The light entering the telescope can be (fairly) easily directed to either the Imager, the Spectrograph (connected to the old imager), or the Eyepiece Holder. See the Cameras page for their locations.
| Light that enters the Guide Aquire Module (the GAM), if allowed to pass straight through, will end up at the imaging camera, after having passed through whatever filter is in position (M3 on the TCS) in the main 2" filter wheel. There is a "tertiary mirror" that resides on a movable stage within the GAM. This mirror can be moved into the light path (just above where the imaging camera sits), and rotated so that the light will be reflected out the sides of the GAM (N, S, E or W ports). See image at right. |
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On the East side of the GAM, just above and behind the spectrograph, there is a crank that will move the tertiary stage (see image at right).
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CAUTION: THE READING ON THE GAM "Y" POSITION FOR THE MOVABLE PICKOFF MIRROR MUST, MUST BE ABOVE +890, OR IT WILL CRASH INTO THE TERTIARY MIRROR!!!!
On the North side of the GAM, there is a single LED that, when lit, indicates that the tertiary mirror is in the light path (see this image).
While the teriary mirror is in the light path (which it needs to be to look through the eyepieces or use the spectrograph), it can be rotated using the TCS Console as follows: