JD 2460430.385620, date 2024 Apr. 29.88562 mag 7.118

JD 2460430.385389, date 2024 Apr. 29.88539 mag 8.835

JD 2460430.385046, date 2024 Apr. 29.88505 mag 11.250

JD 2460430.384698, date 2024 Apr. 29.88470 mag 9.890

Reporting magnitudes above 8.0 has been explicitly discouraged unless you're really sure.

Either someone (observatory code not given above) is going to be very embarrassed, or a lot of BIG telescopes are dropping their metaphorical cookies and slewing to "TOO".

Am I over-cooking one datum? Good question. But ... the discouragement about reporting magnitudes above 8 ... I have to trust the observers to be sane. Hit the "submit" button.

JD 2460430.385620, Date 2024 Apr. 29.88562 mag 7.118

JD 2460430.385389, Date 2024 Apr. 29.88539 mag 8.835

JD 2460430.385046, Date 2024 Apr. 29.88505 mag 11.250

That looks like it has "gone". And I'm going to STOP interrogating the database, because the "big boys" need that access. And that is precisely why I didn't post a direct link into the database. The "Slashdot Effect" may be history, but now is not the time to fry the servers.

The "alert" messages were very explicit about, "chill out below M=8". Someone has hit the Big Red Button.

This one will presumably do that eventually.

Welll ... It is quite sensitive to the mass. And to the metallicity.

Which uncertainties are precisely Why this "close", "well-understood" example is important. If (unlikely) it goes exactly per Group1's expectations. then Group2 will disagree, strenuously.

If (unlikely) the "bang" happens on 2024-05-01.00001, then the disputes will start at. approximately. 2024-05-01.0002.

And, as normal - has it "gone"? JD 2460430.385620 date 2024 Apr. 29.88562 mag 7.118.

OK, has it gone? The alert has talked, repeatedly, about RED FLAGging a brightness above 8.0, and 7.1 is a LOT above 8.0.

Has it "gone"?

I've got to go check. Then STOP interrogating the AAVSO database, because people with jobs to do, have jobs to do. This is why I didn't give a direct link ot the active database.

What were the previous reports? JD 2460430.385389 date 2024 Apr. 29.88539 Mag 8.835 variation 0.006
JD 2460430.385046 date 2024 Apr. 29.88505 mag 11.250

That is very suggestive.

Actually, Wiki covers this. The constellation is Corona Borealis, it's genitive is, indeed Coronae Borealis.

I may have been sloppy in my typing - I know of the convention, but never having formally studied Latin, it doesn't appear in my internal spell-checker.

Now, which Duolingo course to do this evening - Swahili, French (revision), German, Spanish (learning beyond my schooling), or Russian? Oh, I forgot Portuguese - but that's so similar to Spanish that I can function in Portugal already.

This is different from an Ia supernova, during which a neutron star captures enough gas from a nearby star to collapse into a black hole.

That depends on the nature of the underlying white dwarf - it is hypothesised. A CNO (Carbon- Nitrogen- Oxygen) white dwarf is thought to disrupt completely by everything fusing in seconds. A ONe(Mg) (Oxygen- Neon- [maybe Magnesium]) white dwarf on the other hand is thought to disappear down the plug hole of forming a neutron star then (possibly) a black dwarf.

Which is theory - and subject to experimental confirmation. Or disputation. And it looks as if Nature is going to go do astrophysicists (and bomb-designers) the courtesy of doing the experiment for us. And at an un-distressing range too. You probably wouldn't want to do this experiment in, say, the Alpha Centauri system.

Type this, that or the other SNs are spectroscopic and light-curve classifications ; whether they map neatly onto the actual underlying mechanism is another point of theory - subject to experimental confirmation (or disputation). If this event gives the wrong answer ... there's a lot of re-writing of theories to be done. And what did Feynmann say about theories that disagree with experiment?

(There will be so much ink shed over "what was the nature of the precursor in T.CrB?" if it gives the wrong answer. But probably more ink, if it gives ambiguous answers.)

With a (probable ; argued, but not demonstrated) sequence of 10 eruptions for this example, the eruption probably ejects more than 90% of the accumulated mass, but that's me calculating on the back of a thumbnail, not an astrophysicist thinking it through in detail.

Which is precisely why Nature's experimental run needs watching with as much data-collection effort as can be swung in the right direction, in the first few hours.

While I think about it, what's the latest score? JD 2460429.960301, date 2024 Apr. 29.46030, magnitude 10.0391 - hasn't gone yet.

... nstead of using diesel power to drive the wheels directly it drives a generator to create electricity to power the wheels.

And thats more effiicient how exactly?

Actually, much more efficient.

Because engines are terrible - the reason we have gearboxes is because you cannot run an engine at multiple speeds efficiently. That's why you have 6, 8, 10, 12, 18 gears - you need to keep the engine in a VERY small power band otherwise it's running at speeds that just are not conducive to efficient operation.

Of course, you're driving down roads going at whatever speed you like - and electric motors have a very wide power band, which is why basically any EV has a single speed transmission (or direct drive). It's also why EVs have very good low speed torque.

So you can hook the engine up to a generator, run the engine at its optimal speed, and generate a fixed amount of power. That power can be supplemented by batteries if you need more than what the engine and generator can provide, and it can be diverted to charge the batteries when you need less.

This also means you don't need a 2500 HP engine in a semi - you can run a much smaller, more efficient 1200HP engine - because if you need peak loads, you run engine plus battery for the litlte time you need it. You're not buying a larger engine than you need for the few times you need it. This makes the whole thing even more efficient.

When Y2K happened, people came up with all kinds of hacks to predict dates. Knowing how cheap companies are, a lot of that stuff is likely still running unchanged. I remember back then a lot of times we'd say "this shit won't be an issue for a couple decades, it'll get replaced or rewritten by then"... you know when you're young it feels like you won't get old ever .. like a decade will take forever to go by.

Yeah, that's what people said back in the 60s and 70s - that the code wouldn't be running in 1999. Of course, if you're fixing 30 year code back then, what's another 20 years to it? If the code was from the 70s, you were fixing it in the late 90s, there's a high chance it'll still be running in the 2020s. Code that's lasted 30 years already doesn't really check changed all that much.

I'm sure a lot of C library functions are getting up there in age as ewll. We still have all the nice unsafe C library functions like strcpy() and such to this day even though we knew they were unsafe over 20 years ago. It just hangs around.

However, the problem with that model is that there is no universal "now".

As Einstein pointed out with his demolition of the concept of simultaneity in his 1905 paper on ... it was the "Electrodynamics" one, wasn't it? Been a while since I read them.

If SR is true (and it agrees with experiment to high precision, until you get into the realm of GR), then there is, indeed, no "now" except for "here".

What's the deal, is it just broadcasting re-runs?

That is, indeed, part of the Big Question (as DrBecky considered, briefly, in her video).

These systems (large stars feeding mass onto an orbiting white dwarf are thought to be progenitors of the "type 1a supernovas" which are our most accurate "standard candles" for investigating the distant cosmos. Hence, "dark energy" - but not "dark matter" - hangs on understanding this process well.

One of the big outstanding questions in the field is whether the "metallicity" of the progenitor star meaningfully affects it's peak brightness or "rise time" (time from first-brightening to peak brightness), and decay time (fading rate of the supernova). As (possibly) the closest example of such a system, you can see the importance of observing this system as closely as possible. This is (will be) the first opportunity we've had to see one, close up, with warning, since we had detailed science on thermonuclear explosions. A lot hangs on understanding such systems as well as we can.

One of the arguments is that repeated eruptions like this cause "metals" (nuclei heavier than helium/ lithium) accumulate from one eruption to the next, until there are enough to trigger the catastrophic destruction of the entire star, instead of a (relatively - see comment about a hydrogen bomb the size of the Earth) gentle re-surfacing of the white dwarf.

Another continuing argument is over the nature of the progenitor white dwarf - is it composed primarily of carbon, nitrogen and oxygen nuclei (a "CNO" white dwarf), or is it composed of oxygen and neon nuclei (an "ONe" white dwarf, possibly with magnesium for ONeMg). Understandably, this may affect the resulting supernova, in terms of peak brightness and decay time (and possibly rise time, but for unpredicted events, that's not a huge amount of use. Probably.)

How many "re-runs" are needed to accumulate a "trigger mass" of eruption debris? Nobody knows. From the eruption history of this star, it has probably done it more than ten times previously, but at 80 years per data point, how significant that is, nobody knows.

A lot hangs on understanding these "standard candles". For example, in theory the whole paradigm of "dark energy" could be upset by understanding these eruptions, stellar systems, and the (probably) resultant supernovae better. It's unlikely to go that far, but whether the universe is 75% "dark energy", or 25% is more plausibly open for re-evaluation.

This "re-run" is probably a bigger deal then seeing "I love Lucy" yet again, even for a hungry, lust-sick alien.

that's actually not *that* bright.

As I said in my original submission (and EditorDavid waved the blue pencil over),

the 50th (or even 30th) brightest star in the sky

.

Making the (optimistic?) assumption that the average Slashdot user can count to 11 without removing pants or socks, that means that the affected "quadrant" (one quarter of the above-horizon sky) would go from having 4-to-6 stars this bright to having 5-to-7 stars this bright. Not going to knock your socks off, but should be visible to anyone who has thought enough to RTFA, and then curse the clouds.

I can only hope the effing cloud cover is going to finally break a bit in my area,

Yeah, but you sent in an order for a new telescope/ eyepiece/ filter last night, and it's delivery window will coincide with the eruption's visibility from your part of Earth. Definitely your fault. I've already screwed it for all Slashdot readers. Standard Operating Procedure.

(Since cursing the editors is a Slashdot pastime, definitely, EditorDavid left those numbers in from my submission, as well as adding other sources.)

Why does everyone seem to think RISC-V has anything of importance?

There is nothing of value in the RISC-V architecture.

There are no trade secrets or anything special in RISC-V. It's just an architecture.

All the "magic" in RISC-V is the same "magic" in ARM, or x86/x64 and other stuff - it's in the implementation.

Nothing RISC-V has relates to the implementation. There are companies with interesting implementation like SiFive and others who have their own silicon. But that's it. RISC-V is not like ARM - you can't go to RISC-V and get a complete synthesizable CPU core from the get-go. It's not how it works there.

You can find open implementations of a RISC-V core - there are several open-source ones, but there are many closed implementations as well.

There's only 2 documents describing the ISA, a software implementation for testing purposes, and a formal description of the implementation.

Some people in my company were exploring RISC-V. They didn't realize you didn't get an implementation like ARM. I told them you could license an implementation, or you could do it yourself (which did appeal to them as that way they could "own it all"). But to do that means you had to design the CPU yourself, as well.

The only concern might be if China is using a RISC-V implementation that the US has blocked, but most RISC-V implementations aren't that performant to be a concern