**Previous message:**Jonathan T Wojack: "Re: Morning Pass Of ISS/Venus"**Maybe in reply to:**Matson, Robert: "Satellite visual magnitude equations"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]

> Yes -- the equations are specific to the example you > gave: an object at 90-degree phase. > > > > It must be possible for an object to be at 1600km distance in more > than > > one spot. Or perhaps the phase angle is irrelevant? > > Of course phase is VERY important. I deliberately > excluded the phase-dependence from the equation > because your example did not require it. Actually, my question had absolutely nothing to do with the Mars Odyssey Rocket. I am just trying to learn about the math involved in satellites. This summer, I hope to become an expert on the material covered in "The Fundamentals of Astrodynamics". >I posted > a full equation w/phase-dependence on Seesat many > months ago, but I'll include one here: > > Mag = Std. Mag - 15 + 5*LOG(Range) - > 2.5*LOG(SIN(B) + (pi-B)*COS(B)) > > where Range is in km, and B is in radians and measures > the angle from the sun to the satellite to the observer. > At full phase, B is 0; at new phase, B is pi (i.e. > satellite transiting the sun). Don't worry, I know more than enough about radians. > I want to emphasize that this is the correct equation for > a spherical satellite with a perfectly Lambertian surface. > Of course, few satellites are spherical, and none have > perfectly Lambertian surfaces. Still, it is a good > approximation when you don't know the orientation of > a satellite. Should it be accurate to within a magnitude? Will this formula work for basically all satellites, including asymmetrical satellites such as the ISS? > > > Perhaps a better approach would be to assume that all > satellites are cylinders (since most of the brightest > satellites are rocket bodies) and compute the mean > reflected radiance (as a function of B) for all > orientations. The logical approach would be to throughly observe rocket bodies (near-perfect cylindrical objects) and create an equation(s) that would precisely mirror observations. Similar to curve-fitting. >Question for the list -- what do most > rocket bodies look like when viewing their ends? I am very certain that viewing the ends of rocket bodies results in a lower brightness than when viewing the "main body (for lack of a better term) ". I believe some one has said on this list that when a rocket body is tumbling, the dimmest part of the light curve happens when lookking at the ends of the cylinder. Thanks again! ------------------------------ Jonathan T. Wojack tlj18@juno.com 39.706d N 75.683d W 4 hours behind UT (-4) ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/tagj. ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www2.satellite.eu.org/seesat/seesatindex.html

**Next message:**Jonathan T Wojack: "Re: Morning Pass Of ISS"**Previous message:**Jonathan T Wojack: "Re: Morning Pass Of ISS/Venus"**Maybe in reply to:**Matson, Robert: "Satellite visual magnitude equations"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]

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