A couple of galaxy compositions here. They combine most of the frames that I took over the Spring of M101 and M51 using an 8 inch Newtonian at F ~ 5.0. RGB was collected with an OSC camera and no filter. HA collected using a mono camera with the image then added into the red channel.
In each case about 2/3 of the frames were collected on moonless nights from a Bortle 6 site and the remainder on a moonless night from a Bortle4 site. The final integration was weighted according to the measured SNR. Thus, despite constituting only a third of the total, the weighting of the dark sky frames meant that they contributed about 70% of the final signal. The Bortle 4 SNR was about 4 fold higher than at Bortle 6. However seeing was relatively poor at the Bortle 4 site. Thus the pictures are weighted more towards trying to detect the full extent of the galaxies rather than towards getting high resolution to the core.
SW200 PDS Newtonian, Baader flattener F 5.0. CEM70 mount, ASI120MM guide camera (50 mm, f = 160mm guide scope)
PDH2 guiding, Sharpcap (livestack) capture, PixInsight pre and post processing
ASI294 PRO MC camera, gain 124 at -10C
ASI294 PRO MM camera, gain 124 at -10C
Optolong 7nm HA filter
Image 1 of M51 is 210 x 40s plus 54 x 70s RGB frames plus 9 x 3 min of HA
Image 2 of M101 is 243 x 40s RGB frames plus 19 x 3 min of HA
Image 3 of M101 is the same as 2 but without HA and also annotated
One thing that I learned from this was that darker skies make an enormous difference to how quickly you can get to a high SNR image ...BUT ..it also helps if the seeing is good.
Tim
Left overs from galaxy season. RGBHa of M51 and M101
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Please upload large images to photo sharing sites (flickr, etc) rather than trying to upload them as forum attachments.
Please share the equipment used and if possible camera settings to help others.
Please upload large images to photo sharing sites (flickr, etc) rather than trying to upload them as forum attachments.
Please share the equipment used and if possible camera settings to help others.
Left overs from galaxy season. RGBHa of M51 and M101
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- CaptureM51_3.JPG (70.42 KiB) Viewed 837 times
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- Capture_M101_2.JPG (147.46 KiB) Viewed 837 times
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- Capture_M101_3.JPG (190.66 KiB) Viewed 837 times
Re: Left overs from galaxy season. RGBHa of M51 and M101
Whish I had left overs like that
Darker skies are something I still have to try with my setup but can imagine it makes a difference.
Menno
Darker skies are something I still have to try with my setup but can imagine it makes a difference.
Menno
Re: Left overs from galaxy season. RGBHa of M51 and M101
Tim, I love your M101. I tried it a couple years ago. Disappointing. I gotta get me a bigger aperture!
Brian
Brian
Re: Left overs from galaxy season. RGBHa of M51 and M101
Thank you for the comments. I was pretty pleased with the M101 images especially since much of it is quite faint - never quite sure how far to go with imaging time and at what point it is just diminishing returns. The annotation tool is useful I think because it defines a circumference for each galaxy and I suppose that when your picture approaches that then there is not much further extent to find. The fast optics also help but it is quite a big set up to travel around with.
Tim
Tim