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Symbolic Forest

A homage to loading screens.

Blog : Post Category : Geekery : Page 7

End things as you mean to go on

Looking up at the sky again

Happy New Year!

Last night was the first clear night for a few weeks; and the only clear night at any point in the forthcoming weather forecast. Naturally, as soon as I mentioned the clear skies to The Children, they immediately jumped up and down and shouted “LET’S GET THE TELESCOPE OUT!”

The decking was already slippery with frost, and there was a lot of light and noise from the surrounding houses, but we started out by pointing the telescope to Enif (ε Pegasi), a red supergiant with a very distinctive orange colour. From there we navigated to the nearby globular cluster Messier 15, which I could see in the telescope as a somewhat hazy blob, but which The Children weren’t sure they could actually see.

After they were in bed, I went outside again and looked up at the sky, but it was already filling up with haze and smoke from the fireworks sporadically going off all around the neighbourhood. I tried to find Messier 36, an open cluster in Auriga apparently also called the Pinwheel Cluster, but could not actually make out any of the stars in it. I looked at the Pleiades to calibrate myself, and realised there seemed to be far fewer of its stars visible than normal. As Orion was rising higher in the sky I pointed the telescope at the Orion Nebula, just about visible as a couple of fuzzy points; and the nearby Coal Car Cluster (NGC 1981). The latter’s stars are around magnitude 6.4 to 7.4, which normally would be clearly visible in the telescope even in our inner-city skies, but with last night’s firework haze I could just about make them out.

Ah well, there will be clear nights later in the winter I’m sure. I got up again about 3am to get myself a drink, and the garden was covered in a thick fog of smoke still from all the fireworks of midnight. Fireworks and astronomy do not mix. Hopefully later in the year, too, we’ll be able to take the telescope to somewhere with properly dark skies one night.

Cloudy skies

And not much we can do about it

Sadly, I didn’t get to see the Great Conjunction of Jupiter and Saturn, at least not at the closest approach that would have been visible. We had heavy rain here this afternoon; and after sunset the sky was a uniform, undifferentiated cloudy mass with not even the moon visible.

Oh well: we had clear skies last night, at least, and I did see them both, maybe only about 10 minutes or so apart in the sky, just over the horizon after sunset. I tried to take a photo on my phone, but although Jupiter was clearly visible on it, Saturn was only really spottable if you already knew it was there. Maybe it’ll be clear skies tomorrow, when they are parting again.

The solstice has passed too, of course. Politically this country might seem be descending into some sort of nightmarish *fimbulvetr* right now, but at least the heavens don’t know that.

The shape of the sky

Or, confusing perceptions

This is an astronomy post, but it’s also not really an astronomy post; it’s more a post about me and the way I think.

When I was small, I was terrified by the size of the universe. I can remember, about seven or eight or so, really struggling with the concept that the universe might be infinite and might not be, and I can still remember the mental picture I tried to come up with of a universe where the stars just, at some point, stopped; and beyond there was just blackness.

It probably doesn’t work like that, but still in my head somewhere is the concept that it might do. Moreover, I have trouble with another, broader concept, which is that—assuming you can travel between both hemispheres—we can “see” all of the observable universe.

“See” is in quotes there because, well, you can’t see everything for practical reasons. Most things are too faint, firstly. At any given time half the sky is too close to the Sun, too: you can’t see Mercury right now for example. But in theory, barring things being too faint, barring you having to wait for the Earth to move a bit or having to travel from one side of the Equator to the other, the whole universe is up above some point on the planet’s surface at any given time.

This probably seems tediously self-evident if you think of the planet as a ball spinning through space. For some reason, though, the whole concept still catches me by surprise occasionally. I still think that things must be able to, I don’t know, hide around a corner or something like that. I think I must have picked up the idea from a book I had as a child about Halley’s Comet, which included diagrams of where you would be able to see the comet in the sky in 1986, and talked about how comets appeared and disappeared in the sky. That’s the general tone when talking about comets and asteroids and so on: they appear in the sky and they disappear again. So it took me a long time to realise that all of the comets and all of the asteroids are up there, in front of us, all along; we just can’t see them right now. Halley’s comet doesn’t just pop out from behind a tree every seventy-five years: it’s up there in the sky the whole time, just not visible.

Halley’s comet is maybe a bad example for this. Because it’s so famous, and because of the light-gathering power of modern telescopes, we can now track it through its entire orbit. According to Stellarium it’s currently at coordinates 8h26m/+1°46’, but as it’s only a few years from perigee it’s an incredibly-faint magnitude 25.5 so will appear as a just a fuzzy handful of pixels on any photo. Nevertheless, if you go outside tonight and look up at the constellation Hydra close to its tripoint with Monoceros and Canis Minor, up there it is. As are all the others. Everything in the sky that you’re likely to see in your lifetime is already up there in the sky, just invisible and unrecognised. And despite the fact that I know this, that I know on a rough, superficial level how the mechanics of cosmology work, it still feels a little strange to me. It still feels in my mind as if there should be some patch of the sky that we can’t see, that is hiding around some sort of galactic corner.

Whenever I see diagrams of the whole sky that say “this is the whole universe”—cosmic background radiation maps, for example—I’m slightly disturbed that in some sense the whole universe fits into one small image. “Surely it must be bigger?” my mind ends up thinking. The edges trick me: that’s not the edge of the universe, it’s just an artifact of plotting a spherical sky onto a flat piece of paper, just like any sort of atlas. The mental disconnect, though, leaves me feeling deeply uncomfortable.

Really, what I feel I should inspire me here is to take away that the night sky is far more mysterious and secretive than we know. It’s not just laid out flat in front of us as it appears to be: it’s full of unknown things and unanswered questions, even though all of them are genuinely sitting right there up above us somewhere. I don’t know if I’ll ever manage to change the way my head thinks about the night sky, but if I can, there is a whole universe of wonder concealed but fully within sight.

The stag cry and the slaughter

Or, the turning of the year

A few weeks ago, I read on Twitter—sadly I seem to have lost the reference—that the Welsh Hydref, used for either the month of October or autumn as a whole, originally had the literal meaning of “stag-cry”. From that, it turned into “stag-rutting season” and hence autumn. Geiriadur Prifysgol Cymru lists “stag-rutting”, but not “stag-cry”.

Moreover, November, mis Tachwedd, literally means “the month of slaughter”. Together, I think they make a beautifully evocative phrase. The stag-cry and the slaughter. Winter is setting in.

I spent a while sitting outside on clear nights over the past week, hoping to see the Geminid meteor shower. Nothing much, sadly, came of it. On Saturday, though, I did see a handful of meteors in the night sky. I’ve always looked for summer meteors before, flashing across the sky in a razor-thin line; but these were relatively slow-moving, fat things. I say “slow-moving”: they still crossed my field of view in little more than an instant. Their light was a much broader line, though, tapering at start and finish. If nothing else, it gave me good inspiration for the story I posted yesterday. Hopefully I’ll have better luck when the Geminids come around again next year. This year, though, is now nearly at an end. The stag-cry and the slaughter, and winter is upon us again.

Astronomy news of the week

Or, how to spot a shooting star or two

This is not going to turn into an astronomy blog, I promise, and I know I already mentioned some exciting upcoming astronomy news just over a week ago. There is something else interesting and astronomical happening in December, though.

In the meantime, the clouds did briefly break on Saturday evening to give us our first chance of using The Child Who Likes Space’s telescope without the moon shining bright in the south. We had a look at Mars, and then I successfully found Uranus, navigating downwards from Sheratan, the nearest naked-eye star I could easily pick out; it’s currently near to the boundary between Aries and Cetus. Looking just like another blue star, I would have had no idea, without guiding myself with a map on the computer, that we were looking at a planet instead.

And then, naturally, I started sending messages to people saying “Guess what? I’ve been spying on Uranus”, because I still have the sophisticated sense of humour of a ten-year-old.

The exciting event that’s coming up in a week or so’s time is: the Geminid meteor shower. I say “coming up”: it’s expected to be at its strongest at around 2 in the morning next Monday (the 14th), but if it is a strong shower this year, there should be activity visible for a few hours either side of that time, and even for a few days. Incidentally, because of the geometry of how meteor showers work—they happen when the Earth passes through the trail of dust left behind a comet or asteroid—the peak time is the same wherever you are, with the location of the peak moving around the planet as it spins. The Geminids were first noticed in the 1860s, but their “parent”, the asteroid 3200 Phaethon, was not discovered until 120 years or so later.

I’m not sure I’m going to risk keeping The Child Who Likes Space up until midnight to watch for meteors, much as I’m sure he would like to. If the skies are clear late one night this week, though, I might try wrapping up warmly and setting up my deckchair in the garden. There’s no point trying to use a telescope or binoculars to spot meteors; all you need is a comfy chair you can lie back in and look up at the sky. Give your eyes half an hour to adapt to the dark, then look up, look around, and wait for them to streak across the sky.

More astronomy news

A significant event is coming up

One last astronomy post for a while, and then I’ll talk about something different, I promise: in a few weeks time, on December 21st Saturn and Jupiter will be at their closest conjunction for several hundred years.

The Plain People Of The Internet: Conwhatnow?

They’ll come close together in the sky. The closest they’ll be for a few hundred years, in fact. They’re already fairly close in the sky right now, but on December 21st they’ll be so close that to some people they’ll look like a single spot of light, although people with 20/20 vision should still be able to see they are two separate dots.

Unfortunately … I’m not sure I’ll be able to see it. They’re both on the far side of the sun from us right now, and we’re basically watching Jupiter passing in front of Saturn from our perspective on the other side of the solar system. Because of this, they’re also fairly close to the sun in the sky, which means you don’t get a very long window of opportunity to see them. They will set together in the south-west sky only about 90 minutes after the sun does, so you have a brief window of time to see them together at dusk. If you’re on a south coast then things are grand; if you’re in a town, they may well be already below your neighbour’s roofline before the sky gets dark enough to see them. Personally, our only chance will be from an upstairs window. Fingers crossed, though, the sky will be clear enough to see something of them both together.

One of our galaxies is missing!

Or, more astronomy for beginners

Yesterday afternoon, sitting at my desk as dusk was falling, the skies were clear and I could clearly see the moon and Mars rising in the sky. As soon as I logged off from work, I scampered downstairs and went outside, and saw Jupiter and Saturn just visible above the rooftops at the back of the house. “Let’s get the telescope!” I said to The Child Who Likes Animals Space. “Before they set!”

“Before what set?” said The Child, but I was already rushing off to get his telescope and set it up in the back garden.

By the time I’d hoicked it out of its box, Jupiter had already gone down below the roofline, but Saturn was still there. Sadly, I could only see it when I was stood up. The telescope, sitting on a camping table, was too low down to spot it. I briefly considered setting the smaller camping table on top of the larger camping table and making some sort of rickety makeshift telescope-tower, but it would probably have ended in some sort of injury to one or both of us. So, like we’d done before, we looked at the moon, we looked at Mars, and we looked at random bright stars. “Point it at that blue thing!” he shouted. “That’s a very hot star!” This time, at least, he was a lot calmer and could stand still looking through the eyepiece without having to break off every couple of seconds to run back and forth with excitement. I experimented with holding my phone camera in front of the eyepiece. Worst. Astrophotography. Ever.

Worst. Astrophotography. Ever.

After The Children decided they’d rather go inside and watch TV I left the telescope set up; and after they’d gone to bed, the skies were still clear. Time for some telescope practice for me, I decided. Using an app on my phone to show me roughly where things were, I tried focusing on key visible stars then swinging the telescope sideways to find a nearby Messier object. The results? Not very successful, other than a possible sighting of M29, the Cooling Tower Cluster.

Getting a rough fix and vaguely hoping to spot the thing clearly wasn’t working. So, I fetched my laptop, and fired up Stellarium in Night Mode. I picked a target—the Triangulum Galaxy—and went looking for it.

Although the skies were clear, the seeing wasn’t great. Even a newbie like me could tell that the seeing wasn’t good. Vega normally stands out to me like a sore thumb, but last night it didn’t really appear any brighter or more significant than the stars of the Northern Cross to its south, which normally are noticably fainter. Nevertheless, I could see Hamal and Sheratan, the brightest stars in Aries, and could spot the telescope nicely onto Hamal and swing it between the two. Zooming in on Hamal in Stellarium, and flicking my head back and forth from the telescope eyepiece to the dim red screen of the computer, I could slowly navigate my way upwards from star to star until I reached Mothallah, which I hadn’t managed to see with the naked eye.

