Solar observing: last year and now

My solar observing season tends to run from about February to the end of October. As I’ve noted before the Sun is too low to clear the roofs of the surrounding houses.

For the last few seasons I’ve been sketching the view of the solar disc through my Coronado PST (Personal Solar Telescope) and occasionally augmenting that with white light details of Active Regions (ARs).

I thought it might be interesting to compare the views from this time of year. I only started seriously recording at the end of the 2016 season, so the record isn’t a long one, but at least both the images below were made using the same equipment and are limited to Hα views.

At the first glance, and doubtless due to my artistic talents, you’ll find that the Sun appears to be about the same: not especially active. A closer look and a scan of the notes reveals that there’s quite a difference.

Hα sketch from 18 May 2017
Hα solar disc sketched on 18 May 2017 with a PST and Baader Zoom.

So to get the ball rolling I present my sketch and notes from mid-morning on the 18 May 2017.

This view is sporting three substantial ARs with a sunspot visible in the PST. For sunspots to appear in Hα normally means that they’re large and plain to see in white light, something I’ve noted. I also note being able to see even more sunspots that way.

There are also some good prominences and their cousins from the solar disc, the filaments. I’ve also added notes about the central AR12657 showing a tight knot in the fibrils that cover the surface of the Sun.

Hα sketch from 17 May 2018
Hα solar disc sketched on 17 May 2018 with a PST and Baader Zoom.

Moving on to my sketch from around midday on 17 May 2018 it’s a very different story.

I’ll admit that mid-morning is a much better time to observe the Sun than midday as the intense heat from the midday Sun stirs up turbulence in the atmosphere, but still, that is a quiet Sun!

Only AR12709 is visible with a pair of quiescent prominences – reasonably large though – and a few small filaments. There are no notes about the white light view because there was nothing much to see.

The next couple of years might provide more of this as we pass through a Solar Minimum. That’s not to say that we can’t get some excitement, it’s just not as likely nor frequent.

I’m hoping that the pessimists predicting a Solar Grand Minimum like the Maunder Minimum have got it wrong.

All that said, there’s the nice detailed AR12712 on the face of the Sun as I’m writing this (a little delayed by software issues) according to SolarMonitor.org. It’s got multiple spots and is now classed as type βγ which could produce some small scale fireworks.

Unfortunately for me it’s firmly on the wrong side of some persistent clouds and thunderstorms here in the UK. If you can see the Sun enjoy the view but always with the appropriate equipment.

Update!

Would you believe it the Sun came out this lunch time! I’ve had a good look in both Hα and white light and even got the time to make a sketch before the cloud returned. There’s a lot to see in AR12712, I wish the seeing has been a little steadier, but you can’t have everything.

Lunar highlights

Previously most of my lunar observing had been limited to the spectacular array of impact craters. Yet most of these contain details that passed me by until I was told to really look, and they only scratch the surface (so to speak) of what the Moon has to offer. Now I’ve surveyed 90% of the sights listed in the Lunar 100 list, what were the highlights?

Discovering Lunar domes and dark halo craters has lead me to consider lunar vulcanism more closely. The latter were completely new to me despite being easily visible under bright illumination. These are long extinct volcanoes or vents and probably a result of the impacts in the early life of the Moon.

Which leads me to the lunar rilles (rimae). I love trying to resolve those thins dark or bright lines, depending on the direction of the sunlight. They’re a real observing challenge though they range enormously in both complexity and size, some being much more easily spotted than others. Faults lines or collapsed lava tubes? They have different origins to investigate.

Likewise I’ve developed quite a soft spot for crater chains (catenae). The Davy Crater Chain is listed amongst the 100, but I’d never noticed it before attempting the list. I’ve discovered that there are several more of these structures which are the result of the Earth tearing a passing asteroid or comet apart. Remember Shoemaker/Levy? That’s what we’re talking about, albeit on a smaller scale.

This is the small scale detail so far and as much as I love this the Moon isn’t the Moon without those vast impact basins that for the Maria. They’re not hard to see, even with the naked eye they’re obvious, so what’s to learn?

Firstly I certainly know where to find more impact basins than before. I also enjoy trying to trace the multiple rings of mountains (I think of them as ripples) around many of them. The area around the Mare Vaporum is a favourite now because of its variety. Evidence of volcanism and the deep scouring by debris from the Imbrim impact, one of the biggest, is really obvious.

