CORRECTING THE MECHANICAL POSITIONING OF THE WHEELS
From time to time the position and tilt of the slit, grism and pupil wheels should be
measured more precisely, especially when mechanical interventions in
the entrance wheel have taken place.
WARNING: the following procedures are relatively risky and should be attempted by experts only. Feel encouraged to seek help from the duty engineer or instrument specialist)
In case the slit is tilted with respect
to the detector columns the wheel has to be rotated until properly aligned using epics:
- Check that the telescope is pointing to zenith.
- Check that the primary mirror petals are open.
- Check that the tertiary mirror is out (i.e. light to CASS focus), specially after a GLAS run.
- Switch all dome lamps off EXCEPT the dome weak flat lamp (four switches down); set it at full intensity (dial).
- Check that the agmirror is out. If not:
SYS> agmirror out
- Take an image of the problematic slit (with l0p75 in our example):
SYS> limage hc
SYS> lslit l0p75
SYS> glance liris 3
- Start epics:
SYS> start_epics
In the new window, clic on "LIRIS", then clic on "slit wheel", then clic on "motor". A new window shows up. Write down the VAL value.
- Check the image and, introduce some small value (~0.05) in the box next to TWV, press return and then click on TWF (to move slit down) or TWR (check the entrance wheel in this diagram for direction). Then:
SYS> glance liris 3
and iterate until you get a nice alignment. Then write down the new VAL value.
The VARIATION ANGLE (same as the variation value requested in the following step) will be the new VAL minus the old VAL.
- Make and cd into a new directory following the date, such as
SYS> mkdir /home/whtobs/liris/slits20080610
SYS> cd /home/whtobs/liris/slits20080610
- Get the present position of the slit wheels:
SYS> lbuild_mch_hometables lslit_config.dat lslit_distance.dat -home1 lslit_home1.dat.old -home2 lslit_home2.dat.old -dir /wht/etc/
- Modify it with the new values (in the directory you just created):
SYS> lbuild_mch_hometables lslit_config.dat lslit_distance.dat -home1 lslit_home1.dat -home2 lslit_home2.dat -distf lslit_distance.dat -chpos -dir /wht/etc/
It will ask you the position to change (0=quit): Look at taurus:/wht/var/lslit_home1.dat to check which line number corresponds to the problematic slit. The line number will be the position to change.
Now it will ask you to introduce the variation value: Type the value you previously calculated.
Finally type 0 to quit the script.
NOTE: If, instead, you want to change the position of the home mark (therefore changing EVERY slit by the same amount), type -1 when asked about the position to change (0=quit).
- Now, copy the files to where they belong and load the new configuration:
SYS> cp lslit_home1.dat /wht/var/
SYS> cp lslit_home2.dat /wht/var/
SYS> lloadconfig slit
Log in to taurus as lirissm
SYS> ssh taurus -l lirissm
Set the current directory
SYS> cd /wht/etc/liris
Rename the old file
SYS> mv lslit_distance.dat lslit_distance_pre_yyyymmdd.dat
copy new version
SYS> cp /home/whtobs/liris/slitsyyyymmdd/lslit_distance.dat .
Note that to be sure the file is loaded correctly one should reboot the LIRIS IOC VME crate out on the telescope (press reset button on the CPU card).
In case the spectra are tilted with respect
to the detector columns the grism wheel has to be rotated until alignment using epics:
- Turn the Ar (or Xe) lamp on:
SYS> llampon 1
- take some arc in the problematic grism (e.g. lr_zj), with:
SYS> agcomp
SYS> lspec lr_zj l0p75
SYS> glance liris 3
- Start epics:
SYS> start_epics
In the new window, clic on "LIRIS", then clic on "grism wheel", then clic on "motor". A new window shows up. Write down the VAL value.
- Check the image and, introduce some small value (~0.05) in the box next to TWV, press return and then click on TWF or TWR (check this diagram for directions).
SYS> glance liris 3
and iterate until you get a nice alignment. Then write down the new VAL value.
The VARIATION ANGLE will be the new VAL minus the old VAL.
- Make and cd into a new directory following the date, such as
SYS> mkdir /home/whtobs/liris/grisms20080610
SYS> cd /home/whtobs/liris/grisms20080610
- Get the present position of the grism wheels:
SYS> lbuild_mch_hometables lgrism_config.dat lgrism_distance.dat -home1 lgrism_home1.dat.old -home2 lgrism_home2.dat.old -dir /wht/etc/
- Modify it with the new values (in the working directory):
SYS> lbuild_mch_hometables lgrism_config.dat lgrism_distance.dat -home1 lgrism_home1.dat -home2 lgrism_home2.dat -distf lgrism_distance.dat -chpos -dir /wht/etc/
It will ask you the position to change (0=quit): Look at taurus:/wht/var/lgrism_home1.dat to check which line number corresponds to the problematic grism. The line number will be the position to change.
