IDS Cookbook

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SUPPORT ASTRONOMER NOTES

Changing gratings

To change gratings on IDS you must type the following command on lpss7:
SYS> change_ids
This pops up the INT IDS change window. Click on Access grating port and answer 'yes' in the new window
Go to the telescope and take your old and new grating boxes
Open the grating box, open the three screws which fix the grating, and remove it
Mount the new grating with the labels in the correct position (this depends on the camera, check the labels under the grating door) and fix the screws
Close the grating door and come back to the telescope control room
Click the CLOSE botton and change the appropiate information on the grating box, click on Save Changes and Exit
Open the camera and the grating shutters:

SYS> gshut open
SYS> camshut open

Select the requested central wavelenght by typing:
SYS> cenwave 6000

Changing collimators

To change collimators on IDS you must type the following command on lpss7:
SYS> change_ids
Go to the telescope and take your old and new collimators boxes
Open the collimator box and open the three screw which fix the collimator
Take out the actual collimator in IDS
Mount the new collimator. There is just one permitted position for collimator.
Close the collimator door and come back to the telescope control room.
Click the OK botton and change the appropiate information on the collimator box
If necessary, open the camera shutter and the grating shutter:

SYS> gshut open

SYS> camshut open

Focusing the spectrograph

Mount a grating that gives well separated and well distributed lines on the CCD (e.g. R1200R)
Select an appropiate central wavelength (e.g. cenwave 7300)
Window the CCD so as to cover only the slit area. Recent window values are (20060613):
SYS> window 1 "[730:1230,1:4200]"
Take an arc to check counts and rotation
SYS> complamps CuNe+CuAr
SYS> arc 4 ``CuNe+CuAr''
In IRAF, type ing to initialise the ING package
Run ids_rotation to check the image rotation:
ing> ids_rotation r??????[1]
If necessary (rotation > 0.5 pixels), go into the dome and apply the recommended rotation offset
To correct from tilts, select three isolated spectral lines in your arc. Those lines should have good SN, not saturated, and be located in the upper, middle, and lower part of the CCD (but not too close to the edge, otherwise one or the other of the Hartmann shutters might cover some of them)
Put the collimator at the nominal position:
SYS> collimator 225
Take two exposures, one with the left hartmann shutter closed and one with the right Hartmann:

SYS> hart 1 0

SYS> arc 8 ``Hartman L''

SYS> hart 0 1

SYS> arc 8 ``Hartman R''
In the DRS, run the ids_tilt script:
ing> ids_tilt r345678[1] r345679[1] 177 559 978
Check that the computed pixels shifts are reasonable, otherwise the lines selection might have to be changed
Apply the recommended turns for A,B, and C capstan or the focus offset, or if only focus should be corrected then change only the collimator value, by typing e.g.
SYS> collimator 230 (note that the recommended collimator value should be between 215 and 240)
If all the pixels shifts are lower than 0.5 pixels, do not apply any capstan offset. Sometime there are errors in the capstan recommended values.
Repeat the above procedure until pixel shifts are lower than 0.5 pix in the nine positions
Do not forget to open both Hartmann shutters:
SYS> hart 0 0
Do not forget to update the web table with the micrometers positions for capstans A,B,C, and D (rotation).

Last Updated: 15 June 2006
Romano Corradi, rcorradi@ing.iac.es