Observation by Mike Greenhill-Hooper: M65 EAA image

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Mike Greenhill-Hooper


Mike Greenhill-Hooper


2022 Mar 07 - 22:15


2022 Mar 09 - 11:05



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Field centre

RA: 11h18m
Dec: +13°05'
Position angle: -40°01'

Field size

0°10' × 0°07'

  • Telescope: 20" f/4 Obsession Dobsonian with Paracorr coma corrector
  • ASI294MMPro CMOS imaging camera

5x5min "live capture" on SharpCap Pro; 2s exposure, gain 450, -15C, dark subtraction


Miradoux, S.W. France

Target name

M65 in B&W using SharpCap Pro Live Stacking


M65 EAA image

About this image

I have been wrestling with imaging small deep sky targets with my SCT (Celestron C11) for sometime.  The problem is the need to autoguide via an OAG. I have difficulty finding bright enough stars near to the object and then they often look distorted even though I have tried working close to the correct back focus.  PHD2 struggles a lot and the final images are not great, either at f/10 or with focal reducer at f/6.3.  So I have now made my first attempts to image with my light bucket Dobsonian (20", f/4).  It has Goto and is motorised (ServoCat + ArgoNavis), but autoguiding is not possible (without a lot of effort).  The attached is a stack of 5 separate 5 minute live stacks captured with SharpCap Pro of M65.  No autoguiding is necessary.  I just had to pause the stacking process between the 5 minute stacks and move the mount slightly with the hand controller and then resume the stack. Subtraction of previously recorded dark frames is made automatically.  I didn't bother with flats subtraction. The light gathering power of the telescope and the sensitivity of the camera meant that at a focal length of 2000mm a small magnified field of view is possible with short exposures and consequently sharp images can be obtained.  The attached were taken just with a uv/IR blocking filter.  My next step will be to see if I can take separate RGB stacks and try and combine them without saturating the final image.  I had previously thought that "EAA" - electronically assisted astronomy was a bit of a compromise, but I find the results are better than I could obtain with my poorly auto-guided C11.

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