Tony,
Find_Orb matches the MPC convention for the PA of the direction of motion in ephemerides, counting anticlockwise from North. The Positional uncertainty PA doesn't match the examples I tried counting clockwise or anticlockwise.
Here's a current example of the bright NEO 2014 VQ with cut-down ephemerides from the MPES and Find_Orb for my code J95, it's the " sig PA of 70 deg and 74 deg that I'm looking at:
K14V00Q [H=20.4]
Date UT R.A. (J2000) Decl. Sky Motion Uncertainty info
h m s "/min P.A. 3-sig/" P.A.
2014 11 11 020000 01 57 41.8 +33 13 25 8.96 155.8 2 355.4
2014 11 11 030000 01 57 59.4 +33 05 14 9.01 155.6 2 357.7
#Great Shefford
Date (UT) HH RA Dec '/hr PA " sig PA
---- -- -- -- ------------ ------------ ------ ------ ---- ---
2014 11 11 02 01 57 41.731 +33 13 26.15 8.96 155.8 0.2 70
2014 11 11 03 01 57 59.367 +33 05 14.86 9.01 155.6 0.2 74
Peter
---In find_orb@yahoogroups.com, <tony.evans@...> wrote :
I tried a couple of objects and it looks to me that MPC counts the PA anticlockwise from North and FO counts it clockwise. I never noticed that before!