M106 Hunting Dog Galaxy

M106 Hunting Dog Galaxy; Captured at HCH, Colorado Springs, CO; with ASI2400 BZ LPro on 15 April 2023

Fun facts

Messier 106 (also known as NGC 4258) is an intermediate spiral galaxy in the constellation Canes Venatici. It was discovered by Pierre Méchain in 1781. My main target was M106, what I’m calling the Hunting Dog Galaxy.  That’s not its official name, it’s just referred to as the “galaxy in Cane Venatici.”  The constellation is visible between the constellations of Boötes and Ursa Major and that is represented by the figures of dogs.  The dogs of Canes Venatici are usually pictured as being held on a leash by the figure of Boötes the Herdsman, the figure associated with the constellation Boötes. Venaticus is Latin from vēnāticus (feminine vēnātica, neuter vēnāticum) meaning of hunting, especially canis venaticus “hunting dog.”  So…a small lesson on constellation lure and Latin lesson thrown in…no charge ;-}  

M106 is the “large” galaxy (at a distance of about 22 to 25 million light-years away from Earth). It is one of the largest and brightest nearby galaxies, similar in size and luminosity to the Andromeda Galaxy.  Its size is 135,000 light years (in diameter), with an apparent size from earth of 18′.6 × 7′.  M106 contains an active nucleus classified as a Type 2 Seyfert, and the presence of a central supermassive black hole has been demonstrated from radio-wavelength observations of the rotation of a disk of molecular gas orbiting within the inner light-year around the black hole. 

NGC 4217 is a possible companion galaxy of M106 – seen in the bottom right of the frame in an edge-on perspective – looking a little bit like the Sombrero Galaxy.  The other galaxies “nearby” are: NGC4226, NGC4231, NGC4232, and NGC 4248

Stellarium screenshot with M106 FOV indicated, showing the other galaxies in the FOV and image

M106 has also played an important role in calibrating the cosmic distance ladder. Before, Cepheid variables from other galaxies could not be used to measure distances since they cover ranges of metallicities different from the Milky Way’s. M106 contains Cepheid variables similar to both the metallicities of the Milky Way and other galaxies’ Cepheids. By measuring the distance of the Cepheids with metallicities similar to our galaxy, astronomers are able to recalibrate the other Cepheids with different metallicities, a key fundamental step in improving quantification of distances to other galaxies in the universe.

{From: https://en.wikipedia.org/wiki/Messier_106}

Other Catalog Designations: M106, NGC4258
Subtype: Spiral Galaxy
Distance from Earth: 25 million light years
Diameter: 135,000 light years
Visual Magnitude: 8.41
Constellation: Canes Venetaci


Polar alignment: QHYCCD camera (controlled by Polemaster)
Imaging stream: Orion 10″ f/8 Ritchey-Chretien Astrograph Telescope, ZWO ASI2400MC imaging camera with Optolong L-Pro LP filter.
Mount: Sky-Watcher EQ6-R Pro Equatorial Mount (controlled by EQMOD)
Autoguider: Orion 60mm Multi-Use Guide Scope, Orion StarShoot AutoGuider Pro Mono Astrophotography Camera (controlled by PHD2)
All equipment controlled by HP Probook running Sequence Generator Pro v3.2.0.660.

Capture & processing notes

Projected to have calm winds and clear skies all night long, with the moon not rising until 0447MDT. Decided to image M106, a galaxy in Canes Venetaci that doesn’t have a name, but I call it the Hunting Dog Galaxy. All the pre-sequence activities went well – polar alignment only required a slight adjustment, focus star (Cor Corali) was almost in focus from the start, the plate solving worked after three attempts, and autoguider calibrated the first time. So, within 30 minutes from when I got out of bed from the pre-imaging nap I captured my first image. I had the alarm set for the meridian flip at 2340MDT. When I went out to do that, I discovered that the laptop had shutdown. I cursed at the laptop, then got about the business of putting the mount back to its home position manually (apparently it had continued to track even though the laptop was not controlling it). Got the sequence going again at 2357MDT. I woke up and went out to check it at about 0130 and all was well. Then when I woke up again at about 0230, thinking I’m sure it’s fine, but I better check – it had shut down again. ARGH. More cursing and again manually returning the mount to home, cycling the power, and restarting the sequence. This time it continued until the end of the night – actually capturing two images after the start of nautical twilight that were culled out for having too much light. (Need to plan to stop sequences at beginning of nautical twilight, end of astronomical twilight.
Sequence plan: Gain: 158, Temp: -0°C, offset=30. BZ LPro 68 x 5minute. Captured 15Apr2023 2059-2201MDT (laptop shutdown), 15Apr 2023 2357MDT – 16Apr2023 0207MDT (laptop shutdown) and 16Apr2023 0248 – 0529MDT. Total exposure time: 5:40hrs
Capture: 15 April 2023
Shooting location: Colorado Springs, Colorado
Processing: Stacked in APP, processed in LR/PS.