M13 - Just before the clouds rolled on top of me

[rodrigol]

Below is M13 taken with my experimental rig: C11 Edge HD + 0.7 FR + Celestron OAG w/ QHY5L-IIM + 0.5 FR. Processed with DSS and PI. Calibrations frames from my library. The main camera is an ASI1600MC (not Pro/Cooled). 30 x 60s subs of which only 8 has nice round stars. The rest where eggs, yeasty-like shapes nonsense. I tried to make some sense of these but knowing they would spoil the core of M13 did not motivate me to attempt any correction. The mount seems to track relatively well and the guide setup /w the 0.5 FR is sensitive and always seems to find stars to guide on. Without this FR there is a different and frustrating story to tell. But my issue is that every once in a while, the star goes for a couple of seconds, or the mount slews/drifts (according to PHD2) when it is actually not. I've got to try normal ST4 guiding to compare.  Oh! And I know that the PI deconvolution is a tad overdone 😐

As always comments are more than welcome 🙂

 

[DougM43]

That’s nice,, I like the star colours 🙂 gives it some depth.

[kirkster501]

Well done -  a very good effort and a nice picture   

You have to get the guiding sorted out to progress this because you have to get more data to get the image to sing out more.  Guiding at that FL is a none trivial matter, even with the reducer.

There's a strange noise effect in there....  I think you may be oversharpening to compensate for the guiding difficulties.

[rodrigol]

HI,

Thanks for the comments 😀 The guiding is proving challenging but I hope to eventually get there. I'm just praying there is nothing wrong with the mount and that careful calibration of the guiding setup in PDH2 will deal with most or all of the gremlins. One piece of info that is eluding me is the correct FL to input in PHD2. I'm using 1960mm , which is the theoretical value many have calculated for the optical train I have, but that does not include the OAG (does it matter?). The QHY5L-II has now a 0.5 FR at 28mm which really make a difference when getting hold of guide stars. So, I've trying around this value. BTW, my PHD2 mx values are set at 5000 and the RA and DEC agr are at 100. This seems to get guiding to be stable for some of the 60s frames, but not for the majority of frames. To make sure the mount is 'ok', I will try ST4 guiding as soon as possible.

 

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[rodrigol]

Follow-up: I discovered play on the RA axis and a lot of backlash on the mount, which I set out to fix. Sadly, I got a vout of kidneys stones that have taken 4 weeks to get sorted. The RA play has been sorted by careful adjustment of the wormgear hex screws and I've also replaced the cgem saddle with the human friendly one from ATM. I've now got a very smoothly balanced mount with a much easier means of balancing the OTA. Only the weather is standing between my setup and the next picture. 

 

 

[kirkster501]

Sorry to hear of your health issues.  Glad you are on the mend.