Bright Possible Supernova Discovery

[PeterM]

Hi all,
As per usual the Backyard Observatory Supernova Search (BOSS) team are happy to provide IIS members with breaking news.

Last night around 9pm, Greg Bock (of the BOSS collaboration) discovered a possible very bright supernova in a far southern galaxy IC4901 in Pavo.

By the time Greg was able to blink the image against his reference image the galaxy had dipped below his horizon. He rang me at 11pm to see if I could get a confirming image. I had just closed the observatory due to complete cloud cover, but thought what the heck, I will move the 'scope to the galaxy (now way over in the southwest at 28 degress altitude)and just start imaging in the hope of a break. Well that's what happened, a small break allowing enough time to get a confirmation image. While Greg and Colin Drescher worked the numbers (position magnitude, offset etc) the sky cleared enough for me to get a better image at only 20 degrees altitude. The object was reported as a possible supernova (PSN) on the CBAT TOCP Page / Bright supernova page, you will see it listed as unknown discoverer at this stage until all the formalities are done http://www.rochesterastronomy.org/supernova.html
Designated PSN19542141 -5842390 the position (J2000) is 19 54 21.42 / -58 42 39 and its magnitude 14.5r which means it should be visual for 12inch scope owners (Hi Ron Knight!).
Now its only a PSN until the professionals get a spectra and here's where all our hard work is paying off. We have a collaboration with a professional astronomer studying supernova and she is going to try to get a spectra using one of the 6.5m Magellan 'scopes at Las Campanas Observatory in Chile in the next several hours. Once this is done she will send it to the IAU and it should then have an official designation and be released on a Central Bureau Electronic Telegram (CBET). We also have professional collaboration with the SALT telescope astronomers in South Africa and no doubt being bright will be of interest to them.

So there's the report, but what about the guy who discovered it, Greg Bock. As many know Greg and I work alternate Saturdays at Sirius Optics, more for the love of it than an extra income to pay for astro toys. Greg has been a very keen supernova hunter for many years and clearly my successes and indeed much of BOSS would never have happened without the groundwork, hard slog and assistance he laid down over many, many years. We both had great excitement in confirming some of Bob Evans visual discoveries years ago. Greg is also, like Stu Parker an absolute perfectionist superb astro imager.
You may not be aware Greg has one of his images used to pan across the sky in the Carl Sagan Cosmos DVD set as well as having a huge blown up image of Crux on display in the Carnegie Institute (I think its that one) and lots of other images on book covers etc. Now Greg has never given up on finding his own supernova, literally tens of thousands of images - not of nothing, but meticulously building up a library of reference images that last night delivered huge rewards.

I thank and congratulate him on his persistence and help. Goes to show what keen amateurs can achieve.

I will keep you posted on the outcome of the spectra and look forward to someone spotting it visually. Greg will no doubt respond and place an image here later today, well I don't want to steal all his thunder.


PeterM.

[DavidTrap]

Well done team - another one bites the dust!

DT

[Park123]

This is one of the best parts of Astronomy is to see a friend achieve something he has wanted for so many years.
Greg has been key part in so many of mine and Pete’s and Brendan’s Supernova discoveries since the group was formed a few years back and way before that has done alot of work with Bob Evens confirming his Supernovae. But he always wanted to get that one of his own....got it now after so many years of trying and seeing others getting them. What about that for staying power!!!
I woke up to all the excitement at 4am as all this happened while I was asleep (dam 3 hour difference).I got yelled at from My wife Lynn who was by this time in the Kitchen getting ready to go to work as I was still in Bed(as usual) "GREGS GOT ONE "as she read the SMS and emails on the phone.
So all of New Zealand breaths a sigh of relief.
Well done mate a great find. A great bright SNe in a really nice galaxy. Great for you and for BOSS
Looking forward to seeing some of those images you will be taking over the next few weeks

The only thing I am really annoyed about is that I won’t be able to share a port or two with you over this. But I will have a couple for you over here. I hope the wait was worth it
Very happy for you ......enjoy
Stu
BOSS-Backyard Observatory Supernova Search

[h0ughy]

Congratulatons Greg, and the rest of the BOSS team

[SkyViking]

Congratulations, great work! :D

[firstlight]

Good luck Greg, and thanks for the report Peter.

