Monthly Archives: January 2015

Near Miss Asteroid Chasing

The night of 26 Jan into the morning of 27 Jan presents an opportunity to spot asteroid 2004 BL86, a 0.5km diameter lump of rock destined to pass just 1,191,000 km from Earth. Actually, that’s not really anything to worry about as it’s just over 3x the distance of the Moon!

So, assuming the UK’s skies clear on the night of 26/27 January, what’s the best way to go about spotting the asteroid?

First let’s look at its brightness. As the sky darkens on 26 January, the asteroid will appear as a small dot of magnitude +9.7 – that’s doable with an average pair of binoculars given a clear dark sky but if your visual limit is around mag. +5.0 you’re going to struggle.

As the night, or rather morning, draws on, so the asteroid will brighten. It reaches its peak brightness of mag. +9.0 at 04:30 UT. This is when the asteroid is passing up through Cancer the Crab, heading towards the eastern side of the magnificent binocular object, M44 or the Beehive Cluster. In fact, this object is very useful because it gives you a means to calibrate your binoculars in terms of how deep they can go. Using a pair of binoculars, if you can see stars which are the same brightness or dimmer than the asteroid then you know you’re in with a shot of spotting it. The graphic below shows the Beehive Cluster and identifies the main pattern within it – the bit I always think looks like a beehive, albeit, an upside down one! It should be relatively easy to pick this out with binoculars. Once you’ve done this, jump to the first arrowed pattern and then, once you’re used to the view, see how faint you can go. If you’re not familiar with magnitudes, the larger the number, the fainter the object.

SkyChart III

Assuming you’re able to see stars equal to or dimmer than the asteroid, the next job is to locate it. This is trickier as it’ll appear exactly like a star. However, it’s presence will be given away by the fact that it’ll move noticeably over the space of a few minutes. The downside is that there are a lot of stars around the mag. +9.0 to +10.0 range in that part of Cancer. The chart below gives the location for a given time. The asteroid will be at mag. +9.3 at 00:00 UT on Jan 27 and +9.2 at 01:00, +9.2 at 02:00, +9.1 at 03:00, +9.0 at 04:00, +9.0 at 05:00 and +9.2 at 06:00. At 06:00 the Beehive Cluster will have an altitude of 19 degrees in the west.

2004BL86

The position of the asteroid will vary very slightly with your location due to parallax but the chart below should allow you to find it. This chart doesn’t sugar coat the situation and shows it how it is. The stars picked out go down to mag. +10.0 which means that these are will be slightly fainter than the asteroid.

When trying to locate something like this, identify patterns that stand out to you which lie near to where the asteroid is supposed to be. Use these patterns as your navigational beacons, and use them to home in on the position of 2004 BL86.

Good luck and clear skies!

Update – Here’s a 60s exposure of the field containing the asteroid. 2004 BL86 is shown as a streak in this relatively short exposure.

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A Wobbly View of the Rare Triple Shadow Transit on Jupiter

I returned from an exhausting set of Northern Lights flights on the afternoon of 23 Jan 2015. An early night followed both because I was so tired and also because the weather forecast was favourable for the early hours of 24 Jan. Between 06:23 and 06:58 the planet Jupiter would be crossed by no less than 3 dark moon shadows, cast by the Galilean moons Io, Europa and Callisto. This is an event I’d been looking forward to for some time and had promoted via my writings in the Sky at Night Magazine and also the Star Guide I present on the Sky at Night TV show. Here’s the simulated view at 06:40 UT I created…

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The reason for pushing the event is that this was the last opportunity to see a triple shadow transit until 2032. Such events tend to come in small bursts with up to 3 triple shadow transits occurring within a relatively compact timescale. This batch started with a triple shadow transit which occurred on the morning of 12 October 2013, one for which I was clouded out! The next one occurred when the Sun was still up on 3 June 2014. That one I managed to observe and image through ever thickening cloud despite the bright sky. Consequently the images weren’t amazing but at least I got it! It took a lot of patience though.

