Position Ephemeris

[bigmasterdrago]

When trying to determine when closest approach happens, normally we assume when brightest. This is not necessarily so due to changes in phase angle etc. Since my column Re is only showing AU = 0.00, I cannot really figure out when that happens. in the ephemeris since it has not switched to kilometers. Looks to be ~Apr 8, 19:30UT based on Horizons and others. I used the just downloaded the MPC NEA Today els. The position tomorrow (Apr 8) at 15:00cdt shows 22h38m23.9s +32d54'01s in ST4. This should closely jive with that of Horizons (Apr 8, 22:00UT) 22 39 33.13 +32 29 47.7. Position difference is ~1/2 degree away. I've checked over the location lat and long, times, etc and cannot discover the dependency. Please help.