With a telescope and the right illumination the Imbrium lavas are covered in dorsa (wrinkle ridges). Initially I thought these were evidence of cooling lava flows. By working out the direction of slope as the illumination changed I hoped I could trace their origin. But I couldn’t because these are genuine ridges and not sloping ways from any centre. This is what happens when the marial lava cools and the impact basin sinks under its weight: the surface really wrinkles! The detail at modest magnification can be impressive, especially since it all disappears when the Sun is high.

This project started out as another observing list to tick off, but I’ve come to realise that misses the point of the Lunar 100. To get the most out of it you have to observe the features and then think about what they’re telling you about the geology and history of the Moon. More than any previous casual sessions, this project has lead me to identify features from continuing observation and research. I have a far better feel for the complexity of our nearest celestial neighbour.

Low Altitude Messiers

Back in February I noted that most of the remaining Messier Objects were too low to be seen from my back garden. Well I managed to fit an observing session in during one of our Society meetings to observe the Perseid meteors this August.

As it turned out it was cloudy most of the time, so very few meteors were seen, but during the early part of the night, before the Moon rose, I stuck my 10×50 binoculars on their monopod and pointed them low to the South in the direction of Sagittarius.

Messiers in Sagittarius and Scutum produced with Stellarium
View of the Messier Objects in Sagittarius and Scutum produced with Stellarium.

As you can clearly see there’s a lot to go at here! Unfortunately, even from this site trees obscured anything below the star Kaus Borealis marking the tip of the lid of the Sagittarius teapot.

I could get pretty close and that star was a nice bright marker, so I decided to begin with M22. It was immediately obvious to the East of Kaus Borealis and well clear of the trees. A large round fuzzy patch with no sign of resolving into stars. Just what you’d expect from a globular cluster in a pair of binoculars, or in fact in a small telescope. I panned to the West, but as expected M28 was not seen. It was obscured by the tips of those trees.

I was keen to bag the lowest of the objects on view, and typically enough the next target isn’t marked in the image above. I chose M8 (the Lagoon Nebula) which is that box below M20 and to the West of the last targets.

M8 was seen amidst a collection of brighter stars aligned east-west as a patch of nebulosity in direct vision. It’s nothing but a fuzzy patch which was about 7’x3’ in size when compared to the separation between the adjacent stars 7 Sgr and 9 Sgr. Truthfully, I suspect that I was primarily seeing the open clusters NGC6530/6523 forming within this emission nebula as they match the position of this patch.

M24 is an interesting target, and one made for binoculars. That’s because it’s the Sagittarius Star Cloud: a view through an interstellar dust cloud of the neighbouring galactic spiral arms. It’s a large and very obvious grouping of stars of various magnitudes, there’s nothing nebulous about this one! It spanned about ¼ of the binocular field of view, or about 75 arc-minutes, in its length and perhaps ⅓ of that in width (25 arc-minutes). It’s aligned roughly northeast-southwest.

I wondered whether I could find the open clusters in Scutum. Being the brightest M11 was the first on the list using the stars of Aquila as a signpost (Scutum isn’t very bright). To my surprise there it was as a modest sized, but bright condensation of stars. It was immediately obvious, but I couldn’t resolve an stars with the binoculars. I’ve managed to get a telescope on M11 from Home since and it’s a spectacular open cluster!

Down and to the West I sought and found M26 which was much smaller and fainter than M11. Definitely no stars to be seen in this one, and I haven’t viewed it telescopically yet.

I’d taken to starting my star hopping at M24 because it’s so obvious in binoculars, and fabulous to look at too. This time I noticed two more fuzzy patches to the northeast as the transparency improved.

The first spherical patch of nebulosity appeared above a convenient asterism allowing me to identify it as M18. Nebulous and unresolved I estimated it to be about 8 arc-minutes in diameter by comparison to the local stars separations.

Further to the North is a much more irregular patch in the right place to be M17 (the Swan Nebula). Again this was nebulous and unresolved. M16 (the Eagle Nebula) spotted as a nebulous patch around a coarse cluster of stars that formed a suitable pattern for a positive identification. No detail seen, but it’s clearly visible whilst not resolved. I estimated it to be 5 arc-minutes in size.