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The final triple shadow transit on 24 January 2015 should have been much better but as it turned out it too was rather tricky to view and image. For me the first problem I had was due to fatigue from the Northern Lights flights. I was so tired that I had my doubts as to whether I would actually be able to get up. I set a wake up alarm on my old trusty Blackberry Torch 9800 (I’ve found my iPhone 5’s alarm function to be unreliable and I don’t trust it anymore!) for 04:00 on the 24th and went to bed at 22:00. Before going to bed, my weather apps indicated that rain would pass through the area before the sky cleared. I put my C-14 outside but under cover of my observing cabin’s porch.

Amazingly, I managed to wake up quite naturally at 03:50, before the alarm sounded (how does that happen?!) and headed downstairs. I needed to move the mount for my C-14 across to the east boundary of my garden so I could see the transit which occurred at low altitude in the west. Unfortunately, this meant setting up on a wet lawn. The resulting mud bath at the end of the session was quite impressive! When I went to collect the C-14 from its sheltered location – now properly cooled to match the outside air – I discovered that the rain that fell must have come in sideways across the porch because the scope was wet through.

A quick check inside showed that the main mirror was about 50% dewed up. So I mounted the scope and made the executive decision to remove the corrector plate so I could dry the mirror with a hair dryer. This shows why it’s a good idea to give yourself plenty of time to prepare for events such as this. Of course, the hair drying exercise destabilised the internal temperature of the telescope but there was still time for it to cool properly.

When I finally got a view of Jupiter it was clear that the seeing was pretty awful – some of the worst I’d seen to be honest. Click here to see a video of just how bad it was!┬áThe reason for this was mostly down to a raging northerly jet stream.

I decided to image at prime focus with my ASI 120MM mono high frame rate camera. This still allowed me to see detail but removed some of the nastiness that the poor seeing was pouring down my scope. To make matters worse, the event was due to occur in a location that would position Jupiter above the central heating vent of a neighbour’s house. No matter where I went in my garden, the vent remained in a problem position. It reminded me of a portrait in oils and the way the eyes appear to follow you around the room!

The end result was less than impressive compared to what the C-14 is capable of with this fantastic planet. However, there was a feeling of satisfaction that I’d made the effort and overcome a few unexpected hurdles. In the end, I figured the best way to present the results was to add the 60 separate images I took through a 742nm IR filter (this helps stabilise bad seeing – but there’s a limit!) and animate them together. ┬áHere’s the result (click on the animation to load a larger version)…

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What you’re seeing here are the dark shadows of Io and Callisto off to the right. Look carefully and you might be able to see Io as a slightly brighter dot moving from Callisto’s shadow (the left hand one of the pair). These are joined by two further dark dots on the left of the disc. The upper one is the moon Callisto transiting across Jupiter’s disc – a fairly rare sight in itself. The lower dark spot is the shadow of Europa. The moon Europa can be seen off to the left of Jupiter.

Aurora Flights and Time Shuffling

Every year from November to March I’m employed as an expert guide on a number of aurora expeditions. Most of these don’t land but rather take people to the edge of British airspace in a totally darkened plane to look out in hope of spotting the elusive aurora. The big advantage here is that at a height of 36,000 feet, it’s extremely unusual to get any weather in the way which would otherwise spoil the view.

I’ve been doing this for 10 years, together with a team which works extremely well together. The format of each flight is exactly the same. Passengers gather in a predefined location beforehand in anticipation of a live presentation given by two astronomers, one of which tends to be me. The period before the presentation start time is covered by a multi-media pre-presentation, presentation (PPP) which addresses many of the questions we used to get after each flight. It also introduces the passengers to the team.

