Messier Galaxies M81 and M82
Uncropped Image
M81 is a large spiral galaxy in Ursa Major that is reasonably local to us at 12 million light years. Its companion, M82 has been disrupted by an encounter with M81 in the past.
M82 is a starburst galaxy with intense star formation triggered by the gravitational influence of M81. The red fan-like filaments at right angles to the axis of the galaxy are formed by a "superwind". The intense star formation has resulted in multiple supernovae explosions occurring about once every 10 years - the explosions power the super wind. The filaments are expanding outwards at about 600 miles a second and glow brightly in hydrogen alpha (red). They are also a very strong source of radio emission, listed as 3C 231 in the 3rd Cambridge catalogue of radio sources.
A very, very faint patch of blue between 3 triangular stars under M81 is Holmberg IX - a small irregular dwarf galaxy under the gravitational influence of M81 - a bit like our Magellanic Clouds.
Technical Card
900/120mm f/7 Skywatcher Esprit 120 triplet refractor.
0.85 x Field corrector with 2 inch IDAS P3 LPS filter
ZWO ASI2600MC; 74 x 300 second subs, Gain 100, Offset 25, Temp = -15c.
EQ6 R mount . EQMOD control.
Pegasus Astro FocusCube 2 electronic focuser.
Session control; SharpCap 4.1 on laptop.
Controlled from inside house with iPAD
Automated plate solving GOTO and focusing. 8 secs at gain 635.
60 dark frames
60 flat frames (electroluminescent panel A, 3500ms exposure @ 0 gain).
Post processed in PixInsight 1.8.9.
Light Pollution and Weather:
SQM (L) =20.3 mpass
Clear throughout.
Polar Alignment:
Using a new William Optics GuideStar 61 to guide this large scope. 360mm focal length.
Error measured by PHD2= 2.6 arc minute.
RA drift - 0.23 arcsec/min
Dec drift - 0.24 arcsec/min
Guiding:
PHD2 guiding with ZWO ASI290mm/WO GuideStar 61.
Every 6th sub dithered.
RA RMS error 0.53 arcsec
Dec RMS error 0.54 arcsec
Astrometry
Resolution ............... 0.900 arcsec/px
Rotation ................. -78.853 deg
Focal distance ........... 861.62 mm
Pixel size ............... 3.76 um
Field of view ............ 1d 33' 43.9" x 1d 2' 38.9"
Image center ............. RA: 9 55 42.256 Dec: +69 21 19.63
Messier Galaxies M81 and M82
Uncropped Image
M81 is a large spiral galaxy in Ursa Major that is reasonably local to us at 12 million light years. Its companion, M82 has been disrupted by an encounter with M81 in the past.
M82 is a starburst galaxy with intense star formation triggered by the gravitational influence of M81. The red fan-like filaments at right angles to the axis of the galaxy are formed by a "superwind". The intense star formation has resulted in multiple supernovae explosions occurring about once every 10 years - the explosions power the super wind. The filaments are expanding outwards at about 600 miles a second and glow brightly in hydrogen alpha (red). They are also a very strong source of radio emission, listed as 3C 231 in the 3rd Cambridge catalogue of radio sources.
A very, very faint patch of blue between 3 triangular stars under M81 is Holmberg IX - a small irregular dwarf galaxy under the gravitational influence of M81 - a bit like our Magellanic Clouds.
Technical Card
900/120mm f/7 Skywatcher Esprit 120 triplet refractor.
0.85 x Field corrector with 2 inch IDAS P3 LPS filter
ZWO ASI2600MC; 74 x 300 second subs, Gain 100, Offset 25, Temp = -15c.
EQ6 R mount . EQMOD control.
Pegasus Astro FocusCube 2 electronic focuser.
Session control; SharpCap 4.1 on laptop.
Controlled from inside house with iPAD
Automated plate solving GOTO and focusing. 8 secs at gain 635.
60 dark frames
60 flat frames (electroluminescent panel A, 3500ms exposure @ 0 gain).
Post processed in PixInsight 1.8.9.
Light Pollution and Weather:
SQM (L) =20.3 mpass
Clear throughout.
Polar Alignment:
Using a new William Optics GuideStar 61 to guide this large scope. 360mm focal length.
Error measured by PHD2= 2.6 arc minute.
RA drift - 0.23 arcsec/min
Dec drift - 0.24 arcsec/min
Guiding:
PHD2 guiding with ZWO ASI290mm/WO GuideStar 61.
Every 6th sub dithered.
RA RMS error 0.53 arcsec
Dec RMS error 0.54 arcsec
Astrometry
Resolution ............... 0.900 arcsec/px
Rotation ................. -78.853 deg
Focal distance ........... 861.62 mm
Pixel size ............... 3.76 um
Field of view ............ 1d 33' 43.9" x 1d 2' 38.9"
Image center ............. RA: 9 55 42.256 Dec: +69 21 19.63