Missing something in "North Polar Calibrate" procedure

Joe Zeglinski


I'm a bit confused about a step in this procedure - perhaps somebody can tell me what is really going on with the Keypad program.

In following the "N Polar Calibrate" series of steps,
Step #3 tells me to "move the scope by hand" to the calibration star, then use the "NEWS" buttons to centre the star in the eyepiece.

Now this seems really odd.
Having just commanded the system to Park Position #3 as the zero reference (pointing at Polaris, with counterweight down), then "unlocking the axes" and pushing the scope to the calibration star, while the servos are still pointing at Polaris, I am supposed to (finally) jog the target into the centre of the FOV using the NEWS buttons.
Doesn't this last step of using the NEWS buttons, ruin the initial Position #3 servo reference?
It effectively adds a delta RA/DEC to the zero reference, even before the ALT/AZ manual adjustment on Polaris, can be made.

Perhaps this NEWS button bias doesn't add that much error to the procedure in exchange for a bit of user convenience, and will eventually be iterated out after a few swings?

Another point, I really don't see the NEED to "manually push the OTA" to the calibration star. It seems to me that if the system is set in Park Position #3, I should be able to tell the firmware to do a GOTO to the selected calibration star, and I would then simply add the NEWS button RA/DEC delta when it got there.
Surely, with all the location and date/time information, and a known starting reference point (Park #3), it really doesn't need my unlocking the axes and pushing the OTA. The firmware should be capable of pointing the scope somewhat automatically.

This would be a lot easier since I wouldn't need to reference a star atlas, or hunt the light polluted skies for the target (assuming my selected calibration star actually is out of the tree line). Actually, the firmware could also narrow the possible choices, and suggest a much shorter list of "optimum" calibration star candidates, with the best RA & DEC separation from Polaris.


This brings up another question - why aren't the RA & DEC displayed for the selected calibration star candidates?

In fact, the coordinates aren't even listed in the Appendix "D" of calibration stars of the KEYPAD user guide - just names, designations, and magnitudes. That doesn't help much in knowing the suitability of the choice, other than if it might possibly be bright enough to find. The "N Polar Calibration" procedure only displays names of stars on the Keypad, which then requires my hunting up the coordinates in a book or laptop, before deciding if it has a suitable difference in RA/DEC from Polaris.

Perhaps I have missed the button sequence to display these coordinates before committing the calibration candidate star to be the target. There must be an easier way.

Thanks for any advice,

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