M16: the Eagle Nebula by ESO
Image Credit: ESO – Messier 16 (the Eagle Nebula)

These two objects are star forming in that dust cloud mentioned earlier. Without it the whole area would be as star filled as M24! On the other hand we wouldn’t have objects like M16 to look at, even if it didn’t look like that in my 10x50s.

Finally for the night I found M25 easily spotted to the East of M24 as a coarse and sparse open cluster that did resolve fairly easily. A range of magnitudes leads me to assess it as a Trumpler class II2m open cluster.

And that was the end of a very good night’s work with the binoculars. Nothing I viewed that night was particularly taxing, many other Messier objects are much trickier. It’s a lovely part of the night sky and there are more to capture here, but I think that’ll have to wait for next year as time and the weather have not been kind.

The Return of Solar Observing

As the days of British Summer Time get longer a compensation for me is that the Sun is rising high enough to be visible again from my northwest facing garden.

I love my solar observing in both the Hydrogen Alpha (Hα) wavelength of the Balmer series, using a Coronado Personal Solar Telescope (PST), and with a normal telescope in white light, but with a Herschel Wedge removing around 99% of the available light for safe observing.

Considering that we’re near solar minimum there’s been a surprising amount of activity to be seen around the end of March and the beginning of April. The most dramatic events have been in Hα, but even white light views have been impressive. The cause of the excitement has been a pair of large Active Regions (ARs).

The first of these (AR12644) produced some large eruptive prominences as it exited the face of the solar disc on 3 April. I was lucky enough to be observing then with the PST with a Baader Zoom eyepiece, and the events were fabulous.

I don’t image, and was too busy observing to sketch, but fortunately NASA does image almost continuously with the Solar Dynamics Observatory (SDO) from orbit. This is what they came up with, and despite their use of the ultraviolet part of the spectrum it’s not too far from the PST view in the red of Hα (656.3nm).

SDO image of AR12644 at 30.4nm taken on 3 April 2017
An image of AR12644 on 3 April 2017 at 30.4nm wavelength by the Solar Dynamics Observatory (SDO). Credit: Solar Dynamics Observatory, NASA.

It is just a little more detailed and has a larger image scale. They also have some movies of this solar eruption, and trust me, you could see that big prominence changing before your eyes!

I checked out the white light view too, but there was no indication of the violent events to be seen. The clusters of sunspots and surrounding faculae were plain to see in all their intricate detail despite sitting right on the limb in the image below. It was taken by the SDO HMI instrument, but is very similar to my white light view.

SDO HMI Intensitygram of AR12644 and AR12645 taken on 3 April 2017
HMI Intensitygram of AR12644 and AR12645 3 April 2017. Credit: Solar Dynamics Observatory, NASA.

In its wake followed the equally large AR12645 in the lower left of the image below. If anything it was more impressively detailed in the wedge, and I found it to be naked eye visible through some Baader solar film (another method for safely viewing the Sun). It didn’t produce any Hα fireworks, but the sharp filaments and swirling patterns in the spicule and fibril background of the solar chromosphere were beautiful to observe.

These ARs were great to view throughout their transit across the face of the Sun, but will they survive to reappear for another transit?

A Feast of Astronomical Observing

And now I’ve forgotten to post through March… which is a shame because it was a huge improvement over February. Not only a big uptick in the quantity of observing opportunities, but lots of variety in my observing diet too.

Both this month and the last have started with some Lunar observing. I’m starting to take this increasingly seriously just as the Moon is due to sink lower in my sky until it disappears behind the house until Autumn… still you have to start sometime, and I’ve decided now with the Charles Wood’s Lunar 100.

Which is why I’m very happy to welcome the return of solar observing. As the Moon sinks, the Sun is getting higher in our northern hemisphere skies, so it’s around now that I start to swap lunar for solar observing. Despite being around solar minimum, with relatively few sunspots to be seen, I’ve been rewarded with some Hα fireworks and spectacular white light sunspots in the last few weeks. Few in number perhaps, but the quality was undiminished.

Planetary observing wasn’t left out as I followed the sliver of Venus up to the last possible moment. For me that was the point it fell behind the houses and trees to the west at sunset on 15 March 2017, but it was a very thin crescent by then: I estimated 5% and Stellarium claims 4.4% illumination. I’ve caught a glimpse of Mercury at sunset too.