[Greg Bock]

Hi Guys,
well, fingers crossed that this does turn out to be a new supernova! Only a good spectrum can prove it, so hopefully, that won't be too far away.

Thanks for the generous thoughts above, and your ongoing and stoic support. It's great to work in such a supportive and helpful team like this, particularly when we can provide some value back to the professional work.
I have been imaging galaxies for more than 10 years and taken more than 50,000 images to finally discover one for myself, rather than find a pre-discovered one, or an asteroid, so i hope it's also not the last for another 10 years!!

I have attached a jpg copy of IC4901 and the suspect, and would like to hear if anyone can see it visually too. At mag 14.5, it should be in the range of moderate scopes (say 12" at least) under dark skies.

[iceman]

Congratulations Greg and the rest of the BOSS team.

Amazing work and I hope it proves to be what you want!

What a thrill - the anticipation must be killing you! :)

[Greg Bock]

Thanks Mike, yes, as usual it was a great team effort.

After I realised the object was new, I checked for asteroids, variable stars, and previous discoveries in that galaxy, and then notified Peter who managed to get a second image between thick clouds to confirm that it was a real object and had not moved. Meanwhile Colin and I did the astrometric analysis for position and magnitude, then Col posted the TOCP, and I prepared the verbose report for the CBAT.
The only things that didn't play ball were the clouds, and my laptop that blue-screened just before I sent the CBAT report!! That cost me another hour between 12:30am and 1:30 am preparing another report for CBAT!

The really unusual aspect of this discovery is that Stu slept through the whole thing!. I guess being 3 hours ahead of us can get in the way a bit. He missed out on the fun and excitement for a change....

[astroron]

Congratulations Greg,and the team :thumbsup:
At last one for yourself after all these years,the first of many I hope :DI will attempt a visual report as soon as the clouds go away.
Cheers :thumbsup:

[madbadgalaxyman]

Congrats, Greg, on the candidate supernova discovery.

It can be really hard to find good-resolution reference images of far southern IC catalog galaxies.....indeed, I would go so far as to call them the least studied Bright Galaxies in the sky (some of the bright non-NGC/IC galaxies with ESO designations..... are also virtually unknown)

I have two images of IC 4901 on file, and here they are.
(IC 4901 was also imaged in the H-alpha bandpass, in the survey known as SINGG)
(The NED database (//ned.ipac.caltech.edu) also contains various images of IC 4901.)

- Robert

102479

102480

[Paddy]

Congratulations Greg, great news. Fingers crossed for some clear skies sometime soon to have a look!

[Greg Bock]

Thanks Robert and Paddy,
yes, thanks for those images, I have had trouble locating good images of it, so I guess I'll have to take some for myself.

The other good news is that a spectrum taken at Las Campanas at La Serena in Chile today now confirms it to be a young blue type II supernova, so early light brightness measurements are welcome too.

[madbadgalaxyman]

Greg, Mr "SN Cracker",

I continue to "recoil in fear and awe" at the sight of the new supernova you discovered!

Here is a (continuum subtracted) H-alpha image of IC 4901 which was made by the southern Ha imaging survey called SINGG. The image is at a logarithmic scaling, and there is also a Broadband Red Light channel which is added to it, displaying here as blue.

102500


H-alpha images of southern galaxies made in the SINGG survey can be found at:

http://sungg.icrar.org/home/portal

[PeterM]

Now that we know this to be a very young Type II event (core collapse of a giant star) it is very likely to brighten, making it visible possibly in say 10inch scopes, maybe less. The galaxy is approx 101 Light years away and a very fine target for astroimagers. Robert (Madbadgalaxyman) maybe able to give us some indication of how bright this event could become.

There are very few Supernova each year that do become visual objects so here is a challenge to the eyeball amateurs out there.

Use the image in the above posts and spot the "supernew star" then ponder what happened to it 100 million years ago. The incredible power that was unleashed. As the light enters your eye think of what was happening here on Earth when that light left the doomed star and how far we have come. Think of what has happened to that star over the last 100 million years and how from its destruction, the new elements created in the inferno may now be in the throes of forming a new, very different star. A process that at least in our case led to an amateur astronomer on a planet circling a distant much smaller star, roll back the roof of his observatory one starry evening, point his telescope at a distant galaxy and be the first out of 6 billion to view an event that happened 100 million years ago.
I just love it.
PeterM.

