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Bill-Gray / find_orb

Orbit determination from observations
https://www.projectpluto.com/find_orb.htm
GNU General Public License v2.0
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Does 'fo' support Lat+Lon input? #42

Closed void4 closed 1 year ago

void4 commented 1 year ago

I'd like to do ephemeris calculations from various locations on the globe to get the expected azimuth and altitude angles in case something like 2023 CX1 happens again :)

The fo usage site seems to document the -C flag to provide an observatory code. Observatories are not too densely scattered around the globe, however:

image

(Thank you for providing mpc_stat.txt, which allowed me to create this graphic, I've put it now as an interactive map up here: https://void4.github.io/obsmap.html)

Is it or would it be possible for ''fo' to accept custom lat/lon coordinates from the command line?

Bill-Gray commented 1 year ago

Sorry for the late reply! Actually, I fixed the problem fairly quickly (see commit a65e8e8cc5e951a20bebeff9bae0e929593d97fc); I was just really slow about posting here.

fo had several limitations in specifying coordinates, mostly dating back to when an "observatory code" was three or four characters, or (for some odd cases) seven or eight. Removing those restrictions means one can run, for example,

fo input_astrometry.txt -e/tmp/ephem/%c_%p.txt -C"n44.02_w69.9 s33.15_e127.89"

and have ephemerides generated for each object from the two (in the above case) lat/lon locations. I only specified two here, but you could keep going until your machine runs out of memory.

Note that I separated the n44.02 and w69.9 with an underscore, and similarly for the other location. Separate them with commas or a space, and fo will assume you meant separate codes called n44.02 and w69.9, and will correctly tell you they don't make any sense.

void4 commented 1 year ago

This is great! Thank you so much for your work, since what your program does might as well be magic to me :)

void4 commented 1 year ago

I've updated my code at https://github.com/void4/groundtrack that plots the map above and meteor groundtracks to use this new possibility, and it works, so I can close this issue now :)