greatly unappreciated by many. But not unappreciated by me, and I suspect, quite a few more. Thanks, again! > > >Ken Harris >Great Salt Lake Shipmodeling & Research Society >NRG member >Salt Lake Astronomical Society > >------------------------------ > >_______________________________________________ >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 > >End of Utah-Astronomy Digest, Vol 28, Issue 13 >********************************************** > > > > > >

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Re: Re: [Utah-astronomy] nothing serious
by astrodeb＠charter.net 29 Jun '05

29 Jun '05

Try www.DSLRFocus.com This is a neat program. Version 3.0 runs about $45. Debbie > > From: Rob Ratkowski <ratkwski(a)hawaii.rr.com> > Date: 2005/06/29 Wed PM 06:59:18 MDT > To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> > Subject: Re: [Utah-astronomy] nothing serious > > Hi Kurt > > > I think Kim was talking about focusing the camera while at prime > focus, tough w/o any help. The Hartmann mask works great and is easy > to construct and the there are the programs ............ > > > aloha from Maui > Rob > > _______________________________________________ > 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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Re: Re: [Utah-astronomy] nothing serious
by astrodeb＠charter.net 29 Jun '05

29 Jun '05

I had trouble focusing my DSLR back in December. I bought a Kwick Focus Hartmann mask with three circles from Kendrick Instruments. You can make one yourself if you can figure how to space the holes. I think there is an article on CloudyNights how to make one. I just didn't have the patience. When I used the Hartmann mask and a laptop computer to focus I had better success. Now I just need to solve my tracking problem. My M35 is on page 3 of my album. I may even purchase DSLR Focus. It is a neat computer program to achieve precise focus. Many people on the digital-astro group use it with success. Good Luck, Debbie > > From: "Kim Hyatt" <kimharch(a)cut.net> > Date: 2005/06/29 Wed PM 05:00:01 MDT > To: "Utah Astronomy" <utah-astronomy(a)mailman.xmission.com> > Subject: Re: [Utah-astronomy] nothing serious > > I was going to ask, "What is a Hartmann mask?" but then I saw Rob's post. > (Thanks Rob - great pics, too.) I still have a couple of questions: Does > hole size matter? Distance from center? Distance of mask from refractor > objective, or SCT corrector plate? > > Oh, and thanks for the help all. > > > ----- Original Message ----- > From: "Michael Carnes" <michaelcarnes(a)earthlink.net> > To: "Utah Astronomy" <utah-astronomy(a)mailman.xmission.com> > Sent: Wednesday, June 29, 2005 4:23 PM > Subject: Re: [Utah-astronomy] nothing serious > > > | Kim, have you tried a Hartmann mask? > | > | -----Original Message----- > | From: Kim Hyatt <kimharch(a)cut.net> > | Sent: Jun 29, 2005 3:36 PM > | To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> > | Subject: [Utah-astronomy] nothing serious > | > | BlankHi all. Some of you know that I recently moved to Mt. Pleasant (and > many of you probably don't care). I have a home a few miles east of town, > with very DARK skies and great views of the valley and mountains. Our > elevation here is about 6400 feet and there's very little light pollution, > even from Mt. Pleasant itself, just three miles away. Hope some of you may > be interested in visiting sometime. > | > | I've been experimenting with my Nikon D70 and I've captured some > successful wide-angle images. Shortly I'll post them to the gallery. I have > also recently tried some prime-focus pics, but I have trouble getting the > focus correct. Anyone out there know some cool trick to focus accurately > with a digital SLR? Keep in mind that you can't remove the camera back for a > knife-edge focus. I also may try imaging with my 8-inch SCT, so tips would > be helpful. > | > | Hope to rendezvous with y'all sometime. How about a star party at the old > Skyline Drive site? Also, is Wolf Creek the pick for July's SLAS private > star party? > | > | > | Kim A. Hyatt, Architect > | P.O. Box 124 > | Mt. Pleasant, Utah 84647 > | T: 435.462.9207 > | F: 435/462.5013 > | M: 801.631.5228 > | kimharch(a)cut.net > | > | > | > | > | _______________________________________________ > | 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 > | > | ______________________________________________________________________ > | This e-mail has been scanned by Cut.Net Managed Email Content Service, > using Skeptic(tm) technology powered by MessageLabs. For more information on > Cut.Nets Content Service, visit http://www.cut.net > | ______________________________________________________________________ > | > | > > > > _______________________________________________ > 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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Estimating comet magnitudes (and the DI) (long)
by Canopus56 29 Jun '05

