Using the Spectrograph

Starting & Using the Spectrograph

1. Connect the CCD to the computer (head cable) and then to the power source. Make sure that the head cable is plugged into the computor downstairs through the parallel port (same as printer). Plug the power source into the wall (south outlet works best).
   
   
2. Remove eyepiece & adapter from telescope by unscrewing small knob on side. Connect the Spectrograph to the telescope. The flat side should be facing toward the center of the telescope's mount. Make sure the Spectrograph is securely mounted.
   
   
3. Open CCDOps on Planck (PC computor). The program should automatically link to the camera. If the link is found, a dialogue box will appear. If no link is found, go to the Misc menu and select Graphics/Comm Setup. Make sure the following parameters are correct: "Interface: Parallel" and "LTP Port: LTP 1." To bring up the dialog box, go to the Camera menu and select Setup.
   
   
4. In the dialogue box:
   
   • set temperature control to Active
   • set the temperature to ~40° C below the current temperature in the dome
   • set Resolution to Auto    (sets resolution low/medium for focus, and high for grab)
   • set Active CCD to Tracking
   • make sure Non-ABG Streak Rem. is set to No
   
   
5. Use the Focus mode (under the Camera menu) to focus and center your object on the slit. Make sure the LED on the bottom of the Spectrograph is on. You can adjust the contrast with the potentiometer. Set an exposure time agreeable with the sky conditions and the magnitude of the object (bright stars ~0.11 seconds) and set Frame Size to Planet. hit "ok." It is not necessary to take dark frames for centering an object, but it is for focusing.
   
   Estimated focus point values (on the telescope-control computer monitor)
         CCD+CFW : 3245
         CCD only : 2890
         eyepiece only : 2550
   
   
6. Take an image. Hopefully object is in the camera's field of view - if not, you can try moving the telescope slightly in some test direction (but at worst you can put the eyepiece back in, center on a star, and synch on it in TheSky). In between exposures in this mode, there is a delay that may be set (in seconds) in the focus box before hitting "ok." During this delay, look at the last downloaded image and adjust the focus using the handpaddle accordingly ("set" + "focus" = fast adjustments, "focus" alone = slow adjustments). You should be able to see the focus number changing on the telescope-control computer monitor. When the light is focused on the camera, the peak value that the camera reads should be at its highest, but its fluctuations are extremely sensitive, so first focus by `eyeballing it,' then fine tune it using the peak pixel value (located in the focus box on the screen when in focus mode).
   
   
7. You can also adjust the centering of the object in this mode by setting the telescope coordinates on the handpaddle.
   
   
8. Make sure your power level (bottom right display) is ~95% without going over 95%! Adjust temperature accordingly, in increments no larger than 5° C.
   
   
9. Once the object is centered and focused, go back to the Setup menu and make the Imaging CCD the active CCD and set binning mode to 4 and resolution to 1xN.
   
   
10. Under Camera go to Grab or use the self-guiding system to aquire your spectra. Note: make sure that the micrometer on the Spectrograph is set to the appropriate, approximate central wavelength and that the LED is OFF before aquiring spectra.
    
    
11. Take images (S/N=100, then pixel counts should be=10,000). To determine S/N, open up the image in CCDOps. Go to the Display menu and select Show Crosshairs. Put the cursor over the center of the object and click. A box will appear. Type "t" to change the box sixe. Try to make the box so it si just big enough to contain your object. Look in the crosshair display box, and remember the number listed for value. Then click on a piece of background sky and get the number listed for its value. S/N=square root of (object value - background sky value).
    
    
12. Save your images. (Set up a folder)
    
    
13. Remember to keep an eye on the power level!!!

Shutting Down & Storing the Spectrograph

1. Adjust the temperature to the ambient temperature! WAIT for the CCD camera to finish this controlled warm-up. This is very important!
   
   
2. Under "camera," quit the link.
   
   
3. Turn OFF the CPU! Detach cable and store properly. Carefully disconnect the Spectrograph from the telescope. Store properly in the CCD case. Slide the eyepiece back into the telescope eyepiece holder and firmly tighten the knob on the side.