Another clear night ...
The forecast for Wednesday April 23rd was promising. Therefore, our club's observatory directory decided Wednesday would be our imaging special interest group's session for the week that night. I could not attend as I had work meetings that night. However, I was able to join the group via Zoom and contribute to the night's imaging efforts while still attending to my work commitments. T skies were not the best but clear enough to image. With no Moon until four in the morning, we decided to go after a broadband target like a galaxy. I wanted to go after M64, The Black Eye Galaxy. Another member of the group suggested M109, a Barred Spiral Galaxy in Ursa Major. They made a better case than I did, and the group decided on M109. I'm glad they did. It is a very beautiful target.
After solving the usual array of issues that come with operating the observatory so infrequently, we began imaging at 9:24 PM and imaged until 10:54 PM. We captured data with both the NP101is and ZWO ASI2600MC-Pro system and the Celestron 14" Edge HD w/0.7x Reducer and the OGMA AP26CC system. I only worked on the data from the 14" telescope. With the combination of the 14" telescope and the OGMA AP26CC camera, we have settled on 300 sec subs for broadband imaging with the UV/IR cut filter, assuming sky conditions allow for it. If the Moon were up, we would most likely have to reduce exposure time. This target is framed very well with this telescope/camera combination. Here's the resulting processed image:
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| M109 from the BMO on 4/23/2025. |
Processing:
All pre and post processing was performed in PixInsight. Pre-Processing: All light Frames, Flats, Darks and Dark flats were loaded into WBPP. After processing the resulting Master Light Frames, Satellite trails were visible. I blinked the individual subs and found 3 of the 16 subs had very bright satellite trails. I opened the 3 raw frames with the trails and used Seti Astro's Blemish Blaster script to remove the trails. The trails were reduced in intensity but could still be seen. I saved the 3 frames and then re-ran WBPP with more aggressive settings for rejection (reducing the High sigma in Winsorized Sigma Clipping from 3 to 2 and enabling Large Scale Pixel Rejection at a sigma of 2). Linear Post Processing: Background extraction was performed with GraXpert followed by BXT (correct only). SPCC was used for Color Calibration followed by a full application of BXT. The Stars were removed using StarXT. Starless Linear: Noise was reduced with NXT. The image was made non-linear with HT. Starless Non-linear Post Processing: Saturation and intensity were increased with CT. Exponential Transformation was used to increase intensity. The Create HDR Image script was used to compress the core of the galaxies (mask was used). The Image Blend script was used (with high pass filter) to increase sharpness. LHE was applied at two different kernel radii and Unsharp Mask was applied (lightly). Stars Linear: The Stars image was made non-linear with Seti Astro's Star Stretch script. Stars Non-Linear: Saturation was increased with CT. Starless: Intensity, and contrast were adjusted with various applications of CT. The Stars and Starless images were combined with Pixel Math to produce the final image
What is it?
Messier 109 (M109) is a barred spiral galaxy in the constellation Ursa Major. Scientists believe our galaxy, The Milky Way, is a barred spiral galaxy.
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| An annotated version of the M109 image. |
How Big is it?
M109 has a size of 7.5 x 4.4 arcminutes (1 degree is 60 arcminutes) on the night sky. It is about 177,000 light years in diameter.
How Far is it?
M109 is located about 81 million light-years (ly) from Earth.
How to find it?
M109 is located in the constellation Ursa Major as shown by the small red square in the Finder Chart below. The galaxy is located about 40' southeast of Phecda, one of the bowl stars in the big dipper asterism. Dark skies and large aperture are helpful in viewing this galaxy.
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| Finder chart for M109. |
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