Andy stated;
“Be sure to re-calibrate periodically since the camera angle on the sky will be rotating [field rotation from Alt-Az operation], and your guider calibration will slowly go out of sync and guiding will eventually fail if the camera rotates too far from the angle it was at when calibration was done.
HTH,
Andy”
You bring up a good point within SGPro, that periodic calibration would be needed as the sky rotates the initial autoguider calibration deteriorates.
Within the Sequence Generator, am I able to set a new Calibration of the autoguider to be done before each Target? Is there a checkbox to perform calibration before each target?
However my understanding was that if you had an ASCOM telescope connected to PHD2 that it would automatically scale the dec guiding for you based on the telescope coordinates. Thus making this option “not needed.”
Ordinarily that would indeed be the case, no need for re-calibration in PHD2 when PHD2 has an ASCOM mount connection (or Aux Mount connection for the case where one cannot guide via ASCOM.)
But in Steven’s case – using an alt-az mount – periodic re-calibration will be required to keep the guider from getting too out of sync with the rotation of the camera.
Sorry for my late replies, I’m at the observatory and internet is spotty…
Thanks for pointing out that checkbox.
I actually understood both your responses… I’m not guiding through ASCOM, but since both alt-az scopes, ioptron and the 36-inch, both have a direct ST-4 plug I choose On-Camera and SGP through PHD knows to send guiding to ServoCAT (or ioptron). My ASCOM driver is used to move the scope(s) and for the 36-inch still allow TheSkyX-Pro to adhoc a move as both SGP and TSX go through Argo Navis while in From Planetarium mode.
Because without a field de-rotator, on either the guidescope or the main, my SSAG on the C8 will be field rotating slightly differently than the 36-inch, and so the option to re-cal guiding after every target keeps the differential field rotation between the C8 and 36-inch to a minimum. I would have to use the system to see the integration time is good for 20 minute, an hour, but maybe not at two or 4-hour on the same calibration, idk. Since integration time without field rotation varies as a function of alt-az, so, too, calibration.
Thank you both,
Steven
