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Mounting filters when using ALFOSC

  • Filters are mounted either in ALFOSC or FASU (Filter And Shutter Unit). Narrow band filters should always be mounted in FASU.
  • Start the ALFOSC UIF
  • Move the filter wheel to the position opposite to the one you want to exchange.
  • Take the filter from the carousel, use optical paper when handling the filters.
  • Check the filter's general appearance for scratches, dust, etc. Ask Tapio pursimo to update the filter status table if necessary.
  • If needed check staff instructions for cleaning filter.
  • Take the ALFOSC filter frame from the filter carousel and put the filter into it.
  • Go to the dome floor and open the access box.
  • Loosen the 3 screws in the holder.
  • Carefully remove the filter and wrap it with optical paper.
  • In ALFOSC the filters should be mounted the reflecting side towards sky.
  • Tighten the 3 screws in the holder.
  • Put the removed filter back to it's correct drawer in the filter carousel.
  • Update the ALFOSC filter wheel setup using the GUI editor in the following way:

    1. Log in to 'tessa' as user 'obs'.
    2. Run the command 'editsetup'.
    3. Make the changes needed.

  • Press 'Read Setup' on the UIF.

Mounting filters in FASU

  • FASU has two filter wheels A and B, latter being the uppermost.
  • Take the filter from the carousel, use optical paper when handling the filter.
  • For 51 mm square filters there are special protection rings that should be used.
  • For relatively thick filters the metal ring holding down the filter can stick out above the filter holder. Such filter should only be installed in filter wheel B. (If you put them in the FASU A, the wheel can get stuck and/or the filter can fall out of the wheel!!!)
  • There are a set of plastic rings to be used together with the 95mm round filterholders for FASU in order to mount ING TAURUS filters, which are 76mm round and about 14 mm thick. At most 4 such filters can be mounted at the same time. The set of rings is found in the drawer "FASU rings". Mount such that the filter protrudes in the upward direction when viewing the filterholder the way it is mounted in FASU, and mount them only in FASU B.
  • Check the filter's general appearance for scratches, dust, etc. Ask Tapio Pursimo to update the filter status table if necessary.
  • If needed check staff instructions for cleaning filters.
  • Filter frames for FASU filters can be found from rectangular box. Take the propers sized frame and label it with the filter name you put in there.
  • Put the filter into the filter frame using the FASU filter tools found on the desk next to filter carousel.
  • Go to the dome floor. To reach each of the wheels one needs to unscrew four bolts on side of FASU holding the metal plate. With UP and DOWN buttons that are next to the plate one can change the filter position. In order to move the wheel with half a step one needs the change the switch from 'local' to 'remote' on top of FASU handset.
  • When the filter to be removed is in available raise the lever on the left and pull it towards you. Now you can take the filter with the frame away from the wheel.
  • Carefully remove the filter and wrap it with optical paper.
  • In FASU the filters should be the reflecting side towards sky.
  • The square holders should be oriented according to the mark on the rim of the holder and the centre of the slot i.e. rotated by 15 degrees in the wheel.
  • Put the metal plate back. Tighten the screws.
  • Put the switch back to 'local' and open the shutter.
  • Put the removed filter back to it's correct drawer in the filter carousel.
  • Update the FASUA or FASUB setup definition file using the GUI editor in the following way:

    1. Log in to 'tessa' as user 'obs'.
    2. Run the command 'editsetup'.
    3. Make the changes to the FASU wheels that are needed.

Mounting filters when using MOSCA

  • Filters are mounted in the FASU Unit. Follow the instructions above.

Mounting filters when using NOTCAM

  • NOTCam is an infrared instrument and the whole instrument is inside a huge croystat cooled to about -200 degrees C. For this reason changes in the setup, like installation of filters, is made only while the instrument is warm and open in the clean room of the Service Building, hopefully about once per year in the future.
  • Instructions for installation of NOTCam filters..

Mounting filters when using StanCam

    If you haven't seen the filter cassette before have a look at the top shelf of the wooden cupboard in the control room. You should see the "StanCam filter mechanism align tool", which is similar to the cassette in use.

    Before changing filters:

  • The filters BVR and clear#126 are to be used for FIES target acquisition. So it would be nice if we could not swap them ever. And if they are swapped it would be nice if they go back to positions 2,3,4,8 respectively. This because documentation and scripts expect these filters to be at those positions.

    At the Electronics room:

  • Choose an appropriate filter holder from the wooden briefcase (labelled "StanCam filter holders 60mm/51mm sq").
  • label the holder
  • carefully mount the filter in the holder.
  • blow dust away from the filter

    At the observing floor:

  • open the cassette door (right from the dewar), unscrew the bolt and carefully pull the cassette out. Be careful, because the left hand side of the cassette is open and there is no mechanism to keep the filter holders in the cassette.
  • Put the cassette on the floor
  • Change the filters in the cassette. Check the orientation of the holder and check that the reflecting side is towards sky.
  • Push the cassette back in it's place, tighten the screw and close the cassette door

    At the control room:

  • At the TCS edit the filter name file:
    e.g. Name-CCD-filter i13_int_793_170
 

 

Back to top Last modified: 22-Mar-2012