Sunspots (3/7/23)

 

The Sun's Active Regions (22/6/23)

At Time of Increasing Solar Activity

Here are today's active solar regions (A.R.'s) showing more sunspots than I'ver captured before.  Although the sun emits all wavelengths of light and these combine to make white light, people are used to seeing the sun with an orange colour (caused by the scattering of all the shorter wavelengths but the atmosphere) and so I have increased the white balance to make it appear orange rather than the normal white colour my solar filter produces.

Here are some closer versions of the main sunspot groups being seen today:

A.R. 3163, A.R. 3166 and A.R. 3162

A,R. 3167 and A.R. 3160

A.R. 3165

A.R. 3168

A.R. 3163

A.R. 3166 and 3162

Sunspot AR 2822

 

Set the Controls for the Heart of the Sun

Today I have been mainly photographing an International Space Station's Solar Transit.  This is when the ISS passes across the face of the sun creating a silhouette of its shape.  Whether you can view a solar transit like this depends on where you are on earth at the time of its passing.  Luckily, today it was viewable from some parts of the UK.

To view a transit you need to plan in terms of location and time, prepare your equipment and execute your plan at exactly the right time.  Finding out where it will be viewable is quite easy nowadays using online resources. I use ISS Transit Finder to look out for and plan solar and lunar transits by the ISS. Here is an outline of the procedure:

Planning

1. Go to transitfinder.com
2. Enter your location by using 'Auto-detect' or by entering your latitude and longitude co-ordinates
3. Enter the dates in which you are interested - you can only go up to 30 days in advance
4. Enter how far you would be willing to travel in km (100 is good number to choose)
5. Click the 'Calculate' button.

This will take you to a screen that shows you the next solar and lunar transits which can be viewed from or near your location, in date order.

From the above image it can be seen that when I was planning this, the next solar transit was 2020-12-05 (US date format) which is today. However, the quality of view was only going to be 2 star from where I live in Tyldesley with only 1.21 seconds of viewing time and the ISS is only just skirting the bottom of the sun. Clicking on the 'MORE INFORMATION' button revealed more detail:

Clicking on 'SHOW ON MAP' produces a map of the transit path showing my location as a red pin and an ideal location on the line of maximum viewing time with a green pin.

Anywhere along the central line would give a viewing of 2.37 seconds.  So I closed the pop up box and zoomed into the map to find a good spot.  It was at this point that my friend Paul Richardson suggested Dunham Massey, as it's an area not far from our homes and almost exactly on the central line.  He suggested a free car park on Henshaw Lane, but when I actually got there it wasn't in the best position. However, I soon found another spot just 100 metres up the road and Paul joined me there.

Preparation

The preparation to get an image of the solar transit mainly requires a lot of thought.  There are two main methods I considered:

1. Fire a rapid burst at exactly the right time
2. Take some video of the passing

Having two DSLR cameras, I decided to try both methods.

The first method depends on having the right camera settings and firing a burst exactly on time. Luckily, I've imaged the sun a few times now, the first time being capturing the Transit of Mercury back in November 2019 - you can read about that here.  So I had an idea about the settings, although clouds can sometimes play havoc with what you think should be correct.  I set the camera to fully manual mode, and used ISO 100, an aperture of f/9 and a shutter speed of 1/1000th of second and practised in my back garden.

The second method doesn't require exact timing as the video can be started early and left running.  Although you will be sure of capturing it that way, the resulting images may not be as sharp for such a small, fast moving object. A high frame rate and fast shutter speed would be needed.

To help with timing, I downloaded an accurate time app for my phone called 'Atomic Clock' which is synced to internet time and which gives the time in milliseconds.  My shutter release cable and two home-made solar filters made for the Mercury Transit were also needed. The shutter release cable helps avoid unwanted vibrations often caused by touching the camera. 

The solar filters are essential for viewing the sun to avoid damaging your eyes and the camera sensor.  You can read how I made mine here. I never look at the sun though the eyepiece, only on the back screen of the camera.  It also helps to use a towel or sheet placed over the camera and your head when viewing the camera screen, to cut out unwanted light from the sun.

I decided I'd set up two cameras on tripods each with a solar filter (one for video and one for stills) to ensure I got some record of the transit.  I'd start the video recording early and leave it running, then concentrating only on the stills camera which I would fire a three second burst activated by the shutter release cable.  My camera, a Nikon D500, has a large RAW file buffer and can shoot up to 200 continuous frames at 10 frames per second, although there is somethings a brief pause after 50 frames. I used a 500mm f/4 lens with a 2x teleconverter to give 1000mm (or 1500mm in 35mm terms).

