M81 and M82

I have become a bit of a comet addict in my astrophotography, and with so few opportunities to take advantage of clear skies in Cumbria, have neglected my other targets in favour of these elusive and challenging subjects.  Yesterday evening I determined to spend time away from comets and catch myself a couple of galaxies.

M81 and M82, 12 million light years away in Ursa Major, were at good altitude mid-evening, rotating toward the zenith.   The birthday fairy brought me a QHY5L-II CCD camera last month, which I can use for guiding my Altair Wave 115/805 on the Skywatcher AZ-EQ6 mount.  Ten-minute subframes was my choice of exposure for the session.  I suspect these might be achievable unguided, now that the mount is sorted, but I wanted to test the setup and familiarise myself with all that it requires.  Humidity was high and the sky was lighter than I remembered at Old Hutton church carpark, so I kept the Nikon D90 at a low ISO of 400 for the long exposures.

Focusing was manual using a Bahtinov mask.  Five frames came out well, one jumped during the guiding and was discarded.   The full PixInsight processing sequence from Nikon RAW files was:

Convert to FITS

Calibrate (not this time though, I took neither dark nor flat frames!)

Debayer

Register (align)

Stack to average, using percentile rejection

Dynamic Background Extraction (eliminate the skyglow)

Colour Calibration (no more green-tinted pictures!)

Histogram Stretch

Saturation and background darkening using Curves

Noise Reduction

High Dynamic Range Multiscale Transformation (detail in the spiral arms)

Crop and convert to JPEG.

 

This is the full size JPEG after processing.  I should get out more!

M82 and M81 Nikon D90 on Altair Wave 115/805 (f/7), ISO 400 50 minutes: 5 frames of 10 minutes each.

M82 and M81
Nikon D90 on Altair Wave 115/805 (f/7), ISO 400
50 minutes: 5 frames of 10 minutes each.

Here’s another version with some sharpening applied too.  I separated the luminance data from the colour data, sharpened the luminance and blurred the colour before recombining.  It’s a mixed result, definitely bringing out more detail but also I think it gives a slightly artificial edge to the galaxy.  More practice needed…

M82 and M81 Nikon D90 on Altair Wave 115/805 (f/7), ISO 400 50 minutes: 5 frames of 10 minutes each.

M82 and M81
Nikon D90 on Altair Wave 115/805 (f/7), ISO 400
50 minutes: 5 frames of 10 minutes each.

 

Our turn at last!

The recent weather patterns have tested the patience of many observers and astrophotographers in the UK, but on the night of 18 January, it was most definitely our turn for clear skies.  I drove to the church car park at Old Hutton at around half past five, to find three colleagues from the Eddington Astronomical Society already there!

There were three potential comet targets on my list that evening, resulting in varying levels of success and more lessons learned.

The handset of my AZ-EQ6 mount allows pre-programming of GOTO coordinates, so I had already loaded the comets’ coordinates in the warmth and comfort of home.  Once the mount was aligned, picking up the pre-programmed targets was very easy.  I also took the opportunity of the observing delay (caused by the slight cloud layer during the alignment process) to calibrate the mount’s adjustment knobs.

First up, low in the south west, Comet 15P/Finlay which is described in Sky Safari as magnitude +13, but is unexpectedly in “outburst” so significantly brighter.  I could see it clearly in the 24mm eyepiece at 33x magnification.  In the photo, its outburst form is very clear and really rather pretty.

Comet 15P/Finlay Nikon D90, Altair Wave 115/805 ISO 800, 6x3min.

Comet 15P/Finlay
Nikon D90, Altair Wave 115/805
ISO 800, 6x3min.

Finlay had to be the first target as it was only 15° above the horizon at dusk, and quickly setting.

Then on to Lovejoy, which was visible to the naked eye and also very strong through the telescope.  I had already attached the camera in place of the eyepiece on mine, so I got on with taking pictures.  This is Lovejoy on the same scale as Finlay:

Comet C/2014 Q2 (Lovejoy) Nikon D90 on Altair Wave 115/805 ISO 800, 13x3min.

Comet C/2014 Q2 (Lovejoy)
Nikon D90 on Altair Wave 115/805
ISO 800, 9x3min.

Switching to the 300mm telephoto catches more of the tail:

Comet C/2014 Q2 (Lovejoy) Nikon D90 and Nikkor 300mm ISO 800, 9x3min.

Comet C/2014 Q2 (Lovejoy)
Nikon D90 and Nikkor 300mm
ISO 800, 9x3min.

And finally a wide angle “context” shot through the trusty old 50mm manual lens (which came with my first Nikon, the F301, in about 1987).  The tail goes on for ever, past The Pleiades and the head of Taurus.

Comet C/2014 Q2 (Lovejoy) Nikon D90 and Nikkor 50mm ISO 800, 7x5min.

Comet C/2014 Q2 (Lovejoy)
Nikon D90 and Nikkor 50mm
ISO 800, 7x5min.

All in all, a very satisfying evening.

What about the third target?  More of that later…