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nsat / pypredict

Spire port of predict open-source tracking library
GNU General Public License v2.0
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gpredict values don't match pypredict for live observation #20

Closed rjobanp closed 9 years ago

rjobanp commented 9 years ago

The azimuth and elevation returned by pypredict.observe don't seem to be the same as those outputted by gpredict in the live view. The pypredict orbit number is also one more than gpredict. The latitude and longitude values do seem to match up.

I've checked a few different ground station/satellite combos and made sure the TLEs match; they all return the +1 orbit difference as well as different az/el numbers.

Below is a screenshot of a predict.observe output between SFGS and Lemur 1 and the gpredict screen at the same time:

image

Is this a bug or am I using pypredict.observe incorrectly? Thanks!

jtrutna commented 9 years ago

Oooh, a bug! I'll check it out! Do you have the QTH and TLE database files you're using?

rjobanp commented 9 years ago

The TLE was tle = predict.tle(40044) and the qth was the SFGS lat/lon/altitude ('37.7727', '-122.4070', 25) On gpredict it was the same thing, the TLE was pulled from our tle service http://tle.nanosatisfi.com/40044 and the ground station was put in with those lat/lon/alt values.

rjobanp commented 9 years ago

Turns out I was using East Longitude! Pypredict takes West Longitude values for QTH. Thanks for the info on that.