Because the ISS was only going to be a tiny silhouette against the very bright sun, I decided that the shot I wanted was a composite of its path across the face of the sun. A single image like the one below isn't all that interesting. So all I'd need to do was hold the shutter down firing rapidly as it passed by - easier said than done and only one go at it!

Execution

Having done the preparation, the final part was to put the plan into action. I arrived early to cope with setting everything up correctly and doing a few test exposures. Paul turned up shortly afterwards and when we were both ready we just had to wait for the right time. Paul was shooting video though an 400mm scope with a 2xBarlow and a DSLR camera.

Anxiously checking the Atomic Clock app, I called out the time every now and then waiting for 13:16, at which point I held down my shutter release and fired away.  I carried on doing it for three button presses which took about 200 shots each until 13:17 arrived, at which point I knew it the ISS had gone. 

 

Before we knew it, it was all over.  We quickly checked the backs of our cameras but neither of us could see anything except the sun.  I thought I'd blown it. I'd have to wait until I got home to find out that I'd actually captured it!  I sent a text to Paul to tell him I had and that he should have something too.  He later confirmed that he had. Below is an animated GIF which I made from the individual frames.

Unfortunately, my video recording was very underwhelming as expected.  Having used my best equipment on the stills, I had to use a full frame camera on a 300mm lens plus a 1.7x teleconverter for the video.  Although I have captured something, it just wasn't long though to record the tiny ISS in any detail.

Processing

The final part of this little project was to produce a final image of the ISS transit shown below.  This was done by importing the images into PhotoShop via a script which loads them into an image stack, with many layers. Each layer was a different shot.  Although I selected 'attempt to align images in stack' when importing them, my first attempt at combining them using the Darken blend mode resulted in the sunspots being elongated as the sun tracked from left to right.  Funnily enough, the sun still looked round, but the sunspots looked awful.  I tried fudging it by cloning some of them out of the image, but it really didn't look good.

So I then had to painstakingly align each image manually, which I did by creating several ruler guide lines on the spots, before cropping and doing some final colour and sharpening edits.  This is the final image and I have to say I'm quite pleased with it.

Isn't it nice when a plan comes together?

PLEASE REMEMBER THAT YOU SHOULD NEVER LOOK AT THE SUN THROUGH ANY OPTICAL INSTRUMENTS INCLUDING CAMERAS, BINOCULARS AND TELESCOPES WITHOUT USING A PROPERLY CERTIFIED SOLAR FILTER.

SUNGLASSES AND WELDING GLASS DO NOT OFFER ADEQUATE PROTETCION.

Sunspot Activity in Solar Cycle 25

With the skies being cloudy at night for sometime now and, with the recent development of some decent solar activity, my thoughts turned to the sun this afternoon. I didn't give myself much time as it was rapidly going down behind the neighbouring houses, but I did manage to get a couple of shots of the current active region known as AR 2781. 

Sunspots are temporary solar phenomena which are regions of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection. They are darker than the surrounding areas and occur in a region called the photosphere. Whereas the photosphere has a temperature of 5,800 degrees Kelvin, sunspots have temperatures of about 3,800 degrees K. They look dark only in comparison with the brighter and hotter regions of the photosphere around them and they usually appear in pairs of opposite magnetic polarity as well as moving across the sun's surface.

The designation AR stands for Active Region and the sunspots shown in these photos are part of the current Solar Cycle 25. NASA had this to say on their website:

Solar Cycle 25 has begun. 

The Solar Cycle 25 Prediction Panel, an international group of experts co-sponsored by NASA and NOAA, announced that solar minimum occurred in December 2019, marking the start of a new solar cycle. Because our Sun is so variable, it can take months after the fact to declare this event. Scientists use sunspots to track solar cycle progress; the dark blotches on the Sun are associated with solar activity, often as the origins for giant explosions – such as solar flares or coronal mass ejections – which can spew light, energy, and solar material into space.

Here's a cropped version of the above photo to show the sunspots in a little more detail:

To take these shots I had to dig out the solar filter I made for the Transit of Mercury back in November 2019 when I began to take my interest in astronomy a lot more seriously. 

It's really important to never look at the sun without proper protection - this doesn't mean just wearing sunglasses or even using a welding mask.  It's very dangerous to look directly at the sun through binoculars, telescopes and cameras and solar filters are made of a very complex layered material which offers great protection.  Even then, I only ever view the sun by looking at an image on the back of my camera, never through the eyepiece.

