Space station flyovers

4 those of U still with jobs/current Calif* residents, have some flyovers.

Wed Jul 22/09:27 PM 12 above N 11 above ENE
Sat Jul 25/09:07 PM 29 above NNW 14 above ESE
Sun Jul 26/09:31 PM 27 above W 20 above SSE
Tue Jul 28/08:46 PM 36 above SW 10 above SSE


Rise of the gyro compasses

U need to determine true North. U make lots of magnetic fields. Wind makes GPS heading unreliable. U need to fly for hours & hours. U need a gyrocompass. Gyrocompasses sense the rotation of the Earth to determine true North. In an IMU, the rotation shows up as a 90' rotation over 6 hours. That's right. If U left a super accurate IMU on a table for 6 hours & it was calibrated for true 0 rate, it would show a 90' turn. It can use this rotation to correct the heading over many hours.

By default, the 0 rate on a typical ADXRS610 is always calibrated 0.00004V off because of the Earth's rotation.