User's Guide to the Nickel Spectrograph

Table of Contents

Hardware Overview
Aperture Wheel
Filter Wheel
CCD Stage
Detector Characteristics
Software Overview
CCD User Interface
Motor Controller
Observing Hints
Calibration Lamp Spectra

Data Archive
Mt. Hamilton Homepage

Motor Controller

The filter wheel, aperture wheel, collimating lens, grism tray, and CCD stage are controlled from the Motor Control user interface. This software is started automatically when the data-taking software is started (either from its icon or command nickel_spect_client). To start the motor control interface without starting the data-taking software, either click on the motor control icon or use the command nickel_inst_gui.

The motor control user interface is shared with the Nickel Direct Imaging Camera. All five motors are used with the spectrograph, but the items which apply only to the spectrograph are accordingly grayed out and set to their inactive state when the interface is used with the direct imaging camera.

The top bar of the GUI displays the status of the motors: Moving, Initializing, Done, or an error message. Below this, each motor has a corresponding row in the GUI; each; each line has five columns.

Column 1: Active
This column is a button which toggles the motor between active and inactive states, and displays its current state. To be moved, a motor must be in its enabled state (Active Yes). In spectrograph mode, all motors are are enabled on startup. You may toggle the states of these motors, and it is, in fact, recommended to place the CCD stage in an inactive state if you have tightened the locking screws on either side of the CCD stage to minimize flexure. Once a motor is set to inactive, it will be ignored by the controller.

Column 2: Item
This column displays the name of the motor.

Column 3: Ordinal Position
The filter and aperture wheels' positions are numbered 0-4 and 0-7 respectively. The Grating (grism slide) positions are numbered 0-3, while the CCD stage and Focus (collimator) do not have any ordinal positions. Column 3 either reports the motors' current or requested positions. If the Set Spectrograph and Initialize and Set Spectrograph buttons have gray backgrounds, columnn 3 reflects the current positions. If, however, those buttons have a yellow background (as in the illustration above), at least one of the entries in column 3 is a newly requested position, not yet made current. Clicking either button will cause the instrument to move to the requested position(s) (see description of these buttons below).

To move the filter wheel, aperture wheel, or grating slide to a new position, click on the current oridinal position for the device, and select from the pull-down menu thus invoked. (The pull-down menu may be "torn off" and kept as a separate window.) Click on the now-yellow Set Spectrograph or Initialize and Set Spectrograph to initiate the move.

Column 4: Raw Position
Column 4 shows the current positions of the filter wheel, aperture wheel, and grating (grism slide) in terms of stepper-motor counts. Columnn 4 should be regarded as "read only" for these three motors, i.e., you should see these numbers update as you move the motors, but should never have to change their values manually.

However, you do use Column 4 to move the CCD stage and Focus (collimator). Enter the desired position number into the entry box (being sure to hit Return). The Set Spectrograph and Initialize and Set Spectrograph buttons will turn yellow indicating that one or more motors have a newly requested position. Clicking either button will cause the instrument to move to the requested raw position(s) (see description of these buttons below).

Column 5: Name
Column 5 displays the name of the item (filter, aperture, or grating) corresponding to the ordinal position. Observers are responsible for insuring that the names reflect the currently installed filters and gratings (apertures may only be changed by staff members and we recommend having staff change gratings). Maintaining accurate naming in the motor control GUI is essential:
- The current names, along with raw and ordinal positions, are written to the FITS header of the data images.
- An observer may be misled if accurate naming has not been maintained.
Because of the potential for mistakes stemming from incorrect or out-of-date naming, all observers should check the contents of the filter wheel against the names in the motor control GUI on the first day of setup, updating the names as needed to correct mistakes and/or reflect their changes to the filterwheel contents.

Hg and Ne
The Hg and Ne buttons control line lamps for spectroscopic calibtarions. The Hg lamp takes a couple minutes to warm up, whereas the Ne lamp doesn't need any warmup time. Due to limited lifetimes and expense of replacing these lamps, please remember to turn them OFF when you are done using them.

Set Spectrograph and Initialize and Set Spectrograph
These buttons initiate motor moves. The Set Spectrograph button will make the move relative to the current position, whereas the Initialize and Set Spectrograph button forces the wheel to reread its zero-point fiducial, thus recalibrating itself before moving to the requested position. It is good practice to initialize before the beginning of each night's work, but is generally not necessary again for the remainder of the night, unless you have some reason to believe the wheels have lost track of their proper positions, such as will result from being moved by hand or having their power interrupted. (N.B. There is no harm in initializing as often as you wish, but it does cost a bit more time than a simple relative move).

This button quits the motor control GUI but leaves the wheel's positions unaffected.

Support Astronomers (
Last modified: Tue Jul 17 18:56:46 PDT 2012