The Baader AstroSolar Safety Film I used to make the filter renders the image as more or less white, and indeed, this is the true colour of the light coming from the sun.  The orange hues we see by eye are mainly due to dust in the atmosphere, although some specialised filters do give the images a deeper orange colour.  Here's a simulation of that created by simply increasing my camera's white balance control.

Reprocessed Sunspot AR 2765

Sunspot AR 2765 - (13:24pm 5/6/20)

Reprocessed to enhance the faculae or bright areas near the actual sunspot.

Sunspots are temporary phenomena on the Sun's photosphere that appear as spots darker than the surrounding areas. They are regions of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection. Sunspots usually appear in pairs of opposite magnetic polarity. The Sun's magnetic field wells up to the photosphere which is the Sun's visible "surface". The powerful magnetic fields around sunspots produce active regions (AR) on the Sun, which often lead to solar flares and Coronal Mass Ejections (CMEs).

You Never Forget Your First Sunspot

Wow! I've just taken my first ever photo of a sunspot! Thanks to Anthony Wallace Cross from the Manchester Astronomical Society for the heads up.

AR 2765 (Lower left side)

A closer view:

WARNING: DO NOT LOOK DIRECTLY AT THE SUN THROUGH A CAMERA VIEWFINDER, BINOCULARS OR A TELESCOPE. ALWAYS USE A SPECIAL SOLAR FILTER AND CHECK THAT IT IS NOT DAMAGED.

Three Blokes in a Transit

Three Blokes in a Transit

The start of the 'Transit of Mercury' as seen from Ty Mawr Country Park, Rhuabon near Wrexham in North Wales on Monday 11 November 2019.

This story starts with a little fun astronomy group (Leigh Astro Society) that we set up back in October when three of us visited a dark sky location in the Forest of Bowland in search of Andromeda. The founding members of the L.A.S. were Paul Richardson, George Pike and myself.  Following this meeting I set up a Facebook group and the online membership has now grown to seventeen people, with around five people regularly posting photos or useful information for the group.

One of these posts concerned the approaching 'Transit of Mercury' which is a reasonably rare event and so some of us got interested in seeing and hopefully photographing it.

To do this we'd need solar filters for our 'scopes and camera lenses. Paul, who is the only true astronomer amongst us, had already made one previously for a telescope, which he then adapted to fit his camera.

I, on the other hand, am a compete novice to astrophotography and when I realised that Paul's filter wouldn't fit my camera so I couldn't borrow it, decided to make my own at the very last minute - two days before the transit in fact with one of those being a Sunday.

I'd left it too late for the required Baader AstroSolar Safety  Film to be delivered from an online source, and so after a frantic morning of phoning up every nearby camera and telescope shop without any luck, I decided I'd have to make the three-hour round trip to Rother Valley Optics near Sheffield to ensure that I got some in time.

Anyway, I did the trip, got the film and spent Sunday afternoon making two filters, one for my 500mm lens and the other for my 300mm lens just in case there were any issues.  I was reminded of the old Blue Peter programmes as I cut the required shapes out of card and then used double-sided tape and sticky-backed plastic to fix them together. It was tight making two filters out of a single piece of A4 film, but at nearly £20 a sheet I wasn't going to waste any of it!

Filters made, it was time to decide where we'd be going to get the best chance of seeing the sun.  The weather forecast wasn't good with a front bringing cloud and rain over the North West during the day.  Paul decided that North Wales would be the best place to try, with a couple of possible locations in mind, the first being Ty Mawr Country Park in Rhuabon near Wrexham. We turned up at George's house at 10am and by 10:15am we were on our way with George driving - well he had said he'd be willing to drive up to 50 miles to see the Transit and that was going to be more or less right.

One of the first photos I took of Mercury;

The small black speck on the left side of the sun isn't dust but the planet Mercury, which only passes in front of the sun every 15 years or so. Mercury is 57.91 million km away compared to the sun's 149.6 million km, so it's nearer to the Earth than the sun. It's also only 38% of the Earth's size.

It's so small that you'll need to view these fullscreen and it can't be seen with the naked eye. You must never look at the sun through bins or scopes unless you have a special solar filter which cuts out 99.99% of the light and radiation.

The actual colour of the sun is white but I increased the white balance in the first shot to make it the more familiar orange colour we see, which is caused by our atmosphere scattering the light.

It definitely seemed to become more orange as it descended below the hills.

And so to bed ...

The founding members of the Leigh Astro Society.