[madbadgalaxyman]

Thanks, Pete, for the interesting comments. It is interesting to hear, again, from an old colleague.

If my previous experience with the many brightish IC galaxies in Pavo is anything to go by, data on this galaxy will be hard to come by.
I will have a look at how bright this SN might become (after I have got over yesterday's "data overload" from considering two dozen papers and a hundred images about M31 !!)

From the available redshift, this galaxy is going to be at least 50 percent further away than the Virgo Cluster of galaxies, so the SN at maximum probably won't burn out the observer's eyeball.

IC 4901 seems to be in a remarkably low density region of space, at least judging from the fact that few galaxies in Pavo share its redshift (and distance). Most of the bright galaxies in Pavo are in the supercluster at about twice the distance of IC 4901.
But the "Pavo" effect of scant available data means that there are actually a lot of galaxies in this constellation for which even simple redshift data is not available!

[Greg Bock]

Hi "Recoiling Robert", and everyone else above....
Robert, thanks for the Ha image above, and the link to the SINGG survey.
It will be interesting, if I can do it, to overlay the Ha image with my discovery image to see if there is a nice correlation between a particular Ha region and the supernova.

I received confirming advice early today from Las Campanas Observatory about the spectrum. Our friends there were very quick to willingly help out as much as they could by interrupting their planned schedule and recording the spectrum. They used the 6.5m Magellan II Clay telescope to identify the SN as a young type II P, where the 'P' stands for a 'Plateau' type. This means that the light curve will decrease more slowly over time than other type II L's, and type 1's,so it will be interesting to image it and develop the light curve over the next few months.

The spectrum was also recorded earlier today by the NTT team at La Silla, and agrees with the type IIP result, fantastic.

We have some clear weather coming soon I hope, if so, I will also try to obtain some hi-res images of the SN too.

[tilbrook@rbe.ne]

Congratulations, on the discovery!

How many hours have you put in for the discovery?

Cheers,

Justin.

[Robh]

Great stuff! Congratulations Greg.

It's been interesting and exciting to follow the progression of events in confirming the supernova event.

Regards, Rob

[Ric]

Congratulations Greg, I agree this has been a great thread to follow and read about how it all unfolds.

Cheers

[Greg Bock]

Thanks Justin, Rob and Ric.

Yes, its been quite an exciting ride for the last day and a half. This is, of course, always the case whenever the BOSS team makes and submits a discovery, but it's been heightened for me this time because this is my first discovery contribution.

Normally when Stu or Pete have made discoveries, I am doing the confirmation images, analysis, and/or reporting, so it's good the have the shoe on the other foot for a change!!

As I said at the BOSS presentation at the Australian Imaging Conference in June this year, with all the technology that's available to us these days, it's a great time to be an amateur in this field. There are so many resources, information, communications, and support available for doing this and contributing back to the science. Very satisfying indeed.

[CometGuy]

Congratulations Greg, what a tremendous effort to finally bag one!

Terry

[madbadgalaxyman]

Peter asked how bright this supernova is going to get.

This is a tough question in the absence of a reliable distance measurement for IC 4901. There have been a couple of individual estimates of the distance of IC 4901 using the Tully-Fisher method, which unfortunately is no more accurate than using the redshift of a galaxy to estimate its distance. In fact, the two Tully-Fisher distance determinations are highly discrepant.

Sadly, IC 4901 has had very little study by professional astronomers: it gets just a brief mention in a handful of papers. This situation is exactly as I would expect from the poor results of my previous searches for info about various southern IC galaxies!

In the circumstances, it might be best to estimate the distance of this galaxy from its redshift, which is 2038 km/s in the Local Group reference frame (according to the NED database). Assuming a Hubble Constant of 73 km/s/Mpc one can then use this redshift to estimate that the distance is 28 Megaparsecs ( = 91 million light years) .