I used to write computer software for a living and wrote the scripting language for the PPP. This gives me a lot of flexibility when putting the PPP together. It also allows for problems that sometimes occur when we can’t start the PPP rolling on time. The current version can auto-scale itself to start at any time before the main presentation. Music and graphics always stop at the correct time just before the main, live-presentation. The biggest benefit though, is that I have total control over the PPP’s content and can customised for each flight beforehand. All I need to do is turn up, activate the program and relax – well sort of! The PPP counts down to the start of the main presentations and it’s atomic clock accurate!

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What follows is a brief introduction from an Omega Holidays representative – typically Peter Truman, who initially came up with the idea – and then into the main presentations. Both run for 30 minutes each. The first covers some of the procedures of the flight and a guide to the main patterns of stars that passengers will see outside. The second, describes the aurora; where it comes from, what it looks like and a forecast for our chances of seeing it on the flight.

After this, the next stage is getting on-board the plane. After take off, a short food service normally occurs and then, approximately 40 minutes in, the astronomers attempt to get the cabin as dark as possible. Once this has been done, passengers normally have 20-30 minutes in darkness before we arrive on ‘station’. This is the term used to describe our location, typically between 58 and 61 degrees north, and to the west of the Shetland Islands (out of light pollution range from the islands). Here, the plane takes up an east-west and west-east circuit allowing each side of the aircraft a look towards the north where hopefully the aurora will be putting on a show.

Out of the 250+ flights I’ve now done we’ve not seen any hint of the aurora on just 8 of them. However, in fairness, some of the sightings have been extremely weak displays but the Northern Lights all the same.

The January 2015 season started with a flight from Glasgow Airport. I live on the UK’s south coast and Glasgow is a long drive for me. When we got on board, an operational issue with flight path planning meant we took off 90 minutes late. As it happened this worked to our favour because we got a lovely display of the Northern Lights which we may not have seen had we taken off on time!

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The next night was from Edinburgh which had a weak display. Unusually for us, the following displays from Newcastle, Stansted and Bristol were also rather weak, the Bristol display being virtually non existent! However, the aurora sorted itself out for the last two flights in January from East Midlands Airport and Leeds-Bradford. Both were nail-biters in that the aurora remained misty and indistinct until right up to the last minute when suddenly it burst into life. Fortunately, the Jet2 crews we had on these flights were very understanding and made extra circuits so everyone could get a look. Lots of happy faces leaving the aircraft after those two.

The flights are pretty exhausting to do for the team. In this instance they were arranged as three on (Glasgow, Edinburgh and Newcastle), a one day gap before Stansted and another rest day before the final three (Bristol, East Midlands and Leeds-Bradford). My typically complicated diary meant that the rest day between Stansted and Bristol needed to be be used for my Sky at Night filming duties. I drove straight from Stansted to the Winchester Science Centre, filmed during the afternoon and returned home at 20:30.

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It was clear when I got back so after a bit of internal negotiation between my brain and body, I managed to set up my kit to take some shots of the beautiful comet C/2014 Q2 Lovejoy. Of course, finding the time to process these results is the next hurdle to overcome!

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You can see scheduling information and previous flight photos from my Aurora Flights website.

My last astro image of 2014

What with poor weather and generally poor seeing, it was great to have a restbite on 30 December 2014 and grab some decent results of Jupiter. The conditions for this shot were reasonable but by no means the best I’ve seen from my observing location. A slight northerly component to the wind direction messes up my seeing, air having to pass across land rather than sea, as is the case for me when the wind is from the southeast, south or southwest.

The image is the result of taking a number of movie sequences, sorting and stacking the frames held within each sequence and combining all of these into a final result.

Here, four 90s red filtered mono images were combined with two 90s green filtered images and two 90s blues to produce a final RGB colour result.

As Jupiter is a fast rotator, spinning once on its axis in less than 10 hours, an imaging period of this length would normally result in a blurred RGB. However, using the wonderful WinJupos software it is possible to derotate each result back to a common time.

The net result is a final RGB that looks sharp, detailed and unblurred by Jupiter’s rapid rotation.

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