Now it will ask you to introduce the variation value: Type the VAL you previously calculated.
Finally type 0 to quit the script.
NOTE: If, instead, you want to change the position of the home mark (therefore changing EVERY grism by the same amount), type -1 when asked about the position to change (0=quit).
- Now, copy the files to where they belong and load the new configuration:
SYS> cp lgrism_home1.dat /wht/var/
SYS> cp lgrism_home2.dat /wht/var/
SYS> lloadconfig grism
Log in to taurus as lirissm
SYS> ssh taurus -l lirissm
Set the current directory
SYS> cd /wht/etc/liris
Rename the old file
SYS> mv lgrism_distance.dat lgrism_distance_pre_yyyymmdd.dat
copy new version
SYS> cp /home/whtobs/liris/grismsyyyymmdd/lgrism_distance.dat .
Note that to be sure the file is loaded correctly one should reboot the LIRIS IOC VME crate out on the telescope (press reset button on the CPU card).
From time to time, the alignment of every pupil stop should be checked:
- Check that the telescope is pointing to zenith.
- Check that the primary mirror petals are open.
- Check that the tertiary mirror is out (i.e. light to CASS focus), specially after a GLAS run.
- Switch all dome lamps off EXCEPT the dome weak flat lamp (three switches down); set it at 50% intensity (dial).
- Set the camera to reimaging mode in h filter and pupil for K band:
SYS> limage h
SYS> lcamera reimaging
SYS> lpupil pcblnkxl
SYS> agmirror out
- Take an image:
SYS> glance liris 1
Take a look at the image. You should see an image (like this one) of the primary mirror+the shadow of both the secondary and its spider+the shadow of the K pupil (a round spot in the centre plus 3 legs). If it is well centered (that is, if the pupil is correctly masking the shadow of the secondary mirror), then you are finished (do a " SYS> lcamera camerain " to go back to observing mode).
- If there is some misalignment, then start epics (WARNING: the following procedure is relatively risky and should be attempted by experts only. Feel encouraged to seek the help from the duty engineer or instrument specialist) :
SYS> start_epics
In the new window, clic on "LIRIS", then clic on "pupil wheel", then clic on "motor". A new window shows up. Write down the VAL value.
- Introduce some small value (~0.05) in the box next to TWV, press return and then click on TWF or TWR (check this diagram).
Then reimage the pupil with " SYS> glance liris 1 ", and iterate until you get a nice alignment. Then write down the new VAL value.
The VARIATION ANGLE will be the new VAL minus the old VAL.
- Make and cd into a new directory following the date, such as
SYS> mkdir /home/whtobs/liris/pupils20080610
SYS> cd /home/whtobs/liris/pupils20080610
- Get the present position of the pupil wheels:
SYS> lbuild_mch_hometables lpupil_config.dat lpupil_distance.dat -home1 lpupil_home1.dat.old -home2 lpupil_home2.dat.old -dir /wht/etc/
- Modify it with the new values (in the working directory):
SYS> lbuild_mch_hometables lpupil_config.dat lpupil_distance.dat -home1 lpupil_home1.dat -home2 lpupil_home2.dat -distf lpupil_distance.dat -chpos -dir /wht/etc/
It will ask you the position to change (0=quit): Look at taurus:/wht/var/lpupil_home1.dat to check which line number corresponds to the problematic pupil. The line number will be the position to change.
Now it will ask you to introduce the variation value: Type the VAL you previously calculated.
Finally type 0 to quit the script.
NOTE: If, instead, you want to change the position of the home mark (therefore changing EVERY pupil by the same amount), type -1 when asked about the position to change (0=quit).
- Now, copy the files to where they belong and load the new configuration:
SYS> cp lpupil_home1.dat /wht/var/
SYS> cp lpupil_home2.dat /wht/var/
SYS> lloadconfig pupil
Log in to taurus as lirissm
SYS> ssh taurus -l lirissm
Set the current directory
SYS> cd /wht/etc/liris
Rename the old file
SYS> mv lpupil_distance.dat lpupil_distance_pre_yyyymmdd.dat
copy new version
SYS> cp /home/whtobs/liris/pupilsyyyymmdd/lpupil_distance.dat .
Note that to be sure the file is loaded correctly one should reboot the LIRIS IOC VME crate out on the telescope (press reset button on the CPU card).
- Now, check that it works, by selecting some other pupil such as e.g. pcblnk:
SYS> lpupil pcblnk
and imaging it, and finally go back to camera configuration with:
SYS> lcamera camerain
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