
Astronomers make history in a split second with localization of fast radio burst - Hooke
https://news.ucsc.edu/2019/06/fast-radio-burst.html
======
alanning
"Since ASKAP is an array of 36 dish antennas and the burst had to travel a
slightly different distance to each dish, it reached each one at a slightly
different time."

“From these tiny time differences—just a fraction of a billionth of a
second—we identified the burst’s home galaxy and even its exact starting
point..."

Simply amazing that they can get such precise measurements from so small a
differential in distance.

~~~
umvi
> Simply amazing that they can get such precise measurements from so small a
> differential in distance.

How do they know the billionths of a second differences aren't due to the
radio waves travelling through pockets of air that have slightly different
densities/temperatures/moisture/refraction properties?

That just seems like incredible error tolerance

~~~
ajford
A lot of the atmospheric affects are on longer timescales than the sampling
times, which means they can be calibrated out.

Most observations of this nature (interferometric observations) will point at
a nearby calibrator source (usually a well characterized quasar or other
"point source" star/object), and an atmospheric noise model will then be
constructed based on this calibrator to apply to each dish to minimize/account
for the atmospheric influence.

This is often repeated periodically to account for changing weather over time.
And on top of that, a benefit of the location chosen for ASKAP was relatively
dry air (being in the western desert climate of Australia).

~~~
cmendel
That's really interesting! Would you be able to point me towards some
resources to learn more about this?

~~~
ajford
A lot of it I learned when I studied Radio Astronomy in college (my major).
I'm a little rusty now after about 7 years.

However, here's a few resources I remember and was able to dig up.

1) A presentation from Max Plank University, which has one of the strongest
radio astro programs around: [https://www.mpifr-
bonn.mpg.de/3244052/IMPRS_BB_HRK5.pdf](https://www.mpifr-
bonn.mpg.de/3244052/IMPRS_BB_HRK5.pdf)

2) Presentation from ASTRON, an interferometric array in the Netherlands, part
of the Netherlands Institute for Radio Astronomy:
[https://www.eso.org/sci/meetings/2015/eris2015/L6_Heald_cali...](https://www.eso.org/sci/meetings/2015/eris2015/L6_Heald_calibration.pdf)

3) George Moellenbrock's slides from the 14th Synthesis Imaging Workshop
(hosted by the National Radio Astronomy Observatory) is pretty detailed on
calibration specifically:
[https://science.nrao.edu/science/meetings/2014/14th-
synthesi...](https://science.nrao.edu/science/meetings/2014/14th-synthesis-
imaging-workshop/lectures-files/MoellenbrockCalibration2014_FINAL.pdf)

There was at one time a video of the last link, but it appears the hosting
site is no longer live. There are other lecture slides on radio interferometry
available from the Synthesis Workshop site:
[https://science.nrao.edu/science/meetings/2014/14th-
synthesi...](https://science.nrao.edu/science/meetings/2014/14th-synthesis-
imaging-workshop/lectures)

------
SiempreViernes
A more interesting account by two of the members of the project that did the
novel bit: [https://theconversation.com/how-we-closed-in-on-the-
location...](https://theconversation.com/how-we-closed-in-on-the-location-of-
a-fast-radio-burst-in-a-galaxy-far-far-away-119177)

Also, the full science paper, might be decent too:
[https://science.sciencemag.org/content/early/2019/06/26/scie...](https://science.sciencemag.org/content/early/2019/06/26/science.aaw5903)

------
perlgeek
They made history in a split second, presumably after spending decades on
building the infrastructure and gathering all the prerequisite knowledge.

The first observed binary black hole merge signal was probably also quite
short (I'd wager less than a minute, possibly even less than a second), and
many of us have read about how much effort that one took.

------
imroot
This has been happening since 1999 by the NAAPO (the same group who ran the
"Big Ear"). They had a cluster of helix antennas being fed into a VA Linux
Systems Hardware Cluster doing analysis on radio astronomy events:

[http://www.naapo.org/Argus/docs/docsmenu.htm](http://www.naapo.org/Argus/docs/docsmenu.htm)

I volunteered there from 2004-2008. I believe that the cluster is still active
today.

------
YeGoblynQueenne
That's great news- but I'm confused by the following analogy:

>> "It's like looking at the Earth from the Moon and not only knowing what
house a person lived in, but what chair they were sitting in at the dining
room table," Bannister said.

What are chairs and dining room tables by analogy to galaxies and in the
context of fast radio bursts?

Could someone please clarify?

~~~
Zoo3y
Further in the article they mentioned telescopes have to be placed certain
distances apart to calculate differences in radio wave arrival by billionths
of a second. These differences gives them granular placement within the galaxy
(I'm assuming the analogy is referring to arms, stars, planets, etc.)

------
mrybczyn
cached:
[https://webcache.googleusercontent.com/search?q=cache:89RLX_...](https://webcache.googleusercontent.com/search?q=cache:89RLX_fqiIMJ:https://news.ucsc.edu/2019/06/fast-
radio-burst.html+&cd=1&hl=en&ct=clnk&gl=ca)

------
titzer
Amazing they can measure timing differences less than nanoseconds and use them
to localize phenomena millions or billions of light years away. And I can't
reliably measure whether I made my program 1% faster or not :(

~~~
Cthulhu_
I bet you could, but you need more measurements and statistical analysis. Keep
in mind that a lot of these astrological measurements - and a more notable
recent example is the black hole visualization - are not based on direct
measurements, but statistical analysis on huge datasets.

~~~
SiempreViernes
It is spelled > _astronomical_ < measurements, you squidface!

~~~
gmfawcett
Well, it still stands as written, as long as you're one of those big-data
astrology people.

------
joncp
This as well as the recent imaging of the M87 black hole are both phenomenal
feats of signal processing. Is this the new normal for astronomy?

~~~
petschge
Radio astronomy has always been pushing the frontier of signal processing.
Gamma ray telescopes also need large amounts of data crunching. Until recently
optical telescope where much more about instrumentation than data processing.
But even that is changing, e.g. with small and mid-sized robotic telescopes
that automatically search for transients and schedule their own follow-up
observations.

------
elorant
One thing I don't understand from the article is whether they took into
consideration galaxy movements. Given that this is a 3.6bn years old signal
wouldn't it be safe to assume that the place we can pinpoint now as the
originator might not be the same it was back then?

~~~
gilbetron
The radio signal is just as old as the light (both being EM), so they align
(more or less).

------
nisten
Galaxy: Honey I'm 3.6 Billion light-years away.

Scientist: I'm getting mixed signals I don't know what to do anymore.

------
segmondy
Amazing engineering

------
danschumann
My confirmation bias says it's aliens. Who moved my car keys? Aliens.

~~~
jimmcslim
If an Albecurrie Drive is feasible, could an FRB be a sign of operation?

~~~
dylan604
Only if someone was around to hear it