There were several Jovian sessions, even though it’s a bit too low to see well from my back garden. I can observe Jupiter low to the SE over the top of my garage for about 30 minutes before it goes behind the house. No moon transits yet, but a look at a slightly washed out Great Red Spot (GRS) was possible in my 60mm refractor. Why the small scope? To have any view I have to pick my position carefully, and you try manhandling a large telescope into the garden undergrowth.

I’ve tried to spot the comets 45P/Honda and C/2015 V2 (Johnson) with my binoculars, but with no success. At first they were too faint or low, then the Moon arrived and I haven’t bothered again. Once the Moon disappears I’ll certainly try again for the latter of the two at least.

March witnessed the arrival of British Summer Time (BST) which heralds the rapid shortening of night in these parts. Naturally in astronomical circles this is never well received, and Deep-Sky observing isn’t going to be easy! By the end of May there’s no astronomical darkness for a couple of months, but in the meantime there can be some lovely transparent skies for the patient.

After a rather wet period in the middle of March, during which the Moon got out of the way, clear skies returned just before BST inflicted itself upon us. I’ve started working on the Herschel 400 list again. This spread of several nights gave me the chance to start on the faint and fuzzy galaxies of Spring, as well as polishing off some surprisingly faint open clusters from late Winter.

Finally, I’ve collected a few more variable star observations thus clearing the backlog a bit and responding to an AAVSO alert on AG Dra (one I regularly follow). The conditions haven’t been great for it: patchy cloud doesn’t kill a lunar session, but it makes reliable binocular variable estimates pretty tricky. Still it’s nice to be logging some data again.

So a March was a much better month and April has started in stunning style with observing sessions on each of the first seven days!

Binocular Messiers

You may remember way back in 2014 I wrote about Charles Messier and his list of comet-like objects. I also mentioned that I’d started tracking them down with binoculars, and that was a while ago, so what’s happened since?

I’m still working to my usual leisurely pace, but I’ve collected good observations of 60 of them now. This year would be a great time to finish this project since it’s the 200th anniversary of Charles’ death. The BAA are encouraging observers to complete a Messier Marathon, or at least view all the objects this year. Perhaps I will.

I’m basing my work on the Astronomical League’s Binocular Messiers Program that rate 102 of the 110 to be observable with binoculars. I’ve set the additional challenge to observe as many as possible from my north-west facing back garden. This is one reason why it’s taking so long to complete the project: some objects have a very short window of opportunity. That said, I seem to have managed a couple they don’t think I should be able to see, but I stand by my observations ;-), and having observed 58 from their list have 44 left to go.

Unfortunately most of those are pretty low in the sky from the UK. For example, I snagged M41 in Canis Major a few nights ago as it briefly appeared from behind the row of houses before falling into the trees, and all whilst standing on top of a wall peering through the undergrowth. On the other hand I couldn’t have done that with a telescope! I’m very glad that M41 is big and bright or the Industrial Estate light pollution would have rendered it invisible.

Image Credit: M41 by Digitized Sky Survey (DSS)
Image Credit: M41 taken from the Digitized Sky Survey (DSS) using Aladin Sky Atlas.

The upcoming galaxies of Virgo and Coma Berenices may cause some problems. I’ve observed all the brighter ones and have the trickiest to collect on a night of really good transparency. I’ll have another go at M108 and M109 in Ursa Major on that night too.

Then I’m down to the horizon huggers of Scorpio and Sagittarius below 25° altitude. I can’t think of anywhere around my house that they’re possible. Not the street outside, our front bedroom window, they’d probably be difficult from the roof. So I’ll have to start being mobile to mop the rest up, and perhaps that’s the time for a marathon?

My Variables Stars

As a follow up to the post on starting out observing variable stars I thought I’d talk about my journey.

I started variable star observing about four years ago with the naked eye and the 10-Star tutorial. I soon moved on to binocular variables, to which I’ve added a smattering of telescopic Mira variables now.

As you can see below, fuelled with enthusiasm soon clocked up 200, receiving a certificate from the AAVSO for my first 100, which was unexpected. Then the observation rate started to drop for various reasons including the appalling weather, British summer time (these two are often linked), and the pursuit of other astronomical interests. It stalled drastically after the first 600.

120 day binned cumulative variable star observations
My variable star observation count up to 19 January 2017.

Well at the end of 2016, I decided it was time to pick up the slack and at least push through the 1000 observations barrier, which I did on 5 October 2016. At the time I generated the chart for this post I was handful short of the 1100 observation mark, but another clear night has put me well over the top.

