M81 Bodes Galaxy & M82 Cigar Galaxy

M81 Bodes Galaxy & M82 Cigar Galaxy; Captured at HCH, Colorado Springs, CO with ASI2400-BZ-LeX on 2 April 2023

Fun facts

Messier 81 (also known as NGC 3031 or Bode’s Galaxy) is a grand design spiral galaxy about 12 million light-years away in the constellation Ursa Major. It has a D25 isophotal diameter of 29.44 kiloparsecs (96,000 light-years).  Messier 81 was first discovered by Johann Elert Bode on 31 December 1774. Thus, it is sometimes referred to as “Bode’s Galaxy”.  In 1779, Pierre Méchain and Charles Messier reidentified Bode’s object, hence listed it in the Messier Catalogue.

Messier 82 (also known as NGC 3034, Cigar Galaxy or M82) is a starburst galaxy approximately 12 million light-years away in the constellation Ursa Major. It is the second-largest member of the M81 Group, with the D25 isophotal diameter of 12.52 kiloparsecs (40,800 light-years). It is about five times more luminous than the Milky Way and its central region is about one hundred times more luminous. The starburst activity is thought to have been triggered by interaction with neighboring galaxy M81. As one of the closest starburst galaxies to Earth, M82 is the prototypical example of this galaxy type. SN 2014J, a type Ia supernova, was discovered in the galaxy on 21 January 2014. In 2014, in studying M82, scientists discovered the brightest pulsar yet known, designated M82 X-2.

M82, with M81, was discovered by Johann Elert Bode in 1774; he described it as a “nebulous patch”, this one about 3⁄4 degree away from the other, “very pale and of elongated shape”. In 1779, Pierre Méchain independently rediscovered both objects and reported them to Charles Messier, who added them to his catalog.

Other Catalog Designations: M81, NGC3031, Bode’s Nebula, The Great Spiral; M82, NGC3034, Ursa Major A
Subtype: Spiral Galaxy (Bode’s)
Distance from Earth: 12 million light years
Diameter: 96,000 light years (M81); 40,800 light years (M82)
Visual Magnitude: 6.94 (M81); 8.41 (M82)
Constellation: Ursa Major

{From: https://en.wikipedia.org/wiki/Messier_81 and https://en.wikipedia.org/wiki/Messier_82 & Stellarium}


Polar alignment: QHYCCD camera (controlled by Polemaster)
Imaging stream: Orion 10″ f/8 Ritchey-Chretien Astrograph Telescope, ZWO ASI2400MC imaging camera with Optolong L-eXtreme 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, I decided to image M81 and M82 all night long. For whatever reason, struggled with the plate solving. The framing tool had the camera angle at 72 degrees – SGP got into the rotate x degrees clockwise, rotate y degrees counterclockwise then failing to plate solve. Went through several troubleshooting steps: reboot the laptop, release locks and manually recenter RA and Dec, rotate the camera starting from known zero to 72 degrees, rebuild the target in SGP framing tool with a larger FOV, cycled power on mount. Finally, after more than 1:30 hours of trying, finally successfully plate solved and calibrated the auto-guider and captured the first 5-minute exposure. Determined that exposure time wasn’t long enough, so updated the sequence to capture 10 minute exposures (let the second 5-minute complete). In looking at the 5 minute exposures, it appeared that the stars were somewhat oblong, so I decided that the focusing might have been affected by all the rotating the camera and decided that I should refocus – which required terminating the sequence, executing the focus star (Dubhe) sequence (the focus was fine) and then reacquiring M81/M82. The plate solving took another 30 minutes of fiddling. All this in time to capture two 10-minute exposures before the meridian flip! Same issues with plate solving encountered after the meridian flip, although it only took about 20 minutes to resolve. Began capturing after the meridian flip at 2231MDT, intending to capture until the end of astronomical twilight (beginning of nautical twilight) at 0545MDT. As I periodically woke up throughout the night, I would take a look outside – the wind was picking up – but not to disturbing levels and the mount was still tracking. …until I woke up at 0200 to find the sequence had aborted due to a lost guide star (capturing the last frame ending at 0134MDT). The clouds were pretty pervasive and the wind was picking up – so decided to end the sequence at that point, capture flat frames and bring the equipment in for the night.
Sequence plan: Gain: 158, Temp: -0°C, offset=30. BZ LeX 2x5min, 21x10min. Captured 2Apr2023, 2108MDT – 3Apr2023, 0134MDT. Total exposure time: 3:40hrs
Capture: 2 April 2023
Shooting location: Colorado Springs, Colorado
Processing: Stacked in APP, processed in LR/PS.