[time-nuts] Chasing the "BOAT"

[Graham / KE9H]

"although it doesn't appear to perturb GPS reception, it is evident at VLF,
so I'm interested to hear any reports of detection of GRB221009A via WWVB."
-- TvB

I am located in Austin, Texas.

I have been developing an SDR VLF WWVB receiver running on a fast
microprocessor, that Tom was aware of, and he was fishing for some results.

I was running a logging receiver, but my logging program silently quit, a
few days before the event, and by the time they announced it, it had also
rolled out of my command line buffers.

So the VLF event of the century, and I missed it.

The logging program runs in Python 3.9, on a Raspberry Pi-4 / Ubuntu 22.04
LTS, powered from an UPS.

My logging program watches two serial ports in separate threads (The TICC
and the WWVB Receiver), combines and merges the data in the main loop, then
once per minute, writes the data to disk (buffer), and also prints to local
command line.  I flush the disk buffer every ten minutes to limit data loss
if something crashed.

How it could stop writing to disk, but still keep printing to local command
line, without Python throwing an error makes no sense.

It appeared to be working fine on the local command line output.

I think I had done a Linux update, one of those that says you don't have to
reboot, but it appears that Linux stopped writing from Python to the disk,
but didn't reflect an error back through Python.

Note to self: Always reboot everything after a Linux update.

But I also have a development receiver sharing the same antenna through a 0
dB active splitter.  When I am not developing, I let it run just to test
the software, and I view and log the command line with Putty.

So, I do have logs of RF levels during the "BOAT" event, just not with the
TICC time data.

But the plots show a normal day. Not so much as a wiggle at the time of the
event.

See "2022_OCT_9 Annotated.pdf" attachment, below.

So, why?

Well, it appears that the "BOAT" event originated near the constellation
"Sagitta" (The Arrow).  (Not to be confused with Sagittarius (The Archer)).

According to
https://skyandtelescope.org/interactive-sky-chart/
"Sagitta," at my longitude, set at about 3:30 AM CDT, so was about five
hours below my western horizon at the time of the event.

To see an RF level change, you need to illuminate the "D" layer for the
path between the transmitter and receiver, and you have to be in daytime
"D" layer propagation mode, and not the "F" layer nighttime propagation
mode.

I found a global map plot of the event illumination footprint at
https://spaceweatherarchive.com/2022/10/17/powerful-gamma-ray-burst-made-currents-flow-in-the-earth/
See the green colored global map about the middle of the article.

It shows the area illuminated was roughly from eastern Australia to west
Africa, including Europe.

The narrative discusses a VLF receiver in Tasmania that listens to India,
NW Australia, So. Korea, and WWVB.  They saw the RF levels wiggle on the
three paths inside the illumination zone, but not on WWVB, whose path was
totally outside the zone.

Editorial comment: This was an event that is variously reported as 1.9 to
2.4 Billion light years away that provides the same radiation levels as a
medium solar flare 8 light-minutes away. What if it was closer? We have
more to worry about than big meteorites.

--- Graham
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