Just couldn't polar align tonight

[UKJay1971]

Last night was great and imaged for several hours. Used Sharpcap to polar align and it was pretty good in PHD2 until the last hour or so when a periodic error began to develop (the pulses oscillated either side of the x axis in PHD2, but within tolerance). Get set up for this evening - mount levelled etc and then into SharpCap. Took ages for it to get near aligned - it'd ask for an adjustment one way then, when a minor adjustment was made, it'd leap to a huge adjustment in the opposite direction. Got 'aligned' then into PHD where it immediately went off the screen, it was that bad. Tried drift aligning but that was no better. Back to SharpCap ... and so it went on for a couple of hours before I got fed up and packed up.

Anyone else have issues like this? My mount is a Celestron GT EQ mount - it should be capable of reasonable tracking as last night showed - but tonight it just wasn't having any of it. Shame, as it's clear as a bell outside

[Thalestris24]

Hi

How was your PHD2 calibration? It's a bit of a catch-22 - you need a good calibration to drift align but you need to be not too far off PA to get a good calibration. Try running the guiding assistant - it gives useful info regarding drift in ra and dec. Worth checking balance too. Balance usually needs adjusting according to the part of the sky you're pointing at.

Hope you can sort it

Louise

[UKJay1971]

It was poor - I've had a chat with a friend and he suggests that I guide at my scope's native 400mm rather than the 260mm I achieve using a focal reducer as the seeing will overwhelm the reduced star movement. Given today was rather warm and pleasant, and that the temp has plummeted, I imaging there is quite a bit of atmospheric interference at the moment which is affecting the seeing. I'll try again another day - having a red wine now

Thanks for the reply Louise

 

Jay

[Tim]

There's a good few hours ahead to practice

Sorry can't help, but just to let you know we all get nights where things go wrong and infuriate us.

Earlier my CCD camera, filter wheel and OAG slid out of the holder and crashed onto the mat on the concrete obsy floor.

By sheer luck it fell onto and crushed the nosepiece, but could have been a lot worse!

 

[UKJay1971]

Eeeek!!

[Thalestris24]

1 hour ago, UKJay1971 said:

It was poor - I've had a chat with a friend and he suggests that I guide at my scope's native 400mm rather than the 260mm I achieve using a focal reducer as the seeing will overwhelm the reduced star movement. Given today was rather warm and pleasant, and that the temp has plummeted, I imaging there is quite a bit of atmospheric interference at the moment which is affecting the seeing. I'll try again another day - having a red wine now

Thanks for the reply Louise

 

Jay

Hi Jay

I take it you're referring to your ST80 being used as a guidescope? Yes, use it at 400mm though you might be better off with a standard 50mm guidescope - less weight and easier to balance. I use one with my 115mm frac - works fine

Louise 

[ollypenrice]

You're sure it isn't flexure? Make sure the whole rear focuser assembly of the ST80 is tight in the main tube and that all extenders etc are tight. In fact check evrything twice for possible flexure.

Olly

[newbie alert]

Are you using sharpcap through your 400mm fl..

They suggest a fl of no more than 205 i believe..

[spillage]

have you removed your guide camera at any point. I had exactly the same issue and it turned out that I have put the guide camera back in 90 degrees out.

I would get close pa and then make a tiny adjustment and jump from 7 to 50.