For many people, the night sky is a calm
serene place, perhaps romantic
Fortunately, it is not.  Every second in the
universe there's a star dying
a supernova explosion.. The universe is an
extremely dynamic place and these
short-lived explosions, they could last
for seconds, for minutes, for months but
they disappear on us. And catching these
flashes of light, catching these cosmic
fireworks,
that's what ZTF can uniquely do.
ZTF will be able to find explosions faster than
we've ever seen before
younger than we've ever seen before, and
rarer than anything we've ever seen before.
The Zwicky Transient Facility was named
after Fritz Zwicky, the astronomer
because he was in fact the founder of
this branch of astronomy, and what it
does is it searches the sky for things
that move or things that change in brightness.
Zwicky in particular began surveying
the sky in a very systematic fashion and
the way on supernovae was really hard
work  - you actually put a photographic
plate in the telescope, expose, bring it
down to the dark room, develop and during
daytime compare. It's hard work! You just
find by your eye.
The universe is so dynamic that you could subtract two
identical pieces of the sky separated by an hour
or a night and see new flashes of light
that weren't there in the image from an
hour before or the night before. Those
new flashes of light in the subtracted
images are what we are after.
The history of the Zwicky Transient
Facility begins really in 1936 at Palomar
and in some very curious way and
some fantastic way, we are coming back to
Palomar, but with bigger and better
machines. We knew looking at the 48-inch
telescope that there's actually a lot
more space there to build a much bigger
much better much more powerful camera.
The problem was to fit a very large
camera into quite a modest sized
telescope so that it does not block the
light that's traveling down from the sky
towards the primary mirror.
It's sort of equivalent to taking a computer and
turning it into a cell phone or a laptop.
You had to worry about every millimeter
of extra space that you used up.
When you're doing all of the assembly
material in a clean room, a lot of work
went into a sequencing to put these very
delicate sensors together in this very
tight space. I was relieved that we
managed to get all of those expensive
devices installed without damaging any
of these semiconductors. Now what we have
is a sensor that's a hundred times more
sensitive, thus taking exposures which
are a hundred times shorter. We have a
robot that changes the filter in a
matter of about a minute; we have a
telescope which slews into position
under computer control and settles in
position within about eight or nine seconds
of command and of the shutter
closing. In the past, we've done this kind
of thing, but at least ten times slower -
which means that we could only find
events which lasted for, say, four days
and now we're getting down to the
timescale of things that only may last a
few hours.
The idea is not going to find a supernova
now and then, but to set up a very large
industrial machine that could discover
dozens of supernovae in a night, and that
makes it possible to start asking more
subtle questions.  And when you have such
a large number, they are always a few
gems out there - each of which then
becomes a unique insight into how nature
makes these explosions.
ZTF will survey the dynamic universe unlike
anything has ever done before.
With its immense survey speeds, ZTF can look at
moving objects in the solar system,
cataclysmic eruptions of stars in our
own Milky Way galaxy, an explosion in
faraway galaxies, perhaps even find electromagnetic
counterparts to gravitational waves and neutrinos.
We have enough resolution in our image to
reach almost the limit that's imposed by
blurring in the atmosphere. So we're
getting all the information there is, and
when you walk up to any one of these images
and you see all of these galaxies all
over the place in these images
It's absolutely mind-blowing, it gives you this
visceral sensation of how vast is the universe
and how complex. And the amazing
thing is that this camera is actually
only looking at the relatively nearby
universe.