29 Jun '05

Although Comet 9P/Tempel will be well-covered by professional astronomers, the Deep Impact experiment will be visible to amateurs in the western United States and provides a good opportunity for amateurs to learn or practice the visual estimation of comet brightness. This post provides a beginner-intermediate level review of amateur techniques for visually estimating the magnitudes of comets using four methods - - Out-Out method, - Modified Out-Out method, - Extra-focal extinction method, and, - In-Out method. For beginners looking for Comet 9P finder charts, see Section V(A), near the bottom of this post. For advanced CCD astrophotographers, references to nearby Landolt photometry calibration stars and finder images are given in Section VI, near the bottom of this post. Although the non-nuclear Deep Impact experiment may be difficult to observe because it will be low in western continental U.S. sky, the experiment is a once-in-lifetime opportunity to potentially see a U.S. experiment involving high-explosive physics in space. 1962 was the last time that the United States conducted an even roughly analogous experiment - the Starfish Prime 1.4 megaton nuclear bomb detonation in low earth orbit. << http://en.wikipedia.org/wiki/Operation_Dominic_I_and_II ; http://www.atomicarchive.com/Photos/LANL/image56.shtml >>. By comparison, the non-nuclear Deep Impact kinetic collision will release energy equivalent to only 4.8 tons of TNT (1/300,000ths of Starfish Prime), or about the energy consumed by the average U.S. home in one month. << http://deepimpact.umd.edu/science/cratering.html >> (On the other hand, it's pretty amazing you might be able to 5 tons of TNT exploded from 7 1/2 light secs away.) I. Background information A. Measurements to estimate comet magnitudes. The methods described below are designed to visually measure the m1 magnitude of a comet. The m1 magnitude is the integrated brightness of coma and nucleus of the comet. m2 is the integrated brightness of the nucleus. Generally, this is accomplished by comparing the average visual surface brightness of the defocused comet with the visual surface brightness of a comparison star, defocused to the same diameter as the comet. The diameter of the comet should also be measured. The integrated surface brightness of an object is more useful when you also measure the area over which that brightness is spread. Most beginning amateurs have used similar information when observing small faint galaxies. Both the integrated magnitude and diameter of the galaxy are reported in astronomical catalogues. Typically, the diameter is measured by the drift method. (The drift method is not covered in depth by this note. See Section II.B.2.iii, below, for how to apply the drift method to Comet 9P.) B. Magnification applied. Low magnification (typically 30x-40x) is applied to make the measurement unless unpractical due to a small comet size. Low magnification is used because as higher levels of magnification are applied, the outer portions of the comet's coma fade below the surface brightness of the night sky. Higher magnification makes the comet appear smaller in diameter and with a lower total integrated magnitude than is seen with low magnification. C. Estimating in-focus and out-of-focus comet size. In-focus and out-of-focus comet diameters can be crudely measured using the drift method and a stopwatch. (Reports of Comet 9P/Tempel compiled by the International Comet Quarterly around June 16 list a magnitude around 10.0 and a diameter of 4 to 6 arcmins, about the size of a small globular cluster.) Even if you have not calibrated the drift rate of your low magnification eyepieces or do not have a low magnification eyepiece with a graduated reticule, the relative diameter of a