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

Mnemonic for remembering the progression of the ecliptic constellations
by Canopus56 25 Nov '05

25 Nov '05

Something developed in another newsgroup recently. May be of use for intermediate school star parties - Vir Very Lib Large Sco Scopes, Sgr Skilled Cap Collimation Aqu And Psc Preposterous Ari Aperatures, Tau Throw Gem Great Can Collected Leo Light - Canopus56 __________________________________ Start your day with Yahoo! - Make it your home page! http://www.yahoo.com/r/hs

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Happy Thanksgiving
by Chuck Hards 23 Nov '05

23 Nov '05

I wish all members of the Utah-astronomy list a sincere Happy Thanksgiving Day holiday. I plan on eating more turkey than I really should, then watching a movie or three with my family on the big screen TV...hope I can stay awake! C. __________________________________ Start your day with Yahoo! - Make it your home page! http://www.yahoo.com/r/hs

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RE: [Utah-astronomy] Re: Flat Field Frames
by Dale Hooper 23 Nov '05

23 Nov '05

There are also a couple other little complications that may or may not apply to anyone here: 1. If you are doing photometry, your light box needs to have a "broadband white light" type spectra. I.e. LED's can give you trouble because they are much stronger at specific spectral lines. 2. If you use an SCT with a dew shield or some other telescope where you have a dew shield, etc. - you need to place the light box over the dew shield. Otherwise, you've modified the optical train and your flat frame might have some "issues". Clear skies, Dale. > -----Original Message----- > From: utah-astronomy-bounces+dale.hooper=sdl.usu.edu(a)mailman.xmission.com > [mailto:utah-astronomy- > bounces+dale.hooper=sdl.usu.edu(a)mailman.xmission.com] On Behalf Of > Canopus56 > Sent: Tuesday, November 22, 2005 1:06 PM > To: Utah Astronomy > Subject: Re: [Utah-astronomy] Re: Flat Field Frames > > --- Chuck Hards <chuckhards(a)yahoo.com> wrote: > > Kurt, try this approach: > > http://www.electrolamp.com/elpanel.html > > Thanks for referral. I didn't see any prices on the > Epanel. > > On the other hand, Patrick's piece of white board with > a low flux light seems pretty simple and low-tech. > > <snip> > > I've often thought about using the red material and > > lining the edge of my eyepiece and accessory cases > > with a strip of it, or making a chart illuminator > > from it. > > I hadn't thought of that alternate use for white field > box. A simple piece of Roscolux #83 diffuse or #27 > red cut to shape and held between two pieces of black > artist foam board should do the trick. > > I was also thinking about trying to use the white > light box for holographic collimination of a Newt's > secondary mirror. It would be the white light box > with a piece of clear plastic printed with a 1/4" > grid. > http://web.telia.com/~u41105032/holographic/holographic.htm > > - Canopus56 > > > > > > __________________________________ > Yahoo! Mail - PC Magazine Editors' Choice 2005 > http://mail.yahoo.com > > _______________________________________________ > 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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M52- Cassiopeia's richest open cluster
by astrodeb＠charter.net 23 Nov '05

23 Nov '05

I justed posted my M52 image taken on Sunday night. It is located at: http://www.utahastronomy.com/astrodeb/M52 The winter sky is just full of these rich clusters. Debbie

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Re: Re: [Utah-astronomy] M52- Cassiopeia's richest open cluster
by astrodeb＠charter.net 23 Nov '05

23 Nov '05

It wasn't too cold that night until I packed it in. I did a total of 21 minutes for that picture. I wanted to shoot it before the moon rose. I may do a wide-field picture with my last roll of film next month. Debbie > > From: Joe Bauman <bau(a)desnews.com> > Date: 2005/11/23 Wed AM 07:51:33 MST > To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> > Subject: Re: [Utah-astronomy] M52- Cassiopeia's richest open cluster > > Very nice, Deb -- I could just feel the cold night air while looking > at it. -- 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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Re: Re: [Utah-astronomy] Flat Field Frames
by astrodeb＠charter.net 23 Nov '05

23 Nov '05

Joe, I had to run to the store to get the turkey so I didn't get a chance to reply to your question. My book "A Practical Guide to CCD Imaging" that I recently acquired says "The flat field takes into account the gain irregularies of the array's different pixels and the optical transmission irregularities, in particular, vignetting and the presence of DUST in the light path. We must therefore produce a flat field for each optical assembly and, if possible, at each observation session, since dust can appear, disappear, or move from one day to another. Since it is imperative not to change the optical configuration between the flat field and the image acquisitions, we can work with a maximum of two optical configurations per night: one at the night's start, for which we produce flat fields in the evening, the other at the end of the night, for which we produce the morning flat fields before sunrise (which requires some self-sacrifice, ie sleep). The flat field must be produced after focusing, in order for the light path to be the same during the flat field and the nocturnal sky image. Thus, the focusing is done on the stars, and the flat field must be finished before the first stars appear! The solution to this paradox consists in keeping the camera mounted from one night to another, or to accurately find the position that corresponds to the focus. In all cases, the first night's flat field, produced on an approximate adjustment, will not necessarily be very satisfying." This is all fine and dandy if you have an observatory or set up at a remote site so you don't have to worry about equipment being stolen. I don't feel confortable leaving my camera or telescope set up all night. Is it possible to focus on Venus or Jupiter before it gets dark? Then take the flats and download them directly to the computer. I know SBIG recommends putting a white T-shirt over the optical system but will there be enough light available once you get your camera focused? I didn't get a chance to try this Sunday night because I filled up my memory card. Hope this helps to clarify flat fields. I'm just trying to figure out the best way to do it with my portable setup. Debbie > > From: Joe Bauman <bau(a)desnews.com> > Date: 2005/11/22 Tue AM 10:53:59 MST > To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> > Subject: Re: [Utah-astronomy] Flat Field Frames > > Many thanks! > > -- Black skies! -- 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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Fwd: stolen eyepieces alert...
by Richard Tenney 23 Nov '05

