by rising it up by ~25 cm. All the operations were performed keeping the clean air flow in position 2 (high flow).
The actions were performed considering the reference position provided by marionette OL, once the F7/PAY had been realigned using the green laser injected from N.
The main actions are listed below.
- Check of F7 monitor zeroes and mechanical readjustment of the vertical reference set point
- F7 horizontal reference rotated by ~15 mad CW accomplishing ~11 mard recovering of the horizontal arisen the day before using the green laser
- F7 body vertical stops on the bottom have been fixed to ~7 mm
- The separating roof was closed.
- The shapes of the weights loading the F7 body, just above the actuation cage, have been fixed and suitably screwed in order to balance the F7
while checking the payload actuators centring
- The payload stops into the actuation cage were finally adjusted to ~ 5 mm
- The disk with the laser diode was mounted on the SNEB flange, with the position of the departing beam adjusted to y = -1.6 mm (towards west), z = -2.4 mm (down) with respect to the center of the disk.
- This beam was aligned to a point on the NE flange at coordinates y = +2.7 mm (towards east), z = +4.0 mm (up) with respect to the center of the disk.
- After removing the screen on the NE flange, the beam was reflected off the NE mirror back towards the SNEB flange. The NE mirror should be in its nominal position when the reflected spot falls 20.15 mm below its departing point, so at y = -1.6 mm (towards west), z = -22.55 mm (down).
- Initially, the reflected spot was off by about 20 cm towards west, see fig 1. This corresponds to a mis-alignment of a bit more than 10 mrad in ty, which is similar to what was seen for previous payloads. This has already been corrected by making adjustments to the payload.
- Increasing the laser power a bit, two additional ghost beams can be seen above and below the main reflection. The lower one is a bit brighter, this is probably the direct reflection of the AR coating, while the weaker upper one is likely a triple reflection (HR-AR-HR), see fig 2. The fact that the stronger one is below suggests that the wedge has it thinnest part pointing down. The spots are separated by about 22 mm, which is consistent with the wedge of the mirror substrate of 1070 urad. The reflections from the AR coating are not perfectly above and below the main reflection of the HR coating, suggesting that the wedge might be rotated by about 7 degrees around tz. Note that these measurements were not very accurate, since the payload was still uncontrolled at the moment the picture was taken.
- Two overlapping spots can be seen about 75 cm to the east of the SNEB flange, see fig 1 and 3. These are not moving with the mirror, so they should be the reflections of the viewport. This is consistent with an intended tilt of about 4 degrees and no wedge.
We removed two cameras that were mounted on the pre-alignment jig of the NE tower that were used to monitor the anchors. We also noted that by switching off the IP cameras, the tower was absolutely dark. These cameras were probably illuminating the payload with an IR LED.