Bad night at the Office

[valleyman]

Over the last few weeks I have been getting back into Astronomy. Got kitted out with a new Sky-Watcher AZ EQ5-GT, skywatcher 120 ED Pro and WO 81 ED Pro. Guiding with a ZWO 30mm mini guide scope and a ZWO 120 mini Cam. Also using a ZWO ASI533mc as the capture Cam.

I am using ZWO ASIair Pro for the software guiding and capture.

Ove r the last weekend had some good results with the WO81 mounted and using the Mini set up getting 20x3minute exposers and near perfect Tracking staying within the 2" perimeters of the guide graph with ASIair. Happy Bunny lovely round stars from M13.

However last night I had the 120 mounted but everything else was as before. Mount is level and within 1 degree of Level. Polar aligned using ASIair Pro PA tool.(Fantastic bit of kit). GOTO M51 and Plate Solved with in 10 seconds. Guide scope in focus and star selected for guiding.

Then disaster. After about 10 seconds of guiding the graph goes haywire with the RA and DEC scales going of the Graph.

 

Tried again from the start and again. No change.

Stripped the ASIair out and switched over to PHD and APT to try again. PHD came up with the message that there was no tracking in RA.

Now have to admit that I had not used PHD with this setup before so I am not sure I had that set up correctly but with both systems having guiding problems my thoughts are with something amiss with the Ratio between the SW120 and the ZWOmini. As already stated it worked perfectly with the WO81 mounted.

All the locks, clutches etc etc were tight. This is my 10th year in Astronomy so not a Novice. The scope was set up in daylight and tested long before night fall.

Any advice appreciated

Pat

[kirkster501]

I have seen this issue before too.

Did you calibrate PHD properly?  Has it remembered the calibration from another scope setup and is using that instead of the current one?  With my mobile rig it needs to be calibrated every time I set up or else I get issues like this.  Did you calibrate near the Celestial equator which is the best way to do it?

[valleyman]

I'll have a look at that on the next clear night. Thanks for the tip about Calibrating. But the problem was on both the ASIair and PHD.

🥴. 

[valleyman]

Update . 

The fault was that the drive wheel on the DEC stepper motor had come disconnected from the drive shaft. In the process of getting a new part from FLO