The other parameter that we need in order to estimate the probable peak magnitude of this supernova is its luminosity (absolute magnitude), which introduces further uncertainty. As I am unfamiliar with the literature on supernovae, my most recent information about the absolute magnitudes of Type II-P supernovae comes from the year 2002 (D. Richardson et al., (2002), AJ, 123, 745) and it is an average of the luminosities of a small number of these supernovae. Richardson et al. find a mean Blue absolute magnitude of -17 for Supernovae of type II-P, but they also find that the luminosities of the individual II-P supernovae events occupy a wide scatter between
B absolute magnitudes -16 and -18

Assuming a peak absolute B-band magnitude of -17 for this supernova, and a distance of 27.9 Megaparsecs (a distance modulus of
m-M = 32.23), and a total extinction (the internal extinction within IC 4901, plus the foreground extinction from the Milky Way) of 0.6 magnitudes, we can then use the standard equation for distance modulus and absolute magnitude to estimate a peak apparent blue (B-band) magnitude for this supernova of 15.8, which is quite faint.
If the supernova was absolute blue magnitude -18 in luminosity, it would probably end up being closer to Blue (B-band) magnitude 14.8

Given the uncertainties as to the distance of this galaxy and the luminosity of this supernova, not to mention uncertainty as to the precise amount of dust extinction, a peak apparent Blue magnitude of 14.6 to 16.3 can be considered a ballpark estimate.

cheers,
mad galaxy man

P.S. the amount of extinction from dust within the host galaxy and within our own Milky Way galaxy can make a considerable difference to the apparent magnitude of a supernova. I assumed only 0.2 mags of foreground extinction, together with a further 0.4 magnitudes of dimming of the SN's light coming from within IC 4901 itself. The foreground extinction from our own Galaxy can be calculated with reasonable accuracy, but the extinction of a supernova's light caused by the dust within its host galaxy will be unique for every observed supernova.

I can't put a figure on the distance uncertainty regarding IC 4901, but I assume that it could make at least a 0.3 magnitude difference to the observed magnitude of the supernova.

If, for instance, I assume that the SN is more luminous than the average for its type (in this example, assuming that the SN is -18 abs. magnitude), minimal dimming of the SN's light by dust (say, 0.4 blue magnitudes of all-sources extinction), and a 15 percent closer distance for the host galaxy (say 77 million light years), then the apparent B magnitude of the SN at its peak will be B = 14.3 magnitude.

[gregbradley]

I imaged this one last night with my Planewave CDK17 and Microline 8300 camera. The luminance is not bad but the colour data not so good yet.

A bit of cloud came over during the green sub.

http://www.pbase.com/image/139036871

Greg.

[madbadgalaxyman]

Hi Greg,

is that magnitude secure? Also, what bandpass is it in?
(B? V? R?, visual?)

cheers, Robert

[strongmanmike]

Congratulations Greg, fantastic story mate! well deserved discovery!

How exciting it must be for you guys and I like Peters little description of what it is that we are really seeing, it is well worth the itruspective thought as it must be easy to get held up in the idea that it is just another dot in a fuzzy blob.

Well done BOSS team :thumbsup:

Mike

[madbadgalaxyman]

I Absolutely agree, Mike. We should remember that the "dot in the fuzzy blob" is all that is left of the light of this fearsome and awesome supernova after that light has traveled some 90 million light years through space.

Some people coming to this thread for the first time might wonder, in fact, why all of us are making such a great fuss about this tiny dot of light seen in a distant galaxy.....the reason is that even a modest supernova explosion puts out about a billion times as much light as our own Sun!

[Rob_K]

CBET 2868 : 20111022 : SUPERNOVA 2011gv IN IC 4901 = PSN J19542142-5842390

Congratulations Greg & the BOSS team!

Cheers -

[Greg Bock]

Hi all,
Thanks for the CBET details Rob, I'm out having coffee with Kath right now, so it's harder to reply properly from the iPhone, but I will get back to this thread later.
To all who have posted here, great posts guys, keep them coming, it's wonderful to have the opportunity to share this with such a supportive astro-community.

Greg

[Paddy]

Just managed to observe this SN in brief gaps between the clouds. Quite distinct in the 16" scope at 250X. Very exciting to see a star exploding 90 million light years away and 90 million years ago! Report to follow in Obs report section.:)

[madbadgalaxyman]

Congrats, Paddy...you must be one of the very first people on the planet to see this object with the eye, as this SN news has not gone far beyond the confines of this thread!