defocused comparison star and the defocused comet can be estimated by measuring their drift rate in seconds, assuming the comparison objects are at nearly the same declination. See Section II.B.2.iii, below. D. Adjusting estimated magnitude for atmospheric extinction. Magnitudes can be described as either apparent - that is unadjusted for the effect of atmospheric extinction - or zenithal - that is adjusted for the effect of atmospheric extinction. Because there is less air mass at the zenith, magnitudes measured when an object is close to the zenith are higher than those measured when the object is near the horizon. Typically, the magnitude of the defocused comet is compared to the magnitude of a defocused comparison star. The magnitude of the comparison star is looked-up in a reputable catalogue - like the Tycho 2 catalogue - and its "V" band magnitude is used to describe the integrated magnitude of the comet. If the comparison star and the comet are in same part of the sky and are dimmed by the same level of atmospheric extinction, then the catalogue "V" band magnitude is the true zenithal magnitude of the comparison star and comet. If the comparison star is significantly higher or lower than the comet, then the catalogue "V" band magnitude of the comparison star needs to be adjusted for atmospheric extinction to yield the true zenithal magnitude of the comet and comparison star and/or the apparent magnitude of the comet. The atmospheric extinction adjustment is described below in Section III, below. E. Number of measurements. Although for pleasure observing, one measurement often is taken, the usual practice is to make several measurements using various sets of comparison stars and then the results are averaged. F. Confirming doubtful magnitudes. If in doubt, the V magnitude of a star can be verified using the Centre de DonnÂes astronomiques de Strasbourg (CDS) Simbad database query form at << http://simbad.u-strasbg.fr/sim-fid.pl >>. II. Magnitude measuring methods A. Out-Out Method (comet defocused out; comparison star defocused out; a.k.a. the VBM - Van Biesbroeck-Bobrovnikoff-Meisel method) 1) Best used for. The Out-Out method is best used when (1) there is a higher contrast between the comet and the background night sky and (2) comparison stars are available within the same field of view or within an adjacent eyepiece field of view. (If Comet 9P/Tempel brightens to a potential high magnitude of 7.0, this may be the best method to visually measure the brightness of the impact.) 2) Procedure. i) Apply the lowest usable magnification. ii) Defocus (either inside or outside focus) until - A) the coma and nucleus of the comet are a uniform circular brightness, and, B) the diameter of the defocused stars in the field of view and the defocused comet are similar. iii) Find a defocused star in the field of view slightly brighter than the defocused comet. Find a defocused star in the field of view slightly dimmer than the defocused comet. iv) Lookup the comparison stars' "V"-band magnitude in a reputable catalogue, like the Tycho 2 catalogue. v) If needed, adjust for atmospheric extinction as described below. vi) The comet's zenithal estimated magnitude is the midpoint between the adjusted magnitudes of the two comparison stars. Report your magnitudes as either apparent or zenithal adjusted. B. Modified Out-Out Method (comet defocused out; comparison star defocused out; a.k.a. the Morris-O'Meara method) 1) Best used for. Same as the Out-Out method. The modified Out-Out method is almost identical to the Out-Out method, but it attempts to compensate for the fact that appropriate comparison stars are often not available in the same field of view as the comet. 