Björn Gimle wrote: >> >> Method: Canon Digital Ixus 400 + ASTRORECORD astrometric software. >> Camera at manual mode, "10 second" (= 10.7 second) exposure, wide field >> f2.8/7.41 mm. >> > Does this software consider "wide" angle pillow distortion? ASTRORECORD uses the Turner method and considers the common distortions of a wide field lens. It originally was designed for professional quality reduction of "small camera" (35 mm analogue SLR) meteor multistation photographs for orbital determinations. Results on meteor trajectories and orbits obtained using this software have been published in several peer-reviewed papers. These meteor images are taken typically with an analogue 35 mm SLR with 35-50 mm lens, hence "wide" angle. The images of my digital camera are equivalent to a 43 mm lens on an analogue SLR, so comparable (the field width is some 50 degrees). > How many star positions do you, Marco, use in one reduction? Typically some 100 stars. Good results actually can be obtained with much less reference stars. Important is that they spread well around the trail. > How far from the satellite position? I use stars spread over the whole image, taking care to make sure the trail is totally surrounded. I als try to have the immedate vicinity of the trail well covered. > Have you verified the accuracy by taking different stars? The software calculates and gives feedback on the deviations in the average positions measured from star to star. With my camera setup, the internal accuracy of measured star positions is typically given as 25" to 30" provided enough stars are measured. The accuracy of the satellite positions is less than this, as this is also influenced by the timing error, and how well the trail shows up on the image (how well the trail ends can be determined). There are some tests of accuracy relative to other stations, and a test where positions obtained on ISS are compared to an ISS TLE, on my website: http://home.wanadoo.nl/marco.langbroek/satcam.html This also discusses some pittfals encountered. > I have only tried software that assumes flat-field, narrow (CCD) images. AstroRecord was specifically designed for wide field images with field sizes of several tens of degrees, see above. It does not assume flat-field. The whole setup here is an experiment, to see whether it works for (bright) satellites. After a month of operation, is seems it does work, bar a few pittfals. Feedback is welcome, as I strive to continuously improve. - Marco :-) ----- Dr Marco Langbroek - SatTrackCam Leiden, Cospar 4352 Leiden, the Netherlands, 52.15894 N, 4.48883 E (WGS84), +5 m ASL SatTrackCam: http://home.wanadoo.nl/marco.langbroek/satcam.html Station (b)log: http://sattrackcam.blogspot.com e-mail: meteorites@dmsweb.org ----- ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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