Incorrect SBIG AO set-up with the Pyxis 2" rotator.

[fehner]

ACP with HF9, MaximDL 5.7, Pxis 2" rotator, and SBIG AO8 unit. It appears that ACP is setting the wrong bump codes in the AO8 when the rotator driver is set to reverse. The sets up the correct sky position angle but the AO unit bump set-up is 180 degree wrong.

PA = Sky Position Angle.
RA = Rotator Angle.
AO Calib. = Drive settings in the Maxim AO window after an AO drive calibration at the indicated PA.
ACP = Drive settings in Maxim after ACP sets them during a run.
1 = true.
0 = false.

PA RA Rev X Rev Y Swap Motor Axis Drive setting source

0 90 1 0 0 AO Calib
0 90 0 1 0 ACP

90 180 1 1 1 AO Calib
90 180 0 0 1 ACP

180 270 0 1 0 AO Calib
180 270 1 0 0 ACP

270 0 0 0 1 AO Calib
270 0 1 1 1 ACP

It appears that ACP is setting the AO drive variables 180 degrees off. Does anyone know if this if a known bug in HF9. The Help files claim that ACP works with a rotator and an AO unit in this version.

Thanks,
Barbara Fehner

[fehner]

I managed to get some additional data from the opposite side of the pier.

Mount on East side of pier, telescope looking west.

PA, RA, Rev X, Rev Y, Swap Motor Axis, Drive setting source

0, 270, 1, 1, 0, AO Calibration
0, 270, 0, 0, 0, ACP

90, 0, 1, 0, 1, AO Calibration
90, 0, 0, 1, 1, ACP

180, 90, 0, 0, 0, AO Calibration
180, 90, 1, 1, 0, ACP

270, 180, 0, 1, 1, AO Calibration
270, 180, 1, 0, 1, ACP


Barbara

[Bob Denny]

Barbara --

Excellent detective work, and an excellent post with the results. Very clear, thanks.

HF9 is running on lots of AO systems, and I specifically checked out in great detail at the New Mexico Skies 24" before releasing it. So it should be working there. The big question is why the 180 degree error on your system? Offhand, why is there a 90 degree difference between the rotator angle and the sky PA? FYI, ACP will account for such differences when rotating by keeping track of this difference in RotatorInfo.txt. The AO bump polarities are set using the sky PA (from the plate solution of the pointing update).

I think you are using an internal guide chip? Is there possibly something unusual about your optics? I can't remember what scope you have.

[fehner]

Thank you for the reply Bob. I think I have found the problem but can't be sure until someone else tests the fix with other equipment. After I went through the code as much as I was able to I believe that the AO rotation vectors in the standard conditions table are incorrect. It appears that the vectors for 0 and 180 degrees are interchanged as are the vectors for 90 and 270 degrees. I changed the vectors in the table and then managed to make one complete run at PA of 0,90,180, and 270 degrees on both sides of the pier. I changed the bump setting for the AO to + and - 10% and set the exposure time to 10 minutes. The run completed with no errors and the mount bumps were correct for each PA.

My telescope is a LX200ACF with two reflections and the camera is a ST10XME using the internal guider chip. This fix needs to be tested using a Pyxis 3" rotator that moves in the normal direction and also with an off-axis guider. I could very well have missed something that is a root cause since I have never used Java script.

I can not do any more testing now since my Windows 7 computer has crashed now and after a Clean Windows 7 reinstallation and reinstallation of Maxim and ACP the ACP telescope hub will not show up in Ascom Chooser. I have no idea of why this is or what to do about it but without it I can not use a Planetarium program or FocusMax and that shuts me down. BTW the same situation exists with my laptop with Windows 7 64 bit.

Here is my correction:

function Rotate(PA)
{
var r0 = [true,true,false]; // Changed bump polarities, Barbara Fehner
var r90 = [true,false,true];
var r180 = [false,false,false];
var r270 = [false,true,true];
var rot = [r0, r90, r180, r270];
if(PA >= 360.0) PA = PA - 360; // Range 0 <= angle < 360
if(PA < 0) PA = PA + 360;
var paq = Math.round(PA / 90.0); // PA in quadrants
if(paq == 4) paq = 0; // Handle wrap to 0
return(rot[paq]);

}

Barbara

PS Starry Night will show a PA of 360 degrees which causes a script error in the ACP Plan checker and will halt the run.

[Bob Denny]

Barbara --

If that works for you then that's great. but I can't make those changes to the production code because it would break all of the other systems that are working, with both OAG and internal guiders (which have different polarities).

On your behalf, I'll ask on the premium forum for others who are using a 2 1/2" rotator.

I'm quite curious as to why it's happening there.