European Southern Observatory New Technology Telescope

General :
Observations :
Operations :

EMMI - DIMD Focus Flexure Monitoring

The purpose of this procedure is to monitor the mechanical flexures produced  into EMMI - DIMD with the rotator at different angles measuring the shifts of image on CCD in x,y and focus.

The procedure takes n red exposures of a 1"x3.2" slit  seen through Focus Wedge , changing the rotaror angle by a rotator step editable in the DimdFocusFlexure.obd, then, measures the displacement of the image on the CCD in x and y directions for the leftmost image and dy ( defocussing)  for the rightmost image
( x axis is along the dispersion and y axis is across the dispersion ).

The procedure takes n blue exposures of a 1"x3.2" slit  , changing the rotaror angle by a rotator step editable in the DimdFocusFlexure.obd, then, measures the displacement of the image on the CCD in x and y directions
( x axis is along the dispersion and y axis is across the dispersion ).
 

To control rotator from wemmi , the DimdFocusFlexure.seq script must simulate  telescope presets .
 Therefore, when starting the template,

• the telescope must be in standby mode,
• no interlock may be activated
• but hydraulics pressure may be low .

It will also restore the previous status of all telescope LCU's after completion or after a foreseen error .

If the template is aborted manually or a due to a non-foreseen error, it may be necessary to restore the telescope status manually :
in particular, to restart the template after such a case,  it may be necessary to STOP TCS from the control panel.

Procedure:

Load DimdFocusFlexure.obd in BOB :

Update grating names and, if you wish,  the rotator step angle :

 Check that rotator may rotate safely :

  it is advised to keep light on in EMMI room and switch camera video watching to EMMI .

Check that

• no interlock is on
• M3 is looking side B
• telescope is in standby

 Start template in BOB

After first exposure, in MIDAS/PCO display window, adjust boxsize to about images

separation, click left then right image, then click twice mouse middle button
for red and click image, then click twice mouse middle button for  blue.

check that rotator is moving from -180 degreed to 180 degrees and back, stepwise.

At completion pick up 3 printouts  and store them into maintenance result binder.

Compare to previous  results and report any significant variation .

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