Lunar eclipse 28 September 2015

Torn between astrophotography and sleep for this one!  Our walking holiday on the Amalfi coast had finished on Saturday with a beautifully long slow lunch among friends on the terrace at Leonardo’s in San Lazzaro, and our late flight out of Naples finally put us down at Gatwick at about 11.30pm.  Overnight hotel at the airport, train journey to have lunch with my mother-in-law (where we had left the car) then a five-hour drive home to Cumbria.  We arrived home in the early evening on Sunday, ready to drop.

The Moon was set to move into the Earth’s full shadow at about 2.15 Monday morning, so I set the alarm for 1.30, as you do.  The forecast was good, it had been improving steadily over the last couple of days, and I guessed that if I woke up and looked out just before the start of the action I would be able to decide whether it was worth setting up a session.

1.30 brought glorious clear sky and an added bonus: the Moon’s position meant that I could catch at least a couple of hours from my own back yard.  That was the deciding factor – just the trusty DSLR on a tripod with the 300mm telephoto lens.  This was the view at the start, reproduced actual size in the viewfinder:

2.06am. The shadow is just visible.
Nikon D90 through Nikkor Nikon 300mm f/4 AF.
1/1250 sec f/8, ISO 800.

I decided to take one shot every 30 seconds, with the intention of stitching them together as a time-lapse video.  Of course the Moon drifted fairly quickly across the frame so the tripod had to be adjusted every few shots.

2.45am: 40 minutes into shadow.

By the time the Moon was about to disappear behind the house, it was in full eclipse.

3.12am: exposure increased to see the illumination in full eclipse.
1 sec @f/5.6, ISO 1000.

Noticeably very red to the naked eye – and the camera – it was somewhat of a disappointment in binoculars as the brightness dropped so significantly.  This could be because the Moon was almost at perigee (the so-called “supermoon”), closer to the Earth than normal and therefore deeper into the cone of the Earth’s shadow.  The air went a little murky too, so the final shots lost some definition.

Each frame had to be cropped and realigned to make the video run smoothly.  Stitched together and reduced from 4288 x 2848 to 1000 x 1000 pixels, these make a reasonable time-lapse.

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.

Dark skies and new standards

On 18 April, I drove out to a new location near Tebay to the east of Kendal, in search of higher altitude and darker skies.  I had been keen to try this spot for some time, and conditions were just right.  With reasonable elevation above sea level, and hills providing shelter from the lights of the only nearby town, it was as good as expected.

My first objective was the comet C/2012 K1 (PANSTARRS) which has been exciting the astronomy community.  I have been very keen to get the new kit up and running in order to join the amateur and professional astronomers contributing observations, photographs and measurement data for this comet.

I could not be more pleased with this, my first serious contribution.  You can see that I have added a Photoshop layer of information, showing the angular scale of the capture and various technical details.  This and others in the same vein will be part of my regular submissions to CIOC, the NASA-sponsored collaboration between professional and amateur astronomers which has evolved from the earlier collaboration prompted by observations of Comet ISON.

Once the comet is in the bag, I have to catch another target to exercise my processing skills.  This time I choose a globular cluster in the constellation of Hercules, catalogued as M13.  This cluster measures about 145 light years across, is about 25,000 light years away, and contains hundreds of thousands of stars.

18 April 2014: Globular cluster M13 (Mag 5.8) from Tebay Road.
Altair Wave 115/805, ISO 1250, 8 minutes.
16 frames of 30 seconds.

I had known there would only be a short gap between the end of dusk (where the Sun is 18º below the horizon) at 22:47 and Moonrise at 00:12 and, sure enough, about half an hour later the Moon hoves into view over the hills in the East and brings the session to a close.

The Moon rises and brings activities to a close shortly after midnight.
Nikon 300mm f/8, ISO 1250, 1/125 sec.

Crescent Moonset

On Tuesday evening 1 April the forecast looked pretty good.  As I packed the car in an optimistic mood for another go at the constellation of Leo, I glanced towards the west and saw the thin crescent Moon about 90 minutes from the horizon.  All plans changed, and I headed out to Helsington church, south-west of Kendal, with good views to the hills of the Lake District on the western horizon.

