----- Original Message ----- From: "Ed Cannon" <ecannon@mail.utexas.edu> To: <SeeSat-L@satobs.org> Sent: Thursday, January 24, 2002 8:55 PM Subject: Re: Corrected: A flasher? Can you identify it? > Richard Crisp wrote: > > > ... caught what I believe was a flasher transiting M1, The Crab > > Nebula. > > Neat photo! Thanks, I'm glad that I can find a use for otherwise spoiled images > > I see on Richard's Web page that Ed Light has already ID'ed it as > Raduga 33 (23794, 96-010A). Using Oakland, CA, I got the same one, > but mainly I wanted to add that Raduga 33 is definitely tumbling > and is known to flash very brightly on occasion, sometimes at quite > a distance. Jack Schmidling got a shot of something that thus far has not been ID'd (http://user.mc.net/arf/m1.htm , look down the page a bit). I believe he got a flasher, but his track shows a rather prominent discontinuity as if it suddenly moved to one side. Now a guiding error or some other transient could have displaced the image during the exposure. If the sat track is a lot brighter than anything else in the image then the image may not show the bump except for the bright sat track. So that's one theory of what explains the zig-zag in Jack's image. Another theory is that the surface of the flasher is such that it concentrates the light to one side of it and that as it rotated past a critical point the light was cast to one side but still facing toward the Earth. The idea is that it would "bulge" the light to one side or the other of the track as it rolls along (somewhat like a lighthouse). I believe that it could make an apparent discontinuity in the track. In fact my image of M1 shows a bit of a "bumpiness" that tends to make the line look a bit crooked. Then there is the combination of these effects and the discrete pixel "snap to" problem: there are only discrete "squares" that comprise the image. When the track intersects these on a shallow angle, you get a breaking up effect of the line as we've all seen on a TV screen when a fellow has a striped tie etc. > > For future reference, I'll venture to suggest that in order to get > really precise identifications, a fairly specific observing location > should be provided -- at least a specific city (unless it's "Los > Angeles, Calif.", which is too big!), if not actual coordinates. Sure, I am in Castro Valley, Ca, very near Oakland. > > By the way Richard, what were the specifics of the photo of IC 1795? Taken at 10:28pm on Oct 13, 2001 Pacific Daylight time (0528UTC on 10/24/2001) taken about 10 miles east of Morgan Hill, California. IC1795 was the target I was acquiring. See my web page again,. I uploaded the high resolution version of the IC1795 image and it shows several tracks. In fact not all are parallel http://www.rdcrisp.darkhorizons.org/Tracks_page.htm I also uploaded another multiple track image, but did not have but the 3x3 binned version (I caught it while focusing nearby M33) > Side-by-side tracks are suspicious -- see the multiple-thread, > multiple subject discussions in September and October 1999 of a > Sky & Telescope photograph with parallel tracks through M42, the > Orion Nebula, beginning with Jay Respler's post, "SAT TRACK PHOTO": Sometimes I wonder if they are due to internal reflections within the camera and or optical system. rdc > > http://www.satobs.org/seesat/Sep-1999/0251.html > > The discussion continued into October, e.g., with Rob Matson's post, > "Mystery tracks through M42": > > http://www.satobs.org/seesat/Oct-1999/0067.html > > Ed Cannon - ecannon@mail.utexas.edu - Austin, Texas, USA > > ----------------------------------------------------------------- > Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' > in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org > http://www.satellite.eu.org/seesat/seesatindex.html >
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