Story of Supernova 2002jy
Mid 2002, I started an automated
supernova search program at my CBA Belgium
Observatory. Although my prime interest clearly is
the study of cataclysmic variable stars, I have been
intrigued by supernovae for many years already.
Combine this with my strong focus on robotic
observing ("automate your telescope to do the tedious
observing work in an unattended manner"), and the
step towards an automated supernova search program
is more or less logical. If you're interested to
learn more about the way I realised the
search program, and the tools I'm using for the
hunting and analysis, click here.
December 18th, 2002 - an evening starts ...
I came home from work
late in the evening of December 18th, after a really
stressful day. The sky was very clear, but the
almost-full winter moon was very dominant. I was
feeling hungry and tired, but decided to start up
the telescope even before dinner, as I was sure this
would relax me.
Normally, I would
point the telescope to one of the cataclysmic
targets of the CBA
network, I belong to.
Unfortunately, the prime target at that moment was
an object far too faint for my telescope, with this
kind of moonlight. The two alternatives were FO Aqr
and AO Psc, but both were already too low in the sky
to start working on.
Next in the priority
queue were 2 variable stars in Cepheus, for which my
Belgian friend Patrick Wils had asked me to do some
observations. However, using an ephemeris that
Patrick had provided to me, it turned out that
both variables were not expected to produce
any interesting activity tonight,
so I had to skip those targets as well.
I therefore decided
to launch my supernova search program SNHunt.
This is a Visual Basic program, written by myself,
that is at the core of my automated supernova search
system. Five minutes
after I had entered the observatory, the telescope
was already slewing to the first target galaxy. I
waited for another minute, to see the first CCD
image appear on the screen of my observatory
laptop, and then left the building, knowing that
the equipment was working fine.
After dinner, my wife
Kathleen and I watched some television. Outside, in
the observatory, the telescope was still doing its
job sweeping from one galaxy to another, taking CCD
images and correcting itself whenever necessary. The
Dashboard of my home
computer, which is directly connected to the
observatory's laptop, was showing 3 green lights,
indicating that everything was working as expected.
the core of my Supernova Search Program. After
loading the list of target galaxies - a simple
Excel file - the program will slew the
telescope from one galaxy to another, instruct
the CCD camera to take the proper exposures,
and consult TheSky to ensure that each CCD
image contains the target galaxy sufficiently
close to the image's center.
Around 10:30pm, I
started screening the CCD images, acquired that
night by the telescope, while more images were still
captured. The screening itself is something I do
manually, using a software program SNViewer, that I wrote myself. It allows to
compare every CCD image with images acquired on
previous occasions. The comparison itself is rather straightforward, due to
the experience I have built up over the previous
months. On average, it takes no more than half a
minute or so, to securely determine if an image has
a suspect star on it, or not.
That 36th image ...
I had been screening images for about half an hour, when
my SNViewer tool brought up image number 36,
showing galaxy NGC 477. Almost immediately, I
noticed a rather bright, star like object to the
northwest of the galaxy, that was not present on my
comparison image. It was also lacking from the
Digital Sky Survey image in my Supernova Viewer SNViewer.
I had seen CCD image
flaws, producing ghost stars, in many of my CCD
images before. But I was convinced that this one
could not be a flaw. So, I pressed the
"Priority" button in my SNViewer
tool. Doing so, the home computer immediately
notifies the laptop computer in the observatory that
a priority target has been identified, and that the
telescope has to move to the target, upon completion
of the current imaging sequence.
Meanwhile, I launched
my Internet browser to visit the Minor Planet
Center's web page for checking the presence of minor
planets in the neighborhood of NGC 477. I was most
surprised to see that no known objects were listed.
image of supernova 2002jy. 80-sec CCD image, obtained on 2002, Dec
18.96 UT, using a 0.35-m f/6.3 telescope and SBIG ST-7
I then launched the International Supernova Network
web page, which gives an up-to-date overview of all
recently discovered supernovae. Nothing about NGC
By the time I had
finished this check, the telescope already had
completed the sweep to NGC 477, and two more CCD
images of the galaxy were waiting for me. It turned
out that the new object was present on both images.
I couldn't believe my
eyes and restarted the whole procedure : was I
looking at the right Digital Sky Survey image, was
the object really not present on a previous image of
mine ? I checked the Minor Planet Center's web page
two more times, did the same with the International
Supernova Network page, and then decided I had done
everything I could do myself to exclude errors or
Time for a
It was close to
midnight now, and I had to find someone who could
confirm my discovery. I have good contacts with a
few supernova-minded amateur astronomers in the US
and South Africa, whom I had asked before to
confirm suspect supernovae. I knew it would take
several hours, maybe even a day, before I would know
the result of their confirmation efforts.
Since it was still
clear outside, I considered a better alternative. My
very good friends Paul Van Cauteren and Patricia
Lampens (the latter is a professional astronomer),
owners of Beersel Hills
Observatory, had already
indicated before they would be happy to confirm any
suspect supernova. So, I decided to give Paul a
ring. A few minutes later, he interrupted an ongoing
observing campaign to try and confirm my finding. He would
ring me back as soon as possible.
tool will load newly acquired CCD images one
after the other. Every image is presented in
MaxIm DL, together with a so called 'reference
image', acquired on previous occasions. In
addition, SNViewer will also load a Digital Sky
Survey image of the galaxy under investigation.