Road map of the stars

From there, I could similarly hop south towards the spot where the Triangulum Galaxy should be, navigating from star to star and matching the scene in the sky to the screen of the computer. But when I reached it: nothing. Just a blank patch of sky. I found Mothallah again, then worked my way across by a different route. Still nothing. The Triangulum Galaxy has been stolen!

Let’s try the Andromeda Galaxy instead, I thought, given that it’s one of the brightest galaxies in the sky. I found Mirach by eye, spotted the telescope on to it, and walked over to where the galaxy should be. Another blank patch of sky, with a faint hazy blob in the middle of it. Hurrah! A faint hazy blob!

I’m almost glad I hadn’t found it the other day when The Child Who Likes Animals had asked me to find it, because I suspect if I had he’d have been awfully disappointed. I was a bit puzzled, though, because in theory the Andromeda Galaxy is of naked-eye magnitude. I should have seen much more than a fuzzy blob, surely?

A quick note about how astronomical “apparent magnitude”, or brightness to you and me, works. It’s a relative scale based loosely on the subjective scales used by ancient astronomers, and as it’s relative it’s written down as a number without units. The higher the number, the fainter the thing is; and a difference of five in the apparent magnitude number means “a hundred times brighter”. If you have a calculator to hand you can work out that a drop in magnitude of 1 therefore means “2.5119 times brighter”.* The star Vega, mentioned earlier, has magnitude 0, so a few things in the sky have negative magnitudes: Sirius is -1.47, Jupiter varies from -1.66 to -2.94, and Venus from -2.98 to -4.92, almost 100 times as bright as Vega.

On a good night, with a clear dark sky, the human eye should in theory be able to see things as faint as magnitude 6 or so. Last night was clearly nowhere near that: I could see Sheratan at 2.655 and Albeiro (in the Northern Cross of Cygnus) at 3, but couldn’t see Mothallah at 3.42. Through the telescope, though, I was happily stepping my way across the sky using stars of 8 to 8.4, roughly speaking, stars around 140 times less bright than the faintest I could see without it.

The Triangulum galaxy, though, is officially** of magnitude 5.72. Andromeda is considerably brighter still, around the same magnitude as Mothallah. So what was going on?

A galaxy isn’t a point of light, like nearly all stars are. Nearly every star in the sky, other than a handful of stars like Betelgeuse when seen through very high magnifications, appears to be just a single point of light to the viewer here on Earth. A galaxy, by comparison, covers a broad chunk of the sky. That small fuzzy blob I could make out in Andromeda was really just the very brightest core of the galaxy; and the rest of that 3.4 magnitude of light is spread out over an area wide enough to fill my entire eyepiece. Through the telescope, it just becomes a vaguely paler area of sky.

Hopefully at some point we will get the telescope out on a night with rather better viewing conditions, and be able to see all of these things properly. Until then, it seems strangely unintuitive to be able to see hundreds of dimmer stars but not a theoretically many-times-brighter galaxy. That, though, is just how the physics works.

* Apparently, the formal definition “five means a factor of 100” was set down by a Victorian astronomer with what I think is a great name, N R Pogson. The relationship 1:2.5119 is therefore known as Pogson’s Ratio.

** I say “officially”. I mean “according to what I’ve just read on Wikipedia”, of course.

Astronomy

The art of not seeing very much (as yet)

The other day I mentioned The Children have just turned seven. As The Child Who Likes Animals has spent quite a lot of time in recent months liking space instead, watching Brian Cox’s The Planets innumerable times, memorising lists of dwarf planets, Kuiper Belt objects, centaurs and so on, and learning the difference between a red dwarf, a white dwarf and a brown dwarf. We decided, therefore, that it might be a nice idea for The Mother to get him a telescope, as a suitably grandmothery sort of present. Not trusting The Mother to judge what might be suitable, I reached out to a few astronomers I know for recommendations, and found something that both fell into The Mother’s budget and had a reasonable chance of imaging the rings of Saturn. The number of times I’ve looked down a telescope myself before can be counted on the fingers of one hand; but if I was age seven, was given a telescope, and found that it couldn’t show the rings of Saturn I’d be terribly disappointed.

Of course, I messed up to a certain extent. I’m sure I achieved my objectives, but there’s no way really that The Child Who Likes Animals would be able to actually point the telescope at something himself. So, this is going to be the sort of present that one of his mums sets up in the garden on dark nights; find out what he wants to point it at; try to point it; and then he looks down the eyepiece. Naturally, it becomes a family event, with The Child Who Likes Fairies also wanting to get involved.

