Afternoon John Im sending you by seperate mail a picture taken with an alt/az mount tracking as an equatorial mount that will work - Ive already done an astrometric solution on it with several astrometric programs so Ive given you all the relevant details with the jpg image sent to you. It is a bit unfortunate that the astrometric programs currently "readily" available cannot handle trailed stars as there are many instances where stars are trailed- eg tracking on an asteroid or comet which do not move at sidereal rate. One would have thought that after all these years such software would exist. I am aware of one program but it is not easily available - Im trying to get a copy of it at the moment. Unfortunately many of the video images will be time stamped and will cause the problem you had with Derek's image. This area of the frame will have to be blocked out in some way so the astrometric program does not see it - another problem is that I dont think everyone is using the same time stamp program which means there is no universal "block out' for all programs. I did try an idea I had late or rather early one morning. Take an image that has trailed stars and measure the X,Y coords of the satellite image and 3-8 bright stars trails - the end depending on whether the time of the image is start or end of frame. Then convert these X,Y readings to fit on (say ) a 640 x 480 grid.(Since not everyone has the same size image in terms of pixels along X,Y axis). Somehow or other plot these points on such a grid so you then have an image showing the location of the satellite and the 3-8 brightest stars appearing as dots. Maybe one could also measure the intensity of the pixels when determining the X,Y coords and plot the dots with a size depending on intensity. Now take this plotted image and put it in an astrometric program - I like PIXY because its freeware and do an astrometric solution. The 3-8 bright stars should enable a plate solution to be obtained and you can get the position of the satellite. In other words we are "converting the trailed images into point sources". I tried this in a BASIC program but couldnt solve the problem of how to save the screen display in BASIC as a file- BMP or PNG -- maybe someone reading this will be able to ? Maybe this will work or maybe it wont -- I dont know how the astrometric programs will respond to "seeing" this as a photograph? Just an idea.. Cheers Greg ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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