MODEL SGS
SELF-GUIDING SPECTROGRAPH

The Self-Guiding Spectrograph is designed to be used with an ST-7E camera. Although it can also be used with an ST-8E, there is no advantage in bandwidth when using the larger format camera.  The spectrometer and ST-7/8 are coupled and mounted as a unit onto the telescope (See Figure 1).  The system is quite handy for collecting spectra since both the object of interest and the spectrometer entrance slit are simultaneously imaged onto the tracking CCD, allowing the object to be viewed and accurately placed onto the slit.  The slit is backlit by an LED during the setup so it clearly shows on the tracking CCD.  Once the object is maneuvered onto the slit, self guiding will then hold the object on the slit.

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Identify Stellar Spectral Class

Spectrum of B Class Star

Spectrum of G Class Star

Spectrum of M Class Star

Figure 2 Sample Stellar Spectra

Measure Stellar Radial Velocities

Measure Emission Nebula

The spectra of M57 below was obtained using the low resolution grating and the narrow slit: 

Figure 4

Figure 5

The top image (Figure 4) is a screen shot showing the view of the tracking CCD displaying the slit and the object (M57) simultaneously.  The lower image (Figure 5) is a screen shot showing the view of the imaging CCD with emission lines from M57.

Measure Galactic Objects and Distinguish Quasars

The self-guiding feature of the ST-7/8 camera makes taking long exposures relatively painless and helps to keep the object centered on the slit for extended periods of time.   This technique is necessary if one attempts to measure the red shifts of galaxies of emission lines of quasars.  The samples below of M104 show the red shift of the galaxy relative to the star Mu UMA:

Figure 6 Screen shot of spectrum obtained of M104, The Sombrero Galaxy (The many small white spots are cosmic ray hits)

Figure 7 Graph showing the measured red shift of M104 relative to Mu UMA

Figure 8 Graph of emission lines in Quasar 3C273 obtained using an 8" SCT

Obtain High Resolution Spectra

Using the high resolution grating and the narrow slit the spectrograph is capable of resolving narrowly separated lines.  The sodium doublet lines in Figure 9 below are easily separated although they are only 6 angstroms apart.  The magnesium lines in the three stars shown in Figure 10 are separated by only 5.4 angstroms. 

Figure 9

Figure 10 Spectra of Several Bright Stars Captured with a Prototype SBIG Spectrometer on 2/3/98 Parameters:  Telescope:  10 inch LX200 F/6.3, Exposure:  120 seconds

Acquisition and Analysis Software Included

The spectrograph is provided with a special version of CCDOPS for data acquisition and SBIG's Spectral Calibration Program for analysis.  These programs make the spectrograph immediately useable as an analytical instrument without the need for the user to write or obtain third party software.

Figure 11 Screen shot of the Spectral Calibration Program supplied with the spectrograph

Optical Specifications

General Specifications

Figure 12 SBIG Spectrograph shown attached to an ST-7E

Revised: September 16, 2005 04:05:56 PM
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