Meade #1220 Field De-Rotator, for 7", 8", 10" and 12" LX200 & LX200GPS Models
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• Meade Model 1220 Field De-rotater for Meade LX200GPS Telescopes
• Meade LX200GPS telescopes may be operated in the altazimuth mode (i.e., without polar alignment) for all visual applications and for photographic or CCD imaging exposures of up to about five minutes duration.
• Most LX200GPS owners use their telescope in the altazimuth mode the great majority ofthe time. During longer photo or CCD exposures in the altazimuth mode, however, an effect called field rotation becomes evident.
• Simply put, even if the telescope is perfectly guided on a central star during along exposure, stars at the edge of the field appear to rotate about the field center during the exposure. As a result, stars away from the field center appearas small concentric arcs on the film, rather than starpoints.
• This effect, which in no way relates to the accuracy of the telescope's computer or internal alignment, occurs on all altazimuth-mounted telescopes, whether large observatory telescope or LX200GPS, and is caused by the telescope not being polar aligned.
• Field rotation with an LX200GPS (or with their predecessor LX200 models) can be cured with the simple addition of an equatorial wedge the wedge enables precise polar alignment, negating all field rotation. Alternately, the optional #1220 Field De-rotater may be attached to the rear cell of any 7", 8", 10", 12", or 14" Meade LX200 or LX200GPS model, simplifying field operation of the telescope,since no wedge is required. With the #1220 De-rotater attached to the telescope's rear cell, other accessories (T-Adapter, Off-Axis Guider, etc.) can in turn be threaded to the #1220 unit.
• The #1220 is easy to use! Just align the LX200GPS telescope as usual, using the GPS alignment procedure or one of six other available alignment procedures, and,automatically, signals are fed through one of the RS-232 ports on the LX200GPS control panel to the Field De-rotater, causing it to rotate at the correct speed and precisely counter the effects of altazimuth-induced field rotation. The #1220 Field De-rotater is powered through connection with the RS-232 serial port.