[amsat-bb] Re: Satellite Orbit Prediction in Python
juicewvu at gmail.com
Mon Sep 28 15:12:18 PDT 2009
Thanks for the link especially to the source as I am very interested
in implementing something very similar. (for my QTH of course)
email/jabber: juicewvu at gmail.com
On Mon, Sep 28, 2009 at 2:41 PM, Bryan Klofas <bklofas at gmail.com> wrote:
> Hey Mark--
> We also use pyephem for web-based pass times calculations at Cal Poly.
> Source is here, but it was written a few years back, and uses the older
> (now depreciated) ephem.Body attributes. It also sometimes has trouble
> with the formatting on the webpage, although that may be a firefox bug,
> I'm not sure.
> Bryan Klofas, KF6ZEO
> Mark VandeWettering wrote:
>> I just thought I'd drop a quick note here about some fun I've been
>> having today with satellite orbit prediction in Python. When I
>> started mucking around with satellites, I used "predict", which was
>> pretty good, but at some point I wanted to answer some questions which
>> weren't easy to answer using predict. Questions like "when will
>> AO-51 be visible from both my home in CM87 and locations in Hawaii",
>> or "what was the radius of the circle of visibility for AO-7 compared
>> to ISS"?
>> Luckily, I'm a programmer. In fact, I'm a programmer who programs
>> for fun. So, I did a bit of research, and then coded up a version of
>> G3RUH's "Plan 13" algorithm in Python, and then wrote some scripts to
>> download elements from celestrak, and then a simple one to print data
>> on the next pass of any named satellite. And, they worked pretty
>> good. I've used them for the last year or so to do all my pass
>> predictions. But there are still a couple of minor issues with the
>> library. It didn't handle geosynchronous satellites very well. It
>> implemented only the most basic of orbital models. I was never
>> confident that the "is this satellite in eclipse" stuff working
>> exactly right.
>> Luckily though, it turns out that someone else has been busy writing a
>> more complete library: PyEphem http://rhodesmill.org/pyephem/
>> It's a library whose primary purpose is to calculate the positions of
>> astronomical objects. I've used it a couple of times to (for
>> instance) figure out the size of Mars compared to Jupiter, and found
>> it very easy to use. But today, I realized that it had a full
>> implementation of the SGP4 and SDP4 orbital models built in, and could
>> be used to predict satellite passes. As a proof of concept, I
>> hacked together a 23 line script that could print the details of
>> upcoming ISS passes. It seems to work great, and is really quite
>> easy to use.
>> You can find some of the simple example code at my blog:
>> I'll probably be porting all of my existing scripts to use this soon.
>> In the mean time, if you have a similar task, you might look to it to
>> solve your custom satellite prediction problems.
>> 73 Mark K6HX
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