The Moon looked okay through the new combination of Nikon D90 and Altair Wave 115/805 ED Triplet (hereafter “my telescope”), but only okay.  The humidity was higher than expected, as was the wind speed, and the atmosphere low to the horizon was not going to cooperate.

This was about the best on offer:

805mm f/7, ISO 800 1/30 sec

Of course this location and composition are one of my favourite combinations, so I switched to the 300mm lens as the Moon approached the horizon.  ISO 800 with the lens wide open at f/4, this is the series of 30-second exposures as the Moon set behind the skyline of the National Park:

I stopped the mount motor to take one frame with the horizon stationary, which shows how much the Moon was moving over the 30 seconds:

Clipping that horizon in Photoshop, I can use it to take the blur out of the earlier shots. I’ll leave it to you to decide whether this is an improvement.

Moon and Saturn

The chart said these would be due south at 3.30am on 21 March, elevated 18° above the horizon.  A quick check the previous evening showed that the gap between the tree and the neighbour’s house, viewed across the top of my shed, would just give me an unobstructed view.

I was still awake at 1am, kept getting up to see whether the clouds had cleared, and was surprised when the alarm woke me at 3.00.  I opened the west-facing bedroom window to stick my head out, and saw clear sky to the south – with the Moon exactly as predicted.

Set up the tripod, mount the new Altair Wave 115 – with the Nikon attached as if to an 805mm f/7 lens.  After years of SLR photography, I still think in terms of focal length rather than objective lens diameter.  The field of view with this combination is 1.68° x 1.12°, perfect for this shot as Saturn was just 1.2° from the Moon.

Focusing was very easy with the Bahtinov mask and the dual speed focuser, especially with the Nikon’s LiveView screen zoomed right in on Saturn.  Even though Saturn is a ringed disk rather than a point of light, the changing shape of the view through the mask was obvious.

At ISO 400, trial and error gave 1/250th of a second exposure for the Moon, and 1/30th for Saturn.  By 4am I was quickly layering these together in Photoshop…

The Moon and Saturn separated by one degree
805mm f/7 ISO 400 1/250 sec (Moon) 1/30 sec (Saturn)

…and back in bed at 4.15, just as the clouds returned.

Stitching!

I now write a regular piece for the Eddington Astronomical Society, setting out what’s going to be on view in the night sky each month. In all honesty, it will probably lean towards astrophotography!  You can see the March 2014 version here.

One of the opportunities identified as coming up in March was the view of Jupiter reaching its highest point in the sky, elevated 59° in the early evening of the 13th. This looked like a challenging photo project, with bright Moon, bright Jupiter, bright and faint stars and the inevitable Morecambe Bay glow. It would also be at its best during twilight.

Sadly the Cumbrian rain was forecast for that evening, but we enjoyed a few days of high pressure just before then, with a couple of clear nights.

On Tuesday, 11th March, I strolled up to the Mushroom on Scout Scar with no more than camera and tripod. The 18-200mm zoom is pretty wide at 18mm, but I wanted a field of view of about 150°, so I set it to 24° and took nearly forty frames in a grid pattern looking south.

Photoshop can stitch shots together to make panoramas, but it needs clear points of reference in the shots and can only run on automatic. So, if it can’t identify the overlapping shots itself, there is no option for user-intervention. It simply doesn’t work on night sky mosaics.

That’s when I found PTGui, a programme that does exactly the same, but with a much wider range of projection options and, most importantly, the facility for the user to identify the overlap points (ie the stars) manually.

Here is the result, the view south from Scout Scar, Tuesday evening13th March. The sky isn’t flat, of course, and stitching frames requires distortion according to various rules depending on the projection settings. Circular projection seems to give the best compromise on distortion, then I cropped the result to a nice tidy rectangle.

All frames ISO 1600, 10 seconds 24mm f/5.6.

Big sky! Nearly 40 frames each 10 sec ISO 1600, 24mm f/5.6, stitched in PTGui