As I said, I’ve hardly ever been near a telescope before, despite having books and books on astronomy when I was that age myself. So, on the few nights we’ve had so far when the cloud has at least been broken rather than blanketing, it has gone something like this: I set up the telescope outside. A child asks to point it at something, in a brief pause for breath whilst running around with crazed excitement. If it is an easy thing—the moon, say—I contort myself to the right angle to try to see through the finder, point the telescope and roughly nudge it about until we can see what we’re looking for, all the time with said thing bouncing up and down in the eyepiece as children bounce up and down on the decking. A child then steps up, instinctively grabs the telescope and knocks it out of alignment, and we go back to square one.

Eventually everyone has seen what we’re looking at, and one of them will name something else. I try to work out how to find it, with my laptop and a copy of Stellarium. I fail to find it, and end up sawing the telescope back and forth across the sky desperately trying to find the thing they have asked for. I try again with the finder, drape myself over the telescope and twist it around until the red finder dot is in just the right place; then look through the eyepiece and see nothing but haze. I look up at the sky again, and my target patch of sky, clear a few moments before, is suddenly covered in thick cloud. This cycle repeats a few times, until we either look at the moon again instead, or The Children get bored and go back into the house.

So far, we’ve successfully looked at the moon, Mars, and some random patches of sky that have lots of stars in but nothing I can actually put a name to. Oh well. I’m sure at some point we will get the hang of it, even if I end up becoming the main telescope user myself. It certainly has shown me just how non-empty an empty-looking patch of sky actually is, even living in a hazy, foggy, light-polluted city like this one. I’ll let you know if I manage to find anything less easy to spot. Or, indeed, if we do ever see the rings of Saturn.

The mighty chopper

Or, an eye for detail

Regular readers will know I’m the sort of person who always has an eye for odd little details, odd little quirks of history or mechanical gubbins. You’ll probably be unsurprised to know that this has never really changed much.

Last week I posted photos of my first ever trip to the Ffestiniog Railway, from back when I was still in primary school. I can still remember being intrigued by the “chopper” couplings the Ffestiniog has used as standard since the 1950s (and to some degree since the 1870s—naturally the full details are online). I can’t say it was the first time I had seen them, but it was the first time I had been close enough to notice they were a novelty to me, enough for me to want to take photographs of how they work. So, naturally, I did.

Coupling on Car 100

This is my grainy 110-film photo of the coupling on FfR Car 100. On the far left is its electrical connector, with a hood to shelter it. In the middle is the coupling: a central buffer with a hinged hook fitting into a slot, and a weight (the “bob”) hanging below. Bear in mind that when I took this picture I didn’t know any of this; I was just intrigued by this peculiar metal prong. I’ve learned the technical details since.

Car and loco coupled together

After the loco (Mountaineer) coupled up to the train, this is what it looked like. The hook on each coupling is swung down into the opposite slot, but initially it doesn’t drop all the way; it’s blocked by a camshaft attached to the bob. The bob is swung to one side until the hook drops into its running position, and then swung back; the bob’s camshaft locks the hook into place and prevents it lifting. After that, you can attach the brake hoses.

Nowadays, of course, there are probably a thousand videos of how this works online, that you can go and watch whenever you like. I’m quietly pleased with myself, though, that back in the day when you couldn’t do that, this is the sort of thing I felt worth recording on film.

Technical advice post of the week

Or, what to do with a particular compilation problem

This week, Microsoft released .NET 5, and it reminded me I’ve been meaning to post a piece of technical advice that has bitten me a few times but which doesn’t seem to be very well-documented or well-described online. It’s a piece of technical advice, though, that will slowly be fading away in relevance because it’s advice on .NET Framework; so I thought I should put it up here whilst it is still helpful to people.

(Note for non-technical readers, who are used to photos of trains and cemeteries and probably won’t find this post very interesting: .NET 5 is the latest version of .NET Core, which is the replacement for .NET Framework, hence Microsoft have dropped “Core” from the name to try to make that clearer. .NET 5 is the successor to .NET Core 3, because there were many very popular versions of .NET Framework 4.x which were and are heavily used for a long time, so Microsoft thought reusing the number 4 would be just Too Confusing. Are you less confused now?)

