Observation by John Hughes: Messier 81 and Companions
Uploaded by
Paul Downing, FRAS
Observer
John Hughes
Observed
2020 Mar 12 - 23:00
Uploaded
2020 Apr 11 - 12:03
Objects
M81
Planetarium overlay
Constellation
Ursa Major
Field centre
RA: 09h57m
Dec: +69°12'
Position angle: -4°10'
Field size
1°40' × 1°15'
Equipment
- William Optics Z103 APO Refractor
- ZWO ASI1600mm Pro Cool camera
- William Optics 50mm Guidescope
- ZWO ASI290mm mini Guide Camera
Exposure
L 19 x 120s & 98 x 60s Bin 1x1 R 10 x 60s Bin 2x2 G 10 x 60s Bin 2x2 B 15 x 60s Bin 2x2 Ha 46 x 300s Bin 1x1
Location
North Essex, UK
Target name
Messier 81
Title
Messier 81 and Companions
About this image
John reports having some issues with artefacts and also as this was his first attempt at combining LHaRGB the calibration of the lights with flats, darks and dark flats was a challenge. Warren A. Keller, author of Inside PixInsight was very helpful in an earlier question John put out to the PixInsight for Beginners Group on FaceBook and cleared up his confusion over calibration.
Ron Brecher's presentation on The Astro Imaging Channel on YouTube helped with a dust mote that wasn’t entirely cleared by John's master flat (Pixel Math section “if the pixels are this, do this, or do nothing”). Using this method helped him to slightly raise the brightness of pixels in the offending area leaving the rest of the image untouched.
The artefact? Well, as hard as he tried he couldn’t remove a lightish smudge to the left of Messier 81, but checking on the Astrobin website revealed that it was actually galaxy PGC28757!
John reports that this was a very challenging project, using five filters and the additional complication of imaging across multiple nights, but was well worth the time put in.
Files associated with this observation
Like this image
