C.12 From Revolution 191

1. The transition from band 1 to band 2 moved from 4.05 $\mu$m (Bracket-$\alpha$) to 4.08 $\mu$m. This significantly improved measurements of Bracket-$\alpha$.
2. Dark-current measurements now follow all grating scans Previously only the dark measurement preceding a grating scan was guaranteed to be performed. This was a significant improvement, especially in AOTs 1 and 6.
3. Photometric checks delayed, to prevent detector memory effects from these measurements. This gave somewhat better data in some cases.
4. Velocity correction for FP measurements amended, giving better centring of AOT 7 line observations, but no effect on data interpretation.
5. Improved precision in the FP calibration tables, giving significantly better tracking between grating and FP.
6. Switch to spectral order 4 in FP measurements below 12.2 $\mu$m. The effect of this was to give better grating resolution and less leakage.
7. Grating tracking introduced also for the shortest FP scans, significantly improved tracking for short scans.