NGC 2841 - A Flocculent Galaxy in Ursa Major
NGC 2841 - A Flocculent Galaxy in Ursa Major
NGC 2841 - A Flocculent Galaxy in Ursa Major
NGC 2841 is a large flocculent galaxy that is over 150,000 light years in diameter. At a distance of "only" 46 million light years, the galaxy is a relatively nearby neighbor of ours. NGC 2841 exhibits some unusual galactic features including a decoupled nucleus and a polar ring. These oddities are believed to be the result of an earlier merger with a smaller galaxy.

In the upper right of this astrophoto is the background galaxy PGC 26572. In addition to a multitude of smaller background galaxies, the wider field version of this image shows about a dozen more PGC galaxies (as identified in the annotated version).

In this image, North is down. This image is cropped to 39% of the original full frame.

Exposure Details
Lens Nikon 600mm f/4 ED IF
Focal Length 600mm
Focal Ratio f/6
Mount Schaefer GEM - 7 1/2 inch Byers gear
Guiding QSI 690 OAG, Lodestar Autoguider, PHD2 Guiding, Starlight Xpress Adaptive Optics @ 5-10 Hz
Camera QSI 690wsg-8 (set point -10C) with Astrodon Gen II Series E LRGB filters
Exposure Lum: 61x600 binned 1x1, 136x300 binned 2x2; RGB: 22x22x22x300 binned 1x1 (27 hours total exposure)
Calibration 50 darks, 40 flats, 200 bias
Date December 2, 3, 4, and 5, 2016; January 25, 26, and 27, 2017
Temperature 12/2-28F, 12/3-45F, 12/4-42F, 12/5-38F, 1/25-23F, 1/26-21F, 1/27-39F
SQM Reading Bortle 4 on all nights - 12/2-21.50,12/3,-21.50, 12/4-21.35, 12/5-21.60, 1/25-21.60, 1/26-21.55, 1/27-21.45
Seeing 3/5 on 12/2, 12/3, 12/4, 1/26 and 1/27; 4/5 on 12/5 and 1/25
Location Pine Mountain Club, California
Software Used Images Plus 6.0 and Sequence Generator Pro 2.6 for camera control. Plate Solve 2 for plate solving. Images Plus 6.5 for calibration, stacking, ArcSinH stretching, adaptive Lucy-Richardson deconvolution, and star size reduction. Photoshop CS5 used for levels and curves, lab color, saturation adjustments, selective color, match color, high pass filter, and screen mask invert. Gradient Xterminator for gradient removal. Carboni Tools for additional noise reduction and smoothing. HLVG for additional color correction. Registar 64 for subexposure alignment. Focus Magic for focus restoration. Pixinsight 2.8 for image annotation.
Notes NGC 2841 has some very fine details and my focal length (at only 600mm) for capturing these details is less than ideal. Nonetheless, I was very happy with the quality of details I was able to capture, and the color of both the galaxy and stars seems very good to me.

I invested a lot of exposure time in order to capture as much of the extended halo as possible. While I was successful with that, I suspect I could have had 90% as good an image with about half the exposure time!

This image was published by Astronomy Magazine as its Picture of the Day for September 15, 2017!

And, then it was published again by Astronomy Magazine for it's Picture of the Day for October 12, 2017!