Black Eye Galaxy - M64

[halli]

Latest imaging attempt on M64 which is conveniently placed from my location in Reading at the moment.  

Only managed 8L and 3 each of RGB at 600s each with an Atik 383l and GSO RC8 during a clear period recently.  

I am relatively pleased with the galaxy but if someone would help explain some of the heart shaped star shapes I would really appreciate it !   Collimation, or tilt ? - I don't think the tracking is the issue

Thanks for any info leading to the arrest of the unwanted criminal involved with causing this defect !!!

 

 

[mikeyscope]

 

That's a really fine image with good detail in the galaxies 'black eye' dust lanes.

I see what you mean about the stars ...not too bad, maybe try re-checking collimation before doing anything drastic.

 

So if you do need to do something more drastic check out this thread by Doug (Silentrunning), hopefully be of some help in resolving your issue... 

Mike

[laudropb]

Very nice image.

[halli]

Thanks Mike and Laudropb. 

I have noticed that the star shapes get better in some subs which points to perhaps mechanical issues with focusser  loading during certain orientations during the imaging run.  Thanks for the links I hope I don't need to go that far.  I think I will play around with the camera positioning first and collimation  to try and identify the cause

[ollypenrice]

Triangular stars often arise from pinching of mirrors and lenses but can be created by other means. I was trying to collimate one of these RCs last week and it was difficult to say the least! It tended not to do what the text book said it would do and is still not right...

I like your Blackeye. You've found the outer disk to be blue whereas it came out the same creamy colour as your inner part for us. Who knows?

Olly

[PeterCPC]

Really nice image - hope you get the stars sorted out.

Peter

[halli]

Thanks Olly and Peter.  I don't seem to have found collimation too difficult usually if I tweak the secondary a bit it seems ok with a Cheshire and a star.  However I need to spend longer at it but am always keen to start imaging at the expense of fiddling.  I have ordered an artificial star which I can hopefully use at my leisure to ensure the collimation is accurate and rule it out.

[MartinB]

That's a nice black eye, hope you get the stars sorted.  

[fwm891]

I think its a mixture of both. I have the Altair/GSO 8 inch RC and have had this same imaging problem. You need to tilt the image plane to point straight at the secondary, then tilt the secondary to reflect straight back at the image plane before finally correcting the primary. I use a 2 inch Gatter laser with the standard pencil beam and the ringed pattern. I use a small mirror placed inside the OTA resting against the end of the baffle tube so I can see just where the laser's pencil beam is striking the secondary (mine has a central etched circle as a target) Having adjusted the tilt of the camera plane you can move to the secondary - great thing here is that the laser pencil beam has its own diffraction rings and when your adjusting the secondary to return back on itself these diffraction rings are just visible around the returned beam having been expanded by the secondary. Now I use the ringed filter on the laser and adjust the primary to produce a symmetric pattern projected on a wall/screen in front of the scope. Finally tweak against the stars...

http://www.deepskyinstruments.com/truerc/docs/DSI_Collimation_Procedure_Ver_1.0.pdf

Use the star images towards the back of this pdf to identify the final tweaks needed. I put a brightish star (2nd mag) in the corner of a frame ( each corner) and look at them to see if there is a trend in the oblateness of the doughnut shape and work from there rather than the open cluster image the article uses.

[halli]

Thanks Martin and fwm.  I will certainly look into collimation techniques.  Thanks also the people who pressed the like button !