3.3 History of AOT Changes throughout the Mission

The following lists -- per revolution number, i.e. chronologically -- the changes made to the AOT logic during the mission.

From revolution 49 (in the Performance-Verification phase)

1. New responsivities, taken from Saturn observations and SCP checkout observations, in the uplink tables.
2. Improved wavelength accuracy in the uplink tables.
3. The maximum commandable grating position increased from 3700 to 3740 as a result of performing the grating limits test in revolution 8.
4. The bias levels for the detectors were lowered by 1 (see Table  2.4). For LW2 the bias level was lowered by 2. The default HOLD mode sampling was set to 0.5s ramps.
5. 4, 2 and 1 s ramps were not used any more (Grating AOTs). 1 s ramps were still available for use in FP observations.

From revolution 55

• The optimum offsets were set for the FPS parallelisation as determined from 2nd order data in revolutions 35 and 47. For FPL approximate offsets were given, based on results for first order measurements from revolutions 31 and 35.

From revolution 61

1. The maximum commandable grating position decreased from 3740 to 3700 as a result of performing tests of further data from grating scans.
2. Improved FP wavelength accuracy in the uplink tables.

From revolution 69

1. New responsivities, taken from Pallas observations, in the uplink tables.
2. New detector dark current, taken from Peter Clegg, in the uplink tables.
3. New power and noise levels, calculated by Matt Griffin, in the uplink tables. The NEPs were changed correspondingly.
4. Improved FPS wavelength accuracy in the uplink tables. FP scan range: 46.795-197.049m.

From revolution 90

1. New noise levels, recalculated by Matt Griffin, in the uplink tables. The NEPs were changed correspondingly.
2. Mini-scan overlap increased to 5 spectral elements, Overlap between FPs raised to 1.8m.
3. Maximum wavelength changed to 196.974m.
4. 1 s ramps were not used any more in FP AOTs. So only 1/4 and 1/2 second ramps were allowed. The usage of 1/4 second ramps was inhibited for source strengths below 10000Jy.

From revolution 100

• Closed flashes, which are needed for dark current subtraction and absolute response correction, were used instead of open illuminator flashes.

From revolution 150

1. FPS cut-off changed to 70m.
2. Update of Cal-U file L-FPSCAN: Start and end FP offsets added for each microscan.

From revolution 191

1. Implementation of the new values for the responsivities of the SW1, SW2 and LW5 detectors.
2. Implementation of the new transmission profiles generated from Ceres and NGC 7027.
3. New detector dark current, taken from illuminator flashes, in the uplink tables.
4. Detector bias levels were set to (4, 4, 3, 3, 3, 3, 2, 3, 3, 2) for the sequence of detectors SW1-SW5 and LW1-LW5 (for the voltage values corresponding to these levels see Table  2.4)
5. New power and noise levels, recalculated by Matt Griffin, in the uplink tables.
6. Improved wavelength accuracy in the uplink tables.
7. L-FPSCAN: Correction of the wrong values of the offsets for the FPS microscan corresponding to the 93.225-93.616 interval plus change in the cut-off wavelength between FPS and FPL.
8. Maximum wavelength changed to 196.989m.
9. Wrong interpolation in LWS FPL offsets corrected.

From revolution 237

1. Use of LWS serendipitous/parallel mode; the HOLD mode was set to use 1 s ramps so that the LWS parallel mode can operate correctly.
2. Changes to ensure a constant detector temperature throughout a revolution.

From revolution 277

1. L-FPSCAN: implementation of new micro scans lengths, with a maximum FPL offset change of 5 between two steps.
2. L-OPTIC: Correction of the wrong values of the grating mode relative transmission efficiency.
3. L-SETNGS: Increase of the scan width for the L04 AOTs (2 resolution elements added for both FPS & FPL).

From revolution 336

1. Illuminator flashes avoided during the middle of an observation.
2. Improved wavelength accuracy in the uplink tables for grating and FPL.

From revolution 411

1. New LWS illuminator flash scheme (Change ILL1LEVEL1 ... ILL5LEVEL2 to 180).
2. An increase of the time required to make the wheel movements.
3. The 1st illuminator flash leaves the wheel in the grating positions and now the 2nd illuminator flash must leave it in the opaque position.
4. Use of the FPL for the opaque configuration of grating AOTs.
5. LWS parallel mode stopped.

From revolution 526

• LWS parallel mode restored.

From revolution 584

• Improved wavelength accuracy in the uplink tables for revolution 349 onwards. This resulted in re-derived FP coefficients.

From revolution 764

• LWS parallel mode now also after 2nd illuminator flash of Ground Station Handover.