|
Guiding nightmare
I am reposting this image of my best PHD graph - because I have been unable to replicate it since.
My guiding setup details:
QHY5 (5.2 micron pixels, 1280x1024)
Skywatcher 70mm f7.1 achro (f=500)
Guiding image-scale: 2.14 arcsecs/pixel
Guided 'on-camera' via PHD
Mount: Orion EQ5 fitted with synscan goto, driven by EQMOD via USB-Serial/PC Direct mode on handset.
I don't have any screen shots of my more recent guiding attempts - I was too busy trying to figure out what was going on, but it would proceed through the calibration, but as soon as it started guiding, the guide star would wander off. The mount sounds like it is trying to keep up - the DEC motor is pretty distinctive, not sure about RA though.
Sometimes the RA and DEC graphs would head off in different directions and just keep going until the star was lost, other times one trace or the other would head off the chart...
At the moment my prime suspect is my guiding cable from the camera to the motor controller, as I can slew via EQMOD etc. I have tried guiding with EQMOD, but I am not sure of the settings, so although I couldn't get that to work either, I am less sure of where the problem lies with that approach - but I suspect it is more with my lack of knowledge.
My next step - after reading some helpful advice given to another guiding newbie by Marc (multiweb) is to graph just the tracking of the mount by turning off the guide output in PHD, and see what I get.
What else can I do to track down the problem?
Where do I get another guiding cable - is there anything I can substitute - phone cable?
Am I right in thinking that the graph below at a scale of 2.14asp is pretty good for an EQ5?
Thanks
Adam
|