2) Procedure The procedure for the modified Out-Out method is the same as for the Out-Out method, but - i) the angular size and brightness of the defocused comet is memorized. ii) The telescope or binoculars then is slewed to a new field-of-view containing the comparison star. iii) The comparison star is defocused to the memorized diameter of the defocused comet. This procedure involves a subjective measurement of the diameter of the defocused comet and the comparison star. One modification that might improve the measurement of the diameter of the defocused objects is to measure their diameter using the drift method. Place with one side of the object against the field stop, turnoff any drive motors on your telescope's mount, and measure the numbers seconds it takes for the object to drift out of the field of view, using a stopwatch. When the comet and comparison star are defocused so they have nearly the same drift rate (assuming they are at nearly the same altitude), then they have the same diameter. At the point of impact, the Comet 9P will be at approximately J133751.52 -093400.5. At -09Ã¸34' declination, the drift rate of celestial objects will be 0.247 arcminutes per second or 14.79 arcseconds per second. Table 1.0 gives the size in arcminutes for various seconds of drift at 9Ã¸30' of declination: Table 1.0 - Object size from drift rates at 9Ã¸30' declination Sec Rate " Size " Size ' 12 14.79 177 3.0 14 14.79 207 3.5 16 14.79 237 4.0 18 14.79 266 4.4 20 14.79 296 4.9 22 14.79 325 5.4 24 14.79 355 5.9 26 14.79 385 6.4 28 14.79 414 6.9 30 14.79 444 7.4 32 14.79 473 7.9 34 14.79 503 8.4 36 14.79 532 8.9 38 14.79 562 9.4 40 14.79 592 9.9 42 14.79 621 10.4 Defocused comparison stars on the celestial equator will have a size of 15 arcseconds for second of drift or as listed in the following table of declinations 0 to 9 degrees: Table 2.0 - Drift rates per second for declinations 0 deg to -8 degs Dec Drift rate arcsec per sec +0 15.00 -1 15.00 -2 14.99 -3 14.98 -4 14.96 -5 14.94 -6 14.92 -7 14.89 -8 14.85 -9 14.82 C. Extra-focal extinction method. (Comet and comparison star defocused until they disappear against the brightness of the background night sky; a.k.a. the Beyer method) 1) Best used for. Best used for comets that have a low contrast between the comet and the background night sky. This occurs with fainter comets and in suburban/rural and rural/dark transition skies with low light pollution. (Comet 9P/Tempel 1, before the Deep Impact experiment fits this category. Reports of Comet 9P/Tempel compiled by the International Comet Quarterly around June 16 list a magnitude around 10.0.) 2) Procedure i) The comet is defocused until it just disappears against the background night sky, as seen in the eyepiece. Then back-in the focus until the disk of the defocused comet is faintly visible. ii) Estimate or measure (using the drift method) the angular size of the disk. iii) A comparison star is located that disappears against the background night sky at nearly the same angular size when defocused. Alternatively, two defocused stars, one slightly brighter and one slightly dimmer than the defocused comet are located. iv) Lookup the comparison stars' "V"-band magnitude in a reputable catalogue, like the Tycho 2 catalogue. v) If needed, adjust for atmospheric extinction as described below. vi) The comet's zenithal estimated magnitude is the midpoint between the adjusted magnitudes of the two comparison stars. D. The In-Out Method (comet in-focus, star out-of-focus; a.k.a. the VSS method - Vekhsvyatskij-Steavenson-Sidgwick method) 1) Best used for. Best used for higher contrast comets. 