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I have mixed feelings about the quality of this image since I always strive to improve myself. What it's come down to is this: I've reached a plateau. I know what to do to make marginal improvements but the cost in time is high. So I present to you my last deep-sky image before retiring this camera from deep-sky duties: M101, a grand-design spiral galaxy.

My chief complaint is the noise level. In order to ensure correct star color rendering affected by saturation I reduced my normal exposure by half. As I've said many times in the past, this lowers your signal-to-noise ratio which you must make up with more stacking. Also, this time I did not go crazy capturing 50+ dark frames per half-degree Fahrenheit like I did with my landmark Bubble Nebula image seen here: viewtopic.php?f=16&t=1090

If I may, I want to address my critics who might say: Brian you talk a big game but you can't deliver. My reply to you is that this is a $250 uncooled camera that has served me well as a learning platform. Due to its inherent limitations I've learned what levers to pull to make positive things happen. In my opinion it is valuable. A lot of my knowledge comes from the friendships I've developed here in this forum and my membership to the American Association of Variable Star Observers (AAVSO) -- highly recommend. I await the delivery of my new camera with excitement.

Captured over two nights: 2019-03-13 and 2019-03-27

William Optics 71mm f/5.9
Altair 290M camera (uncooled)
Optolong LRGB Filters
Unitron Model 142 GEM
The Flatinator
Passive tracking with PEC
No active guiding

Gain 200 (1.74 e-/ADU, FWD: 7100e-, Read Noise: 1.55e-)
Offset: 25 ADU
Exposure: Multiple
Camera rotation: 1.8 deg E of N

Lum: 47x 25s
Red: 82x 30s
Green: 90x 30s
Blue: 76x 36s

Flats: 50x per channel
Darks: 20x per channel
Bias: 50x all channels

Total integration time: 151 minutes
Total time at telescope: 300 minutes

SharpCap 3.1.5219
APP 1.072
StarTools

EDIT: I updated the image here: viewtopic.php?f=16&t=1533&p=8053#p8053

Nice image Brian. I like the detail in the object and the fact that you have retained colours in the stars. How old is the Unitron mount?

Dave

Thanks, Dave.

Black Wikkkett has got an M101 here viewtopic.php?f=16&t=1412#p7373
that shows more detail. Three factors at play: twice the aperture as mine, active guiding, cooled camera less noise.

My mount is 50 years old. I added a stepper motor to R.A. with periodic error correction on a Raspberry Pi. Nothing on DEC.

Brian

Its still a lovely image mate.

Its going to be clear here tonight, so i am out with the QHY10, see what I get.

Thanks, Andy. Good luck tonight. Hopefully my camera will arrive soon. I'd like to get another chance at M101.

Like the rig Brian - some engineering and programming gone into that.

Dave

Nice image

Oh no , high cirrus

What camera are you getting Brian (sorry if youve said previous ).

Thanks, Mr Wikkett, but not as nice as yours.

Andy, I'm taking the plunge into CCD. I did my own analysis of high read noise inherent in CCDs and concluded that its effects are largely mitigated by having the 16-bit A/D. We'll see!

Brian