Object

M81 (NGC 3031) Bode’s Galaxy

Object Information

Image information

Object Type

Galaxy (Spiral) Type Sb

Instrument

LX200GPS 14” OTA @ F5 effective FL≈1778mm

Constellation

Ursa Major

Guiding

SXV / SkyWatcher 80mm achro @ F/6

Magnitude

+6.9

Focal Reducer

Optec NextGen 0.5x

Coordinates

RA 09:55.6 Dec +69:04

Mount

Paramount ME

Size

21 x 10 arc min

Location

Stoney Hills, S.E England

Distance

12 Million Light Years

Acquisition Date

25th - 26th March 2007

Notes

M81 is a bright ‘Grand Design’ galaxy which may be just visible to the naked eye. It is associated with M82, The Cigar Galaxy, which is visually close to. In the recent past, cosmological speaking, M81 and M82 had a close encounter. The larger and more massive M81 retained it’s spiral structure with the arms probably becoming more prominent. M82 was significantly disrupted to form an irregular morphology. This encounter is also probably responsible for the linear features at about a 2 o’clock to 8 o’clock angle to the right of the core in the above image.

M81 was discovered by Johann Elert Bode on December 31, 1774. Pierre Méchain independently found this object in August 1779 and reported his observations to Charles Messier for inclusion in his catalogue.

Capture Device

Starlight-Xpress SXV-H9 Sony ICX285AL Exview HAD Cooled CCD Array 1392 x 1040 @ 6.45uM / Pixel 

Filter Type

Astronomik Type IIc RGB

Colour Technique

LRGB

FOV

≈16.38 x 12.24 arc mins (0.706 arcsec/pixel)

Exposure

231m / 3.85hTotal

Integration

L (39 x 200 sec bin 1x1)

R (12 x 184 sec bin 2x2)

G (11 x 150 sec bin 2x2)

B (11 x 200 sec bin 2x2)

Notes

Sky conditions had a slight ‘milky’ haze. Tracking had occasional 2.5 arc/sec excursions in X and Y with 2 arc/sec per min ramp in Y / 1.5 arc/sec in X axis highlighting a polar misalignment. Temperature compensation factor is off for auto focus control but data has been gained to recalculate this for future use. Some aspects of this image show artefacts from being aggressive with the processing.

This image lacks some of the resolution I’d hoped for. This is due in part to the reasons above but I think my image processing could also be improved. However setting up a scope and a mount is an iterative procedure and I’ve got a lot of data from this imaging run to make improvements.