2) Procedure i) Guess or estimate the m1 surface brightness of the comet. ii) Measure or memorize the diameter of the comet. iii) Locate nearby comparison stars in a catalogue, usually 1 or 2 magnitudes brighter than your estimate. iv) Defocus the comparison star to the same diameter as the in-focus comet. v) Lookup the comparison stars' "V"-band magnitude in a reputable catalogue, like the Tycho 2 catalogue. v) If needed, adjust for atmospheric extinction as described below. vi) The comet's zenithal estimated magnitude is the midpoint between the adjusted magnitudes of the two comparison stars. III. Atmospheric extinction adjustment International Comet Quarterly table (Green 1992) provides rough correcting values for atmospheric extinction based on the kilometers of the observing point above sea level: Table 3.0 "Average" Atmospheric Extinction in Magnitudes for Various Elevations Above Sea Level (h, in km) (Excerpts from Green 1992) z h = 0 h = 0.5 h = 1 h = 2 h = 3 01 0.28 0.24 0.21 0.16 0.13 10 0.29 0.24 0.21 0.16 0.13 20 0.30 0.25 0.22 0.17 0.14 30 0.32 0.28 0.24 0.19 0.15 40 0.37 0.31 0.27 0.21 0.17 45 0.40 0.34 0.29 0.23 0.19 50 0.44 0.37 0.32 0.25 0.21 55 0.49 0.42 0.36 0.28 0.23 60 0.56 0.48 0.41 0.32 0.26 62 0.60 0.51 0.44 0.34 0.28 64 0.64 0.54 0.47 0.37 0.30 66 0.69 0.59 0.51 0.39 0.32 68 0.75 0.64 0.55 0.43 0.35 70 0.82 0.70 0.60 0.47 0.39 72 0.91 0.77 0.66 0.52 0.43 74 1.02 0.86 0.74 0.58 0.48 76 1.15 0.98 0.84 0.66 0.54 78 1.34 1.13 0.98 0.76 0.63 80 1.59 1.34 1.16 0.91 0.74 The "z" value is the degrees from zenith to the celestial object. So z=80 is 20 degrees altitude above the local horizon. For example, if the "V" band catalogue magnitude of your comparison star is 7.5, the star is located 30 degrees above the horizon (or 60 degrees from the zenith), the observer is at sea level, and the comet and the comparison star are nearly at the same altitude above the horizon, then the true zenithal brightness of the comet is v7.5 and its apparent brightness is v6.9 (7.5-0.56). If the comet (at 40 degrees altitude) is higher than the comparison star (at 30 degrees altitude), the comet's true zenithal brightness is 7.4 (7.5+0.44-0.56). The 0.1 magnitude represents the additional extinction between 30 and 40 degrees altitude. Conversely, if the comet (at 30 degrees altitude) is lower than the comparison star (at 40 degrees altitude), the comet's true zenithal brightness is 7.6 (7.5-0.44+0.56). The 0.1 magnitude adjusts for the additional extinction between 40 and 30 degrees altitude. IV. Describing the density profile of the comet The following descriptions, from << http://cometforum.planetaclix.pt/meth.html >> may be of use in describing the density profile of a comet - Degree of concentration number Description DC=0 Coma completely uniform in brightness. Flat brightness profile across the coma. DC=1 Central coma possibly very slightly brighter than outer coma. DC=2 Central zone slightly brighter. Some brightness in balance across the coma. DC=3 Central coma definitely brighter than the outer coma. Coma still very diffuse. DC=4 Central zone outstandingly brighter; frequently two distinct levels of brightness within the coma. Moderately condensed. DC=5 Still more condensed; the central condensation strongly influences m1, hampering the use of the In-out method. DC=6 Central zone very prominent. Steep brightness profile; most of the light is in the central condensation. DC=7 Sharp peeked brightness profile. The outer coma influences very little the total brightness. DC=8 The coma is quasi-starlike, just slightly diffuse; the rest of the coma brightness is irrelevant to the total brightness. DC=9 Stellar coma, or small disk. No diffuse coma. An easy method for beginners to apply the DC scale is to make only rough estimates using levels 0 (no coma), 3 (central coma brighter than outer coma), 6 (prominent central zone), and 9 (comet looks like a star). V. Comet 9P/Tempel - Finding and stellar magnitude charts A. Finder charts The "official" Deep Impact site finder chart - http://deepimpact.umd.edu/gallery/Finder_Charts.html Detailed finders at Astrosite Groningen with stellar magnitudes - http://www.shopplaza.nl/astro/comets/9pcharts/comets.htm http://www.shopplaza.nl/astro/comets/9pcharts/9PCH11.png http://www.shopplaza.nl/astro/comets/9pcharts/9PCH1C.2.png Author's finder charts to mag 12 - Topocentric position of Salt Lake City, Utah - RA/Dec Chart: http://members.csolutions.net/fisherka/astronote/finder/Comet9PFinder.gif Alt-Az Chart (for 111 W, 41 N): http://members.csolutions.net/fisherka/astronote/finder/Comet9PFinderAltAz.… B. Some practical tips on finding Comet 9P/Tempel 1 At dusk, on any basic star chart find the line between alpha Virgo (Spica) and gamma Virgo. Currently Jupiter is just southwest of gamma Virgo. Mid-way between gamma Virgo-Jupiter and Spica is theta Virgo (v4.4). Your first finder line is between Spica and theta Virgo. Next, using binoculars or your finder scope, establish a second reference line about 5 degrees north of your first reference line. The second reference line is defined by 82 Virgo (v5.0), 74 Virgo (v4.7), 72 Virgo (v6.1), 66 Virgo (v5.8) and 65 Virgo (v5.8). Comet 9P/Tempel 1 is between these two reference lines as indicated on the above charts for any given night. C. Recent magnitude data Amateur observations are compiled by the International Comet Quarterly at: << http://cfa-www.harvard.edu/iau/icq/CometMags.html >> Some recent observations for Comet 9P from the ICQ website are reproduced here: Decimal_day; V_mag; Diameter_arcsec; (Observer, OP, scope, camera) 2005 June 16.06, 09.9, 6.0' (J. J. Gonzalez, Leon, Spain, 25x100 binoculars); 13.92, 10.1, 4.0' (A. Baransky, Bucha, Ukraine, 0.20-m reflector); 13.00, 11.1, +1.8' (T. Scarmato, Calabria, Italy, 0.25-m reflector + CCD); 11.92, 10.0, 4.5' (A. Baransky, Pylypovychi, Ukraine, 0.36-m reflector); 10.95, 10.6, 4.0' (C. Gros, Besancon, France, 20x100 binoculars); 10.90, 11.2, +1.8' (T. Scarmato, Calabria, Italy, 0.25-m reflector + CCD + R_c filter); 10.03, 09.4, 6.0' (J. J. Gonzalez, Leon, Spain, 11x80 binoculars); VI. Nearest Landolt star fields and CCD calibration stars (Count=5 stars) Source and more photometry information: http://www.cfht.hawaii.edu/ObsInfo/Standards/Landolt/ 1) G14 55 JPos 13 28 22 -02 21 28 V_mag 11.34 Link to SAO area chart - http://www.cfht.hawaii.edu/ObsInfo/Standards/Landolt/G14.gif 2) 105 505 Jpos 13 35 24 -00 23 47 V_mag 10.27 Link to SAO area chart - http://www.cfht.hawaii.edu/ObsInfo/Standards/Landolt/SA105.gif 3) 105 815 Jpos 13 40 04 -00 02 19 V_mag 11.45 Link to SAO area chart - http://www.cfht.hawaii.edu/ObsInfo/Standards/Landolt/SA105.gif 4) +2 2711 Jpos 13 42 20 +01 29 58 V_mag 10.37 Link to SAO area chart - http://www.cfht.hawaii.edu/ObsInfo/Standards/Landolt/PLUS2.gif 5) HD121968 Jpos 13 58 51 -02 55 38 V_mag 10.25 Link to SAO area chart - http://www.cfht.hawaii.edu/ObsInfo/Standards/Landolt/HD121968.gif Enjoy - Canopus56 (Kurt) References: Green, Daniel. July 1992. Correcting for Atmospheric Extinction. International Comet Quarterly. 14:55 << http://cfa-www.harvard.edu/cfa/ps/icq/ICQExtinct.html >> Green, Daniel. Oct. 1996. International Comet Quarterly. 104:18 Kraus, Herbert. Nov. 27, 2004. Drift Testing to Determine Your Eyepiece's True Field of View << http://www.astromart.com/articles/article.asp?article_id=188 >> Levy, David. 2003. David Levy's Guide to Observing and Discovering Comets. Cambridge Univ. Press. At pp. 132-134 Pereira, A and Vitorino, C. ____. The visual photometry of comets. << http://cometforum.planetaclix.pt/meth.html accessed June 2005 >> ____________________________________________________ Yahoo! Sports Rekindle the Rivalries. Sign up for Fantasy Football http://football.fantasysports.yahoo.com

