Observation by Mike Greenhill-Hooper: M65 EAA image
Uploaded by
Mike Greenhill-Hooper
Observer
Mike Greenhill-Hooper
Observed
2022 Mar 07 - 22:15
Uploaded
2022 Mar 09 - 11:05
Objects
M65
Planetarium overlay
Constellation
Leo
Field centre
RA: 11h18m
Dec: +13°05'
Position angle: -40°01'
Field size
0°10' × 0°07'
Equipment
- Telescope: 20" f/4 Obsession Dobsonian with Paracorr coma corrector
- ASI294MMPro CMOS imaging camera
Exposure
5x5min "live capture" on SharpCap Pro; 2s exposure, gain 450, -15C, dark subtraction
Location
Miradoux, S.W. France
Target name
M65 in B&W using SharpCap Pro Live Stacking
Title
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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