User manual SBIG STV

[. . . ] PRICE $10. 00 Operating Manual STV Video Camera and Autoguider Santa Barbara Instrument Group 147-A Castilian Drive Santa Barbara, CA 93117 Phone (805) 571-7244 Fax (805) 571-1147 sbig@sbig. com www. sbig. com Santa Barbara Instrument Group 147-A Castilian Drive Santa Barbara, CA 93117 PHONE (805) 571-7244 FAX (805) 571-1147 Note: This equipment has been tested and found to comply with the limits for a Class B digital device pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses, and can radiate radio frequency energy and if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. [. . . ] See Appendix C, page 49, for details. When the graphic information is on the video screen you can toggle on the 3 dimensional graph of the star profile by hitting the Value button again. As the graph is updating, the alphanumeric display provides the quantitative data: OPTICAL QLTY. Exp=50ms FWHM= 2. 6^s Strehl= 72% In this example the STV is using an exposure time of 50 milliseconds, the FWHM (Full Width Half Maximum) of the star image is 2. 6 arcseconds and the Strehl ratio of the optical system compared to a theoretically perfect system is 72% (Reminder: You must accurately set your telescope's focal length and aperture diameter in the Setup Menu before using this function) . For an explanation of the theory and calculations behind the Optical Quality Monitor mode see Appendix C, page 49. 23 Drive (fast) and Drive (slow) When you select the Drive Monitor mode, the display will appear similar to the following: MONITOR SETUP DRIVE (fast) Do It! Select Drive (fast) or Drive (slow) by toggling the Parameter button or turning the rotary knob directly under the Parameter button. When ready, press the Value button to start the Drive monitor function you have selected. The STV will automatically adjust the exposure time to capture star images by taking sample exposures and measuring the results. When the best exposure time is calculated, the STV will capture an image and select the brightest star in the frame. At the fast rate, the star's centroid is determined every 200 milliseconds. The fast rate is best for measuring high frequency drive or mount vibrations. At the slow rate the star's centroid is determined every 2 seconds. The video screen will show a graph similar to the screen shot below: DRIVE MONITOR TIPS When the guide star is selected the STV assigns a brightness value to the star. If the brightness falls to a low level the message "Dim" will appear on the top line of the alphanumeric display in place of the Exposure time. If the star saturates the CCD, the message "Bright" will appear. If the guide star is lost or moves too close to the edge of the CCD, the message "Off CCD" will appear. See Appendix C, page 50, for details. The alphanumeric display will report the following information: DRIVE (fast) Exp=50ms RMS xy= 2. 1, 1. 9 arcsec The graph shows the position of the star with time. In fast mode the STV reports the exposure time and the RMS (root mean square) variation in X and Y over the last 16 points. In slow mode the STV reports the peak to peak variation since you began the measurement. For a more explanation of the theory and calculations behind the Drive Accuracy Monitor mode see Appendix C, page 50. 24 Seeing (DIMM) The Seeing Monitor mode uses a Differential Image Motion Monitor (DIMM) technique to measure your seeing conditions independent of your system's optical quality and drive errors. In order to use the Seeing Monitor mode you must make a two-hole aperture mask for your telescope and follow the other special instructions found in Appendix C, page 51. When you have properly set up your telescope for this measurement, select the Seeing Monitor mode. The display will show: MONITOR SETUP SEEING (DIMM) Do It! Enter the seeing monitor mode by hitting the Value button. The software will automatically find the stars, adjust the exposure, and start collecting data. [. . . ] You should be able to use cables up to 100 feet in length but it will vary from PC to PC. Go to your nearest computer store and ask for a 9 pin male to female extension cable. If the dark spots are a single pixel they are typically caused by hot pixels in the CCD saturating and can be removed with the Remove Cool Pixels command in CCDOPS. If they're several pixels wide you should suspect dust on the window and that effect can be removed with flat fielding your images or clean the window with an "air duster". [. . . ]