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.

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, 9x3min.

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

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.

All in all, a very satisfying evening.

What about the third target?  More of that later…

Encounter with Lovejoy

Images have been pouring in from around the world of this most photogenic comet, which is already around 4th magnitude and visible in the night sky of the northern hemisphere.  After many frustrating evenings of cloud hopping, or being completely defeated by the inclement weather,  or having the comet’s delicate tail features drowned out by a full Moon, our turn came round on Monday the 12th of January.

The normal best options of Tebay Road and Shap Summit were forecasting winds gusting to 30 and 40 mph, and looked as though they would be clouded over earlier than more northerly locations.  Keswick, in the north of the Lake District, showed great promise on the forecast charts – and there is a beautiful location above the town which is home to the Castlerigg Stone Circle.  The forecast here was for gentle breeze and cloudless skies from twilight to about 9pm.

After about an hour’s drive it was pedestrian access only, through a narrow gate on a strong spring, so it took several trips from the parked car to set up the tripod, mount, telescope, camera and all the bits and bobs that make up an astrophotography session.  The sky looked clear as the light faded, and Lovejoy was clearly visible to the naked eye before full darkness at 18:36.

The new alignment routine for the mount was really straightforward, and the handset reported alignment to within ten arc minutes in altitude and azimuth.  That’s enough for the exposure needed, so I hooked up the camera and started.

First off, a series of frames through the 300mm lens, which stacked nicely to reveal some good detail in the comet’s tail.

Comet C/2014 Q2 (Lovejoy), 12 January 2015
Nikkor 300mm f/5.6, ISO 800, 22 minutes.
22 frames of 1 minute.

To be really critical, there are some major defects in this photo.  The ambient light from the nearby town caught the humidity in the air and presented a layer of faint light – invisible to the eye – that blurred in the wind across the long exposures.   It can be seen as a scratchy effect right across this photo.  I last saw this phenomenon when I took summer photos of Comet C/2011 L4 (PANSTARRS) passing Yildun from my back yard in June 2013.  At the time I thought this might be a combination of light, moisture and wind, and now I’m sure of it.  This defect also made replacement of the stars – eliminated by the comet processing – less satisfactory.

By the time I have collected enough of these frames the clouds are creeping in, so I switch to using the Nikon straight through the telescope, effectively an 805mm lens.  Some of the effect of the ambient light is eliminated by this move, but the result is still less than totally satisfying.  Several of the frames had to be discarded as they were degraded by cloud interference.

Comet C/2014 Q2 (Lovejoy), 12 January 2015
Altair Wave 115/805 f/7, ISO 800, 16 minutes.
16 frames of 1 minute.

It is interesting to think that a couple of years ago, I would have been blown away by the thought that I could take photos like these.  Now, with greater experience and understanding of the techniques, I cannot help but see the imperfections.  That falls somewhere between a disappointment and a really exciting challenge!

Some you win…

Not sure if this constitutes a win or a loss, on balance.  It was a rare clear night on Saturday, after the weather system of the last week had passed, and it left in its wake a crystal clear arctic air mass with low humidity – low for Cumbria, that is, of which more later.

I took the gear up to the Shap Road lay-by and set about capturing comet C/2014 Q2 (Lovejoy).  Once the mount was aligned, I dialled in the location of the comet, listened to the wheels and belts of the mount humming away and heard the handset beep to indicate the comet was in the viewfinder.

The 300mm lens was already attached to the telescope so I took a sequence of shots using this setup first.  The light level of the full Moon was ridiculous, and Lovejoy was only 30º from the Moon.   No trouble seeing the comet, of course, but I know there is a subtle tail streaking across the field of view and I wanted to catch it.

Stacking and processing was immensely trying.  The tail is there, but it is so completely lost in the moonlight scattering off the moisture in the air that it is an impossible task to isolate it.  The more I stretch the processing of these images, the more frustrating it becomes.

300mm telephoto lens
ISO 800, 70 x 20sec exposures

Against a dark sky, this would be a stunning shot.  In the “low” Cumbrian humidity of around 80%,  catching the moonlight and spreading it across the frame, it is a nightmare.

Through the telescope at 805mm focal length, it’s the same story.

Comet C/2014 Q2 (Lovejoy)
Nikon D90 on Altair Wave 115/805 ISO 800, 100 x 20sec

There’s a wonderful hint of comet tails here, but they are drowned in moonlight.

Maybe I should have stuck to the “context shot”, the wide angle image that shows the brightness of the sky and the fuzzy blob of the comet.  Oh well, we get what we get, and live to get some more next time.

For those that like the Moon (and yes that includes me!) here it is from that night.  I’ve toned it down a little, to show some surface detail and the tiny crescent of shadow on the edge that indicates it’s not quite full.  Once it’s safely out of the way in about a week, I’ll be back for more comet action.