This problem, too, is pretty much specific to people working in teams. It only happens (well, I’ve only seen it happen) if all of the following apply:

  • you’re working in parallel in a team, on a complex system, probably that has solutions containing a relatively large number of projects
  • you’re using the MSBuild tool as part of your continuous integration pipeline, deployment process, or similar
  • you’re using Git as your version control system

The symptoms of the problem are:

  • You can open the solution in Visual Studio and build it with no problems
  • When MSBuild tries to build the solution, it immediately errors, claiming that the solution file has a syntax error on line 2.

Spoiler: there is no syntax error on line 2.

Another note for non-technical readers who are still here: what you might think of loosely as a programming project, in any kind of .NET flavour, has a primary file called a “solution” (its name ends in .sln). The solution contains one or more “projects”; each project contains code. Visual Studio can open your solution file and your project files and turn the projects into some sort of output product, such as a program, a website, a code library or whatever. However, you don’t have to use Visual Studio to do this. .NET Framework has a program called MSBuild that does the same thing. If you have automated your build process (which if you’re working in a team you probably should) and you’re using .NET Framework, your build process will probably use MSBuild to do its work. What happens here is one of a range of problems called “well it worked on my machine”. A developer has code that seems to be in a happy, working state, they upload their code to the team’s server, the automated build process runs, and the automated build process falls over and says it doesn’t work.

The cause of the problem is: two people on the team have added different projects to the solution, in parallel. Now, Git is often quite good, when two people change code at the same time, at either working out how to merge the changes together, or at least, asking you to sort the situation out manually. This, though, is a situation where Git does the wrong thing and breaks your solution file—but it breaks it in a way that only MSBuild notices, and that Visual Studio happily ignores.

The reason this happens is down to the syntax of solution files. The part which lists the projects they contain looks a bit like this:

Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Important.Project.Library", "Important.Project.Library\Important.Project.Library.csproj", "{E6FF8E04-A41D-446B-9F8A-CCFAF4B08AD2}"
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Important.Project", "Important.Project\Important.Project.csproj", "{9A7E2940-50B8-4F3A-A535-AB6220E6CE3A}"
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Important.Project.Tests", "Important.Project.Tests\Important.Project.Tests.csproj", "{68035DDB-1C24-407C-B6B3-32CEC1D964E5}"
EndProject

Don’t worry too much about what each line says: the important thing to spot is that each project has a pair of lines: a Project(...) = line that contains the important information, and an EndProject line that, er, doesn’t. The projects are in a fairly arbitrary order, too; on your screen in Visual Studio they get sorted alphabetically, but that isn’t reflected in the file, where they are in the order they were added in.

The real cause of the problem is that Git doesn’t know that every Project... has to be followed by an EndProject. So, imagine two people have added new, different projects to the solution file. Git sees this and thinks: Alice has added Project... to line 42, and Bob has added a different Project... to line 42. So I’ll make those into lines 42 and 43. Alice added EndProject to line 43, and so did Bob, so I’ll just pop that in as line 44. So you get this:

Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Alices.Library", "Alices.Library\Alices.Library.csproj", "{0902233A-3857-4E5E-99F4-54F3F5E695E5}"
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Bobs.Library", "Bobs.Library\Bobs.Library.csproj", "{56ABE9BB-1373-43D3-B1C5-1526E443AD73}"
EndProject

Visual Studio is quite unpeturbed by this. MSBuild, however, doesn’t like it at all. It reads the file, realises there’s a Project without a matching EndProject, and falls over. For some reason, it always complains that the error is on line 2, even though it isn’t anywhere near line 2.

The fix for this, as you might have guessed, is to open up the solution file in a text editor and manually enter that missing EndProject line after Alice’s project. And that’s it. Or, if you don’t feel comfortable going in and hacking your solution file directly, remember I said that Visual Studio is completely unfazed by this? You can make some sort of small change in Visual Studio that will imply a different change to the solution file: for example, tell it not to build one of the projects in one of the build configurations. Visual Studio doesn’t just change that bit, it will write out the whole file from scratch, so the problem gets silently fixed for you. Which one is less work depends on which one you’re happier doing, to be honest.

That’s the abstruse technical post over for now. Next time I write one, I’ll see if I can find something even more technically obscure.