User manual SBIG ST-7XE

[. . . ] ASTRONOMICAL INSTRUMENTS SBIG Operating Manual CCD Camera Models ST-7XE/XME, ST-8XE, ST-9XE, ST-10XE/XME and ST-2000XM/XCM With High Speed USB Interface Santa Barbara Instrument Group 147A Castilian Drive Santa Barbara, CA 93117 Phone (805) 571-7244 · Fax (805) 571-1147 Web:<www. sbig. com> · Email:<sbig@sbig. com> 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. [. . . ] All the things that were important for good manually guided exposures still exist, including a good polar alignment, rigid tubes that are free of flexure and a fairly good stable mount and drive corrector. Remember that the function of an auto guider is to correct for the small drive errors and long term drift, not to slew the telescope. 2 The Resolution setting in the Camera Setup command combines pixels before they are digitized. This is referred to as on-chip binning and offers increases in frame digitization rates. Page 40 Section 3 - At the Telescope with a CCD Camera One of the reasons that SBIG autoguiders are often better than human guiders is that, rather than just stabbing the hand controller to bump the guide star back to the reticule, it gives a precise correction that is the duration necessary to move the guide star right back to its intended position. It knows how much correction is necessary for a given guiding error through the Calibrate Track command. The Calibrate Track command, which is used prior to autoguiding, exercises the telescope's drive corrector in each of the four directions, measuring the displacement of a calibration star after each move. Knowing the displacement and the duration of each calibration move calibrates the drive's correction speed. Once that is known, the CCD tracker gives the drive corrector precise inputs to correct for any guiding error. When self guiding is selected by invoking the Self Guiding command under the Track Menu, the computer prompts the user for the exposure time for the tracking and imaging CCDs. Once these are entered, the computer takes and displays an image with the tracking CCD, and the user selects a guide star using the mouse. Guide stars that are bright, but not saturating, and isolated from other stars are preferred. When the telescope corrections settle down (usually once the backlash is all taken up in the declination drive) the user starts the exposure by striking the space bar. The computer then integrates for the prescribed time while guiding the telescope, and downloads the image for display. A calibration star should be chosen that is relatively bright and isolated. The calibration software can get confused if another star of comparable brightness moves onto the tracking CCD during a move. Tests at SBIG indicate that the probability of finding a usable guide star on the tracking CCD is about 95% at F/6. 3, in regions of the sky away from the Milky Way. If a guide star is not found the telescope position should be adjusted, or the camera head rotated by a multiple of 90 degrees to find a guide star. Rotating the camera will require recalibration of the tracking function. [Note: CCDSoftV5 software allows SBIG cameras to calibrate and track in any orientation, similar to the STV video autoguider]. 3. 9. 5. Auto Grab The Auto Grab command allows you to take a series of images at a periodic interval and log the images to disk. This can be invaluable for monitoring purposes such as asteroid searches or stellar magnitude measurements. You can even take sub-frame images to save disk space if you don't need the full field of view. 3. 9. 6. Color Imaging The field of CCD color imaging is relatively new but expanding rapidly. [. . . ] If you always keep the return hose outlet near the reservoir level the pump will have no problem raising the water 2 meters (6 feet) off the floor. The limited pressure capacity of the pump is only a problem when you let the water fall back into the reservoir from a significant height above it, such a 0. 3 meter (12 inches). When using water cooling, avoid the temptation to put ice in the water to get the camera even colder. As the cooling booster is designed, the camera will not be cooled below ambient temperature if ambient temperature water is used. [. . . ]