I have included a "blink images"
button in SNViewer, that allows to blink-compare
CCD images (by overlaying them).
Instead of just
waiting for his phone call, which probably would
make me too nervous, I decided to already continue
the analysis of the suspected supernova, assuming
that it really was a new object.
First of all, I had
to determine the position of the supernova
(astrometry). A month ago, I had downloaded an
evaluation copy of Astrometrica, presumably the best
astrometry tool in the world. Fortunately, I had
been playing around with it some weeks ago, to get
used to it. In doing so, I had also downloaded the
complete USNO-A2.0 star catalog. It was quite easy now
to get accurate coordinates of the new supernova,
and its position relative to the core of galaxy NGC
477. I also had to perform photometry, to determine
the magnitude of the new object. This is more or
routine job to me.
Paul and Patricia
rang me back, after they had acquired 9 CCD images of
NGC 477, each 30 seconds exposed, using a V filter.
I hadn't told him the location of the suspect, so we
discussed a while over telephone if the new object
was also present on his images or not. It turned out
to be the case, and Paul emailed me a stacked image,
for a last check.
A message to
the IAU - CBAT
The final step now
was to inform the International Astronomical
and more in particular the Central Bureau for
Astronomical Telegrams CBAT, the clearing house for all
astronomical discoveries. There's a rather strict
procedure for reporting a discovery to the
IAU, which I followed carefully. I checked every
line of my report twice, before pressing the send
button in my email program.
What would come next
? Would the IAU accept the discovery, and how long
would it take before sufficient confirmative
evidence had been collected by the IAU ? I knew from
colleagues, that the whole procedure could
even take a few days. So, I was not expecting any
quick reply from the IAU.
I sent out a couple
of emails to good friends of mine, to announce the
likely discovery. Since clouds had entered the sky,
I decided to shut down the observatory.
Before going to bed,
I did a last check of my email inbox. I was
surprised to already find a reply from Daniel Green,
head of the CBAT, saying that my report was an
independent discovery, and that Ron Arbour in England had also reported the
Great news, that I
decided to share with many friends of the Belgian
Astronomical Association VVS, through their Bulletin
Board. It had taken me nearly 3000 images, since the
start of my automated supernova search program, to
get to this result ! Time to go to bed now ...
The days after
supernova was a real thrill, but what followed
afterwards stroke me even more. I had never
considered that this discovery would attract such a
lot of attention in Belgium.
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical
Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231
Phone 617-495-7440/7244/7444 (for emergency
SUPERNOVA 2002jy IN NGC 477
R. Arbour, South Wonston, Hampshire,
England, reports his discovery
of an apparent supernova (mag 16.3) on an
unfiltered CCD image
taken on Dec. 17.952 UT using a 0.3-m f/6.3
reflector. SN 2002jy is
located at R.A. = 1h21m16s.27, Decl. =
2000.0), which is 46".4 west and
37".6 north of the center of
the galaxy NGC 477. Nothing is present at this
location on a 1995 blue
Palomar Sky Survey plate (Digital Sky Survey).
Further images taken by
Arbour on Dec. 18.713 and 18.719 show the new object at about the same
brightness, and an unfiltered CCD image taken by T. Boles, Coddenham,
Suffolk, England, on Dec. 18.731 yields
mag 16.5 and position end figures 16s.23,
T.Vanmunster, Landen, Belgium, reports his
independent discovery of SN
2002jy (providing position end figures 16s.26,
55".5) on unfiltered
CCD images taken on Dec. 18.96 with a 0.35-m
f/6.3 telescope during
an automated supernova-search program; a confirming CCD image was
obtained on Dec. 18.991 by P. Van Cauteren
and P. Lampens at Beersel, Belgium, yielding V
= 16.0 for the new
object. SN 2002jy was not visible on
Vanmunster's CCD image
taken on Oct. 11.075 (limiting unfiltered mag
17.2) or on 1977 red
Digitized Sky Survey images (limiting mag
The day after the
discovery, I was contacted by astronomers from the
Belgian Royal Observatory. They were very pleased
with this discovery, especially because it was the
first supernova finding in Belgium. One of them
prepared a press release, that was sent to the
Belgian national press agency. When I came home that
first evening, I found my email box loaded with
dozens of mails, with congratulation messages from
all over the world ! What a warm feeling ...
In the afternoon of
Friday December 20th, I got a phone call at work
from a reporter of one of the largest Belgian
newspapers. He wanted an interview, for an article
that would appear in the newspaper the next day. Ten
minutes later, another reporter was asking for an
interview later that evening, at my observatory. I
accepted, not knowing exactly what to expect.
IAU Circular 8035 announcing the
discovery of supernova 2002jy
It is now Saturday
December 21st, and the discovery news has been
announced in 4 national newspapers. I'm getting lots
of emails from people I know and don't know, and
over the past days, my website has received more
visitors per day than ever before.
I have invited some
friends and relatives for a drink this evening.
Tomorrow, things will become normal again ....
Postscript by end
of December 2002
discovery continued to attract attention and on
Monday December 23rd, the national television VRT
visited my observatory for an interview session,
that was broadcasted later that evening as part of a
"light", non-scientific program.
Evidently, the amount of reactions peaked in the
days after ...
I never imagined a
supernova discovery would attract so much public
attention in Belgium - the Christmas period
definitely had some influence on it.