We are getting a "back row seat" when viewing this celestial show....the light has travelled a bloody long way to reach your eye.......this is probably just as well, as I wouldn't want to be anywhere near this supernova.....

The galaxy itself looks low surface brightness in the images, with the only relatively bright part being near its centre in the form of a small bar that is surrounded by an indistinct ring structure.

[PeterM]

Hi Robert,
It was 14.5R measured by Colin Drescher. I know he uses Astrometrica nad several other programmes.


And Paddy, yes indeed you are the first we are aware of who had his eyeball exposed to this Supernova, congratulations!
PeterM

[madbadgalaxyman]

Thanks, Pete, for the info about the type of magnitude.

If the SN was observed to have an R-band (Johnson-Morgan) apparent magnitude of 14.5, then what we need to derive for visual observers is its V-band photometric magnitude, which approximates its visual magnitude.
For instance, if the V minus R color of a type II-P Supernova is x, then its V-band magnitude equals (x + the R-band magnitude)

Hmmm.....let me now consult the literature regarding the optical colors of Type II-P supernovae.......(cogitation is now in progress!)

According to a study of type II-P supernovae by Kasen and Woosley (2009, ApJ, Vol.703, p.2205), the V-R color index of a type II-P supernova - in its plateau phase - is never more than 0.5, and often this color is only 0.3 to 0.4

In other words, if the Supernova is observed to be R magnitude 14.5, then the estimated V magnitude ("visual" magnitude) of this supernova will not be greater than 14.8 - 15
Or the V magnitude could be similar to the R magnitude (within the uncertainties).

Conclusion: if the observed R apparent magnitude of 14.5 is correct, then this "exploding critter" is quite bright, as its Visual magnitude may be only slightly fainter.
_____________________

Red Optical Colors of type II-P Supernovae:

One thing I did not realize before, because I am totally a "babe in the woods" when it comes to supernovae, is how red these type II-P supernovae actually are, in optical observations;
According to the aforementioned authors, the B-V color index of a type II-P supernova is often about 1 (or more) when the SN is in its initial (plateau) phase.
This should equate to a noticeable orange-red color in visual observations and photographs.
___________________________________ ___________

Because the observed Visual magnitudes of these type II events can be significantly brighter than the Blue magnitudes that I used in my estimates of how bright this SN is going to get (see a previous post in this thread), I will have to rework my "predicted brightness of this supernova" estimates.
_______________________

Best regards to all "SN crackers",
from the Mad Galaxy Man

I recommend Kasen and Woosley to all you SN enthusiasts, as it provides in depth analysis of type II-P light curves.

[RobF]

Congratulations Greg. So happy for you to finally have "one in the bag" after all the hard work by you and the rest of the team. Here's to many more! :thumbsup: :cheers:

[RobF]

Great shot Greg!
Be nice if the SN was marked in perhaps?

[Paddy]

Even more exciting! To save folk wading through my obs notes from the last couple of sessions, here are my notes on the supernova from last night. Thanks for the discovery and the heads-up - what a buzz! Hope to get a better night's viewing and make a sketch.


Supernova 2011gv in IC 4901 (GX in Pavo)

250X A viewing highlight indeed. Easy to find the galaxy as it is near a naked eye triangular asterism 1/3 of the way from Alpha Pavonis to the head of the peacock. To the preceding and slightly to the north of the faint galactic core is a tiny but distinct star. The galaxy itself is a faint glow slightly elongated roughly E-W 2 ½’ x1 ½’, the supernova visible within the western edge of the glow of the galaxy. There is a foreground star 3’ to the east of the galaxy. This observation before I’d even properly dark adapted. My plan to return later in the evening is foiled by cloud

[iceman]

Greg Bradley's image of the SN is a good one, and this story is so exciting and such a good news story, Greg's image is now IOTW (http://www.iceinspace.com.au).

I put the markets on the image and rotated it 180deg to match up with Greg Bock's image.

[gregbradley]

Marked in now. Iceman told me how it is done. I've never used the line