if this is not the proper place for this post, please let me know ;)

i've been working on a tool to replace orbitel... orbitel has those old 64k memory limitations that we all grew up with and as such, when i use it to recombine all my TLEs into one file, the best i can hope for is about 3000 entries... not a good thing when i have over 12000 of them...

currently, my tool does in 10-20 seconds what orbitel takes upwards of 20-30 minutes to do (applying XRF and generating a new alltles file)... i plan on adding options to break out satellite groups from a master TLE list but right now, i'm more interested in another aspect...

i've been working with stellarium and as an avid sky watcher of the night, i'm always interested in that light floating over and what it is... i've never had much luck in the past with other tools that should be able to provide this information... sometimes it is little things like -xx degrees for west of GMT but the tool wants a positive number... then there's the limit on the number of TLEs that can be used and sorted thru... so, anyway, stellarium is an astronomy program that also has a satellite module so that it can show those birds flying over right now... my goal is to be able to sit outside with a program, stellarium for now, look at a light flying over and then look at stellarium and saying, "ok! that's some FC-Y1 debris flying there and flashing like that."...

so to help facilitate this and remove all the birds i won't ever see, i've (finally) figured out how to determine the apogee and perigee of a satellite's orbit from the TLE data (and a little geometry math that i found on the web. YAY!)... the satellites i compared my output with were right on target with the information provided by sites such as heavens-above... in other words, my code gave 1440kmx1459km for one bird and so did HA and other sites... sometimes there's a bit of a difference (50+KMs or larger) but for the most part, pretty close... the only thing i can see as being a deciding factor is the age of the TLE being used and how accurate it is for those couple of numbers used in this math...

so, with all that said, i'm trying to figure out the best way to filter out all satellites that one cannot hope to see with the naked Mark-I eyeball on any given night... at this point in time, i'm not worried about magnitude... only the furthest distance of a bird that we can easily see (guessing mag 4.5 or so if one really wants to go there)... this is where the perigee comes into play... i figure that if a satellite gets at least as close as XXkm on its pass by the earth, then we have a chance to see it (provided the pass is close to our location, too)... so, the question is what perigee is considered to be the top of the visual sighting range?

can we easily see satellites that are at 1000km (621miles)? what do you consider to be the top (in distance) of the visual sighting range?

at 1000km, my tool currently pulls over 7000 objects... some of these are on highly elliptical orbits... ok... we can't see them now but maybe in a few days or weeks when they come back close to earth on their next pass...