23 Nov '05

--- Darren Davis <darren(a)virtualvoodoo.com> wrote: > From: Darren Davis <darren(a)virtualvoodoo.com> > To: uvaa(a)mailman.xmission.com > Date: Tue, 22 Nov 2005 22:15:43 -0700 > Subject: [UVAA] stolen eyepieces alert... > > Last night, I took my telescope out to look at the > stars with some visiting > friends, only to discover that the meade hard case > containing all of my > lenses had been stolen from my garage!! (along with > several tools). It's > been a month since last used my scope, so it must > have happened during the > past 30 days, probably between Oct 29 adn Nov 12 > when I was overseas on > business. > > I doubt that the average thief would have much use > for a set of astronomy > lenses, so I suppose he/she will attempt to sell > them. If anyone comes > across a complete set of Meade Plossell (yellow > letters) lenses + a second 26 > mm and 9 mm (blue letters) lenses for sell in an ad > or pawn shop, let me > know. > > One of the lenses has a very obvious flaw visible > when looking through the > scope, so it won't be too hard to identify if it > turns up. > > Thanks, > > Darren > > _______________________________________________ > UVAA mailing list > UVAA(a)mailman.xmission.com > http://mailman.xmission.com/cgi-bin/mailman/listinfo/uvaa > __________________________________ Start your day with Yahoo! - Make it your home page! http://www.yahoo.com/r/hs

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Re: Flat Field Frames
by Chuck Hards 22 Nov '05

22 Nov '05

Kurt, try this approach: http://www.electrolamp.com/elpanel.html This particular site lists material with an odd voltage (but low current consumption, a power supply run from a car battery would be easy), but I know that it is made to operate from low DC voltages as well. You could make a light source as small as a dust cover that fits over the aperture, no more than an inch or so thick, and completely evenly illuminated. In fact it could double as a dust cap. If you can find the low-voltage material you could even dispense with the power supply. If made like this it wouldn't be a problem for even an observer right next to you, you'd leak no light at all. This thin sheet material can even be cut to odd sizes (like round), as long as you don't cut-off the power contact areas. The samples I have seen are about as thick as two or three document protector sheets pressed together. I've often thought about using the red material and lining the edge of my eyepiece and accessory cases with a strip of it, or making a chart illuminator from it. Some of the low-voltage material changes color as you vary the voltage. > From: Canopus56 <canopus56(a)yahoo.com> > Subject: Re: [Utah-astronomy] Flat Field Frames > I'm new to this myself but happen to be in the > middle > of building a white light box, this evening in fact. > > Twilight is fine, but what happens when you arrive > after dark? __________________________________ Yahoo! Mail - PC Magazine Editors' Choice 2005 http://mail.yahoo.com

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Flat Field Frames
by astrodeb＠charter.net 22 Nov '05

22 Nov '05

For those of you that do CCD imaging I was wondering how you take the flat field frames. I've heard that that a twilight sky makes a nice flat frame but the camera has to be focused first. Without stars to focus, this is quite difficult. I was going to try putting some printer paper over the dewshield but I filled up my memory card before I had a chance to try it. SBIG recommends a white T-shirt. Has anyone tried this before? I'm looking for ideas how to incorporate flat field frames into my images to remove dust and other artifacts that accumulate on the lens. Clear Skies, Debbie

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Re: Re: [Utah-astronomy] Flat Field Frames
by astrodeb＠charter.net 22 Nov '05

22 Nov '05

But won't focus change just slightly from night to night because of different thermal conditions? Richard, from Stellar Technologies International says to check the focus when changing to a different target because the telescope may cool and focus may change slightly. I guess you could reuse flat frames if the imaging nights are spaced close together but I would redo them from month to month. Debbie > > From: Patrick Wiggins <paw(a)trilobyte.net> > Date: 2005/11/22 Tue AM 10:40:57 MST > To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> > Subject: Re: [Utah-astronomy] Flat Field Frames > > Joe Bauman wrote: > > I hope someone could explain more about flat frames. I know what they're > > supposed to do. My question is, why isn't it good enough to take one set > > of flat frames, and then have them to reuse forever? Or is it good > > enough? Thanks, Joe > > Morning Joe, > > This comes up on the Software Bisque groups from time to time. > > My understanding is that you can resuse flats _provided_ the focus is at > the exact same place and the position of the camera and any focal > reducers are in the exact same position. > > But if any of that changes, even a little, a new flat must be made. > > Patrick > > _______________________________________________ > 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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