Tracking difficulties


Thomas Haugh
 

I have finally gotten the opportunity to install my new AP1600.  I am having difficulty getting the tracking accurate.


Symptoms:


Stars trailed on 30 second exposure.

Telescope appears to slew correctly but does not end up on the target.

I have opened the RA gear box and the gear on the motor turns while in sidereal mode.

When parking (to park 4) the telescope does not return to counterweight bar horizontal.


I took two 5 second unguided exposures 5 minutes apart and solved each.  During these exposures

the driver indicated sidereal and the keypad indicated Side.  Info on each follows:

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DATE-OBS = '2016-01-12T02:54:23.00' / [ISO 8601] UTC date/time of exposure start 


Locating stars in image

Looking up stars in catalog

Solving using 1989 image and 703 catalog stars

Matched 314 of 1989 image and 703 catalog stars;

Average residual 0.2 arcsec; order 4

RA 05h 52m 09.2s,  Dec +32° 32' 45.8"

Pos Angle +89° 35.5', FL 1353.7 mm, 1.04"/Pixel


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DATE-OBS = '2016-01-12T02:59:50' / [ISO 8601] UTC date/time of exposure start    


Locating stars in image

Looking up stars in catalog

Solving using 1911 image and 703 catalog stars

Matched 319 of 1911 image and 703 catalog stars;

Average residual 0.2 arcsec; order 4

RA 05h 52m 24.3s,  Dec +32° 32' 48.0"

Pos Angle +89° 35.4', FL 1353.8 mm, 1.04"/Pixel


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Current configuration:

Maxim DL(5.21) -> Astro-Physics V2 Driver v.5.07.02 -> AP1600

The driver display indicates firmware version S.

Using park 4.

Computer to mount is direct straight through RS232. (no USB)

Camera/Focuser control cables routed through the mount. (no obvious external snags)

No connection to mount guide port.


Current telescope:

Orion 10" classical newtonian @ f/5.3 .

SBIG ST10-XME.

I am unsure of the weight, but nowhere near the mounts stated capacity.

The mount is very stiff with the clutches released several turns, but the 

balance 'feels' the same.  I am awaiting a pull scale to further refine the 

balance.


Current date/time verified to PC.  PC time updates via NTP.


Used PEMPRO Polar Alignment to align mount.

Over 5 minutes the application requests corrections to either axis between 0.5-0.7 arc minutes.


Power supply: PS15V12AC

The power supply feeds the mount exclusively.

Voltage reads 14.96 vdc.

The LED on the control box is always red.

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Observations during troubleshooting:


Tracking rate changes from the keypad are reflected on the Astro-Physics V2 Driver.

Tracking rate changes on the driver are not reflected on the keypad T: display.  If the

keypad showed 8=T:Side, it did not change.  However, when the driver indicates stop and

the keypad indicates Side the mount is indeed stopped.  A 5 second exposure trails.  The

keypad Az/Alt does not change while the RA does.  The keypad RA/Dec/Az/Alt 

values match the driver.  I don't know if any of this is pertinent to the tracking problem; just

passing on the observation.

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Any help would be appreciated.


Tom Haugh



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