Guiding Nightmare - What Went Wrong?

[scitmon]

Last night was my first imaging session of the season and was a very frustrating one.  I setup my rig as usual, but just could not get my guiding to work.  I was using PHD2 and it complained that it could not make big enough corrections to my mount to keep tracking.  I must have checked and rechecked my polar alignment (I use the polar scope and an app to tell me where to position Polaris) 5 times!  

I switched guiding off and took a 90 second exposure and it was actually much better!  Can anyone give me any theories as to what was happening? 

Unguided: 

Guided:

Edited September 8, 2019 by scitmon

[Freddie]

Going to need a bit more info. than that. How is your guiding set up, ST4 or Eqmod? Guide scope or OAG? Cam? How was the calibration? etc etc etc

[scitmon]

I was using eqmod with a zwo 120mm on an skywatcher st80 to guide a skywatcher 80ed ds-pro. The mount was an azeq6. 

 

I used the same settings as i always had in the past successfully. I realise its a long shot to ask on here like this but i wondered if anyone had experienced something similar. 

[scitmon]

Would the fact that my unguided was better than my guided suggest that my polar alignment was not the problem? 

[david_taurus83]

Did you do a new calibration in PHD seeing as you haven't imaged in a while?

[scitmon]

Not initially.  But I did go through the setup wizard again where it took the darks.  Would this have created new calibration data? Not really sure what that process involves.

[michael8554]

If you are not on a permanent setup I would say a Calibration every night is necessary.

Guidescope orientation and scope balance may well be different.

PHD2 will use the previous Calibration from way back unless you force it to make a new Calibration - Shift/Click the Guide button.

Calibrate, then run the Guide Assistant for at least 2 minutes and accept the suggestions. It will also show a reading of your PA which appears to be good in your unguided image.

Also this is worth reading:

https://openphdguiding.org/phd2-best-practices/

Michael

Edited September 8, 2019 by michael8554

[retret66]

Recalibration as suggested then check your PHD2 logs if the mount is responding intermittently and this caused your guide run away and recover.