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nothing serious
by Kim Hyatt 29 Jun '05

29 Jun '05

BlankHi all. Some of you know that I recently moved to Mt. Pleasant (and many of you probably don't care). I have a home a few miles east of town, with very DARK skies and great views of the valley and mountains. Our elevation here is about 6400 feet and there's very little light pollution, even from Mt. Pleasant itself, just three miles away. Hope some of you may be interested in visiting sometime. I've been experimenting with my Nikon D70 and I've captured some successful wide-angle images. Shortly I'll post them to the gallery. I have also recently tried some prime-focus pics, but I have trouble getting the focus correct. Anyone out there know some cool trick to focus accurately with a digital SLR? Keep in mind that you can't remove the camera back for a knife-edge focus. I also may try imaging with my 8-inch SCT, so tips would be helpful. Hope to rendezvous with y'all sometime. How about a star party at the old Skyline Drive site? Also, is Wolf Creek the pick for July's SLAS private star party? Kim A. Hyatt, Architect P.O. Box 124 Mt. Pleasant, Utah 84647 T: 435.462.9207 F: 435/462.5013 M: 801.631.5228 kimharch(a)cut.net

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Space camera flaw traced to earthly mirror
by daniel turner 29 Jun '05

29 Jun '05

The optical flaw that blurred the vision of NASAÂs comet-smashing Deep Impact probe has been tentatively diagnosed as the result of overlooking a simple law of physics, sources familiar with the investigation have told MSNBC.com. But despite widespread rumors that the same flaw had also infected the cameras for other space probes, including a Mars orbiter now on the launch pad at Cape Canaveral and a mission to Pluto due for launch next January, these sources insist that the focus problem was unique to Deep Impact Â and has already been solved. As Deep Impact fixes its sights to send out its Impactor subsatellite for a planned collision with Comet Tempel 1 on July 4, space engineers back on Earth have been literally "fixing the sight" on the main spacecraft's High Resolution Imager, which is intended to relay the best pictures of the resulting debris cloud and crater. Shortly after Deep Impact's launch in January, engineers found that the camera was sending slightly blurred test images back to Earth, but now they have succeeded in developing mathematical methods to sharpen the focus. In the rush to repair the damage, discovering the original cause of the focusing flaw was a less critical task than being Âfocused on the success of the mission,Â explained Lindley Johnson, the mission's program executive at NASA Headquarters in Washington. ÂIÂm the person who keeps track of everything and works all the issues,Â he explained by telephone. ÂThere hasnÂt been a complete investigation,Â he said, Âand nothingÂs been signed off.Â However, he said he believes the problem, which arose at the Ball Aerospace facility in Boulder, Colo., is now understood. Johnson explained that the imaging system undergoes final calibration by projecting a simulated comet image into the optics, and a standard glass mirror 8 inches (20 centimeters) in diameter was used to reflect light from the image projector and the flight imager. ÂThe flat mirror is the suspected cause,Â Johnson said. Low temperatures warped test mirror The mirror became warped during the test because of the need to simulate the low temperatures that would be experienced in space, almost twice as far from the sun as Earth is. ÂThe test chamber shroud was flooded with liquid nitrogen to bring the temperature of the detectors down to the flight operating temperatureÂ of 225 degrees below zero Fahrenheit (-143 degrees Celsius), Ball Aerospace spokesman David Beachley explained. INTERACTIVE Â Inside a comet The secrets within a dirty snowball As a result, the mirror bowed slightly concave, bringing the test image into perfect focus about a quarter of an inch (7.4 mm) in front of the design position. The imagerÂs 12-inch-diameter (30-centimeter-diameter) mirror was in perfect shape, and the unit was calibrated by moving the light detector array farther down the telescope tube. Once the image appeared to be in perfect focus, the hardware was firmly fixed in position for flight. ÂThis is not a problem in the figure of the mirror,Â Johnson explained, referring to the actual parabolic shape of the reflector and implicitly contrasting his spacecraftÂs problem with the focus flaw that cursed the Hubble Space Telescope before astronauts installed corrective optics. ÂThis is a problem of structural placement,Â he said. Investigators still need to determine what it was about the material properties of the flat mirror that caused the front face to contract in the cold more than the back face, creating a very small curvature. They also will be asking whether the required correction in the imagerÂs array position was larger than the expected uncertainty and should have been recognized as an indicator of trouble in the test rig. --------------------------------- Yahoo! Sports Rekindle the Rivalries. Sign up for Fantasy Football

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New album photos posted
by Chuck Hards 28 Jun '05

28 Jun '05

Hi all, I posted a few new (I hope) photos to my gallery page tonight. I've learned a little (emphasis on little) more about image processing since my last posting of a Hale-Bopp photo, hopefully there is more tail detail visible this time. C. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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New Image - M27 The Dumbell Nebula
by Tyler Allred 28 Jun '05

28 Jun '05

Hi all. I finally got a chance last night to use my new Tak CN-212 for a little imaging. I used the scope in the Newtonian configuration and did a little Hydrogen-alpha work combined with RGB data. Here is the result: Low Resolution Thumbnail http://www.utahastronomy.com/album16/M27_HaRGB_Best High Resolution Image http://www.utahastronomy.com/album16/M27_HaRGB_Best?full=1 Exposure details are included with the images. Take a look and let me know what you think. Comments and suggestions are always welcome! Cheers, Tyler

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