Celestron CGE800, CGE925, CGE1100, CGE1400 manual Declination Drift Method of Polar Alignment

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Declination Drift Method of Polar Alignment

This method of polar alignment allows you to get the most accurate alignment on the celestial pole and is required if you want to do long exposure deep-sky astrophotography through the telescope. The declination drift method requires that you monitor the drift of selected stars. The drift of each star tells you how far away the polar axis is pointing from the true celestial pole and in what direction. Although declination drift is simple and straight-forward, it requires a great deal of time and patience to complete when first attempted. The declination drift method should be done after any one of the previously mentioned methods has been completed.

To perform the declination drift method you need to choose two bright stars. One should be near the eastern horizon and one due south near the meridian. Both stars should be near the celestial equator (i.e., 0° declination). You will monitor the drift of each star one at a time and in declination only. While monitoring a star on the meridian, any misalignment in the east-west direction is revealed. While monitoring a star near the east/west horizon, any misalignment in the north-south direction is revealed. It is helpful to have an illuminated reticle eyepiece to help you recognize any drift. For very close alignment, a Barlow lens is also recommended since it increases the magnification and reveals any drift faster. When looking due south, insert the diagonal so the eyepiece points straight up. Insert the cross hair eyepiece and align the cross hairs so that one is parallel to the declination axis and the other is parallel to the right ascension axis. Move your telescope manually in R.A. and DEC to check parallelism.

First, choose your star near where the celestial equator and the meridian meet. The star should be approximately within 1/2 an hour of the meridian and within five degrees of the celestial equator. Center the star in the field of your telescope and monitor the drift in declination.

If the star drifts south, the polar axis is too far east.

If the star drifts north, the polar axis is too far west.

Make the appropriate adjustments to the polar axis to eliminate any drift. Once you have eliminated all the drift, move to the star near the eastern horizon. The star should be 20 degrees above the horizon and within five degrees of the celestial equator.

If the star drifts south, the polar axis is too low.

If the star drifts north, the polar axis is too high.

Again, make the appropriate adjustments to the polar axis to eliminate any drift. Unfortunately, the latter adjustments interact with the prior adjustments ever so slightly. So, repeat the process again to improve the accuracy checking both axes for minimal drift. Once the drift has been eliminated, the telescope is very accurately aligned. You can now do prime focus deep-sky astrophotography for long periods.

NOTE: If the eastern horizon is blocked, you may choose a star near the western horizon, but you must reverse the polar high/low error directions. Also, if using this method in the southern hemisphere, the direction of drift is reversed for both R.A. and DEC.

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Contents CGE800 CGE925 CGE1100 CGE1400 User Defined Objects Telescope Maintenance Some of the many standard features of the CGE include CGE 1400 Shown 12v Output JackCounterweight Setting up the TripodPower Supply DiagonalAttaching the Center Leg Brace Attaching the Electronics PierCounterweight Locking Screw Safety Screw Washer Installing the Counterweight BarInstalling the Counterweight Attaching the Equatorial MountDovetail Slide Bar Dovetail Locking Knobs Mounting Platform Attaching the Optical Tube to the MountAttaching the Visual Back Installing the Star Diagonal Installing the EyepieceInstalling the Finderscope Adjusting the Mount Moving the Telescope ManuallyBalancing The Mount in R.A Balancing The Mount in DECTransporting the CGE Powering the TelescopeAttaching the Motor Cables Page CGE Hand Control Double Stars Named StarsNamed Objects Variable StarsAlignment Procedures Startup ProcedureAuto Two-Star Align Auto One-Star AlignCGE Re-Alignment Quick-AlignLast Alignment Slewing to an Object Object CatalogSelecting an Object Finding PlanetsDirection Buttons Tour ModeConstellation Tour Rate ButtonSetup Procedures Identify Scope Setup Features Precise GoToObserving Tip Helpful Hint Utility Features Helpful Hint Page CGE Ready Image Orientation Determining Field of View FocusingCalculating Magnification General Observing Hints Celestial Coordinate System Motion of the Stars Latitude Scales Pointing at PolarisFinding the North Celestial Pole Declination Drift Method of Polar Alignment Observing the Planets Observing the MoonLunar Observing Hints Planetary Observing HintsObserving Deep Sky Objects Observing the SunSolar Observing Hints Seeing ConditionsSeeing Short Exposure Prime Focus Photography Eyepiece Projection FullLong Exposure Prime Focus Photography Planet ISO Moon Mercury Venus Mars Jupiter SaturnPeriodic Error Correction PEC Using Periodic Error Correction Reducing Vibration Terrestrial PhotographyMetering CCD ImagingFastar Compatible Optical System Fastar F/2 Imaging Planetary or Lunar With Reducer/CorrectorMedium size to small galaxies Auto Guiding Care and Cleaning of the Optics CollimationCollimated telescope Should appear Symmetrical with Page At f/10 and 163 power with the CGE Page Technical Specifications Idle Current Appendix a Longitudes Latitudes Georgia Minnesota Rhode Island Canada Appendix B RS-232 Connection Communication ProtocolAdditional RS232 Commands Reset The Position Of Azm Or AltAppendix C Maps of Time Zones Page Page Page Page Page Page Page Celestron TWO Year Warranty