Messier 101 and SN 2023ixf

[Alexp]

After many, maaaany months of not being able to image due to bad weather it has finally cleared up over the past month.. Even though there is only little astro darkness currently, I couldn't wait any longer since I really had the itch to image something in the night sky. There have been many pictures of it already, but I also wanted to have a go at M101 with the current visible supernova as I have never yet imaged an event like this. 

Altogether I managed around 12h of imaging time at 60s exposures in a Bortle 6/7 zone (unfortunately a lot of extra light from neighbours' windows) over the course of five nights with my SW 150pds and ASI533mc pro on my AVX (kind of pushing the weight limit on it for astrophotography). Oddly enough I found that decreasing my guide exposure setting from 2 seconds to 0.5 seconds in PHD2 gave me better guiding results on the AVX overall, which went below 0.8" RMS error. The stars are slightly egg shaped - with my half-knowledge I am assuming that this may be the result of (maybe) the cooling fan of the 533mc pro vibrating and bad collimation. Testing will be necessary to find and remedy the issue(s).

After countless hours of integrating 730 frames on my laptop and post processing the final result in PI I believe I have a version now with which I am happy, though I might still try and image M101 with the ZWO duoband filter to add some Ha to this image. 

Comments and critique are very welcome, hope you guys like it and I wish you all clear skies!

Cheers,

Alex 

[windjammer]

Hi - interesting note on your guiding frequency.  I guide at 10-20ms exposures and 100ms interval and get sub arcsec rms (normally!).  If the mount is unruly, then hanging around for a multi sec exposure won't work.  The earlier and smaller you catch a drift and correct the better.  

I don't totally buy into the 'chase the seeing' thing.  What I have seen is resonance between exposures and the mount having time to move to its new position.  So important  to have an interval between guide exposure - correction issued - next guide exposure.  No point in guide exposures while mount is moving to correct.  Good thinking for playing with the guide parameters!

Oh yeah - great pic IMHO!  Good detail (almost) right to the centre.

Simon

[Alexp]

Thanks for your kind words Simon! I do think I would be able to get the details a tiny bit sharper once I solve the issues in my optical train. 

As opposed to buying my way out of the problems I always try to experiment, even in hopeless situations, just to see if there is a difference. Plus I am hoping that this way I will understand all the mechanical and software related issues a bit better. 

I always thought that it would be better to have longer exposure settings in PHD2 but trying it out differently once now really seems to have had an influence, at least for my setup and the circumstances around my setup. 
I was, however, not aware that it is possible to control more variables than just guiding exposure (guide exposure - correction issued - next guide exposure)? You are also using PHD2 and an AVX? I am assuming these settings are plainly visible and I am just not aware, which most often is the case for me ^^. 

Cheers,

Alex

[windjammer]

Yes PHD2, but using ST4 interface through ZWO guide cam, as opposed to ascom or anything like that.

PHD2 enbles you to control the interval between guide exposures, go Guide tab ->Advanced Settings -> Camera tab -> Time Lapse box

The guide correction is issued as soon as the guide exposure ends.  The next guide exposure starts after the time lapse has expired.

Simon

 

[Alexp]

Thanks! I'll have a look into that and see if changing some of these variables have a positive influence on guiding! 

Cheers