Choosing my variable stars

I’ve got a telescopic aperture limit of 6 inches and a relatively light polluted site so those exciting, but faint, cataclysmic variables are off the menu for me. Eclipsing binaries are fine, but the most valuable observations of these are CCD photometric these days: visual observers need not apply. Most of my efforts are aimed at Long Period Variables (LPVs) with a few other types thrown in for variety, and delta Cephei for nostalgia.

I choose variables to suit the magnitude range of my equipment and by constellation. The latter allows me to concentrate my effort in a smaller area of the sky: it’s an efficiency thing. I also have favourite constellations: it’s a personal thing, and possibly pragmatic too 😉

My back garden has a terrible horizon for an amateur astronomer. Houses block most of the lower 30 degrees of the sky to the south and east, there’s heavy light pollution to the west now from an industrial estate, but I’ve a much better northern horizon.

For that reason I tend to favour circumpolar constellations that are accessible all year round, providing an unbroken record of observations. I’m concentrating on Cassiopeia, Cepheus, Draco, Ursa Minor and Ursa Major.

There are currently 49 variable stars on my observing list of which I have to admit only 30 get regular attention at the moment, and all of those are in the constellations mentioned above.

Making observations

I use a combination of instruments depending on the brightness of the star and the sky conditions.

I can monitor variables with magnitude brighter than 5 with my naked eye (as long as I’ve got my glasses on!). A pair of 2.1x binoculars extends this to 7, but from around there down to magnitude 9 can be handled by a 10×50 binocular on a good night, and 15×70 binoculars for the fainter end on a night of poor transparency.

These can be pushed to magnitude 10, but around that I fall back on my first telescope: a Skywatcher 130P (130mm F5) newtonian. With the right eyepieces it provides good 1 and 2 degree field of view, which is plenty of room for the variable and comparison stars near the centre.

My final limit is about magnitude 12–13 depending mostly on altitude and transparency.

A good example is the recent CTA 102 quasar which reached around magnitude 11.5 and should have been possible. But by the time I had a clear sky – bad weather – CTA 102 was low in the western sky glow and had faded to magnitude 12.7. With the Moon right on its doorstep it proved just too faint for any of my telescopes. I suspected as much, but its not every day you get the chance to see something eight billion light years away with your own eyes, so I had to have a go! I found the field stars, but no quasar. I could have filed a “fainter than” observation, but it didn’t seem worth it when I was limited to 11.4.

I try to observe these rare opportunities – the Nova V339 Delphini and SN2014J in M82 spring to mind – as they’re not often within my range of magnitudes or a part of the sky I can see.

Making regular observations of selected stars really has its benefits though, quite apart from the fun of following their progress. Practice makes perfect and with the comparison stars fresh in my mind I can manage one observation every three minutes, which is quick by my meagre standards, and maintain this rate for a couple of hours.

I just noticed on the AAVSO website that I might get another award for the first 1000 observations. I also noticed that the next milestone is 5000!

Experiences of Remote Imaging

Way back in at the beginning of 2014 I wrote about remote imaging. I know, not very analogue, but my reasoning is that using robotic telescopes wouldn’t cost me valuable observing time under clear night skies.

In this post I want to talk about how this works in practice and whether astro-imaging and astro-photography are really the same thing. I learned a bit about which one interests me the most… Continue reading “Experiences of Remote Imaging”

Starting to Observe Variable Stars

If you’ve read the “about me” page you’ll know that I’m a fan of variable stars. Most of my astronomy colleagues think it’s a bit weird, but I love to test the ability of my eyes to judge brightness and follow the changes in the 30 stars on my regular programme. I now use my naked eye, binoculars and a telescope to observe variables, but I didn’t start that way… Continue reading “Starting to Observe Variable Stars”

The Veil Nebula in a small scope

I’ve become a little obsessed with observing this particular supernova remnant. I think it’s because it can show lots of nebulous goodness under less than perfect skies and with less aperture than some: it’s a realistic target.

That said, it’s not straightforward with a light polluted sky, but mid-summer is the best time to try with Cygnus right overhead, and that’s what I do every year.

I’ll admit to being a little late with this post, but I hope you’ll bear with me since this tale was certainly an observing highlight of 2016. Just imagine that it’s August and time to start my annual Veil Nebula hunt… Continue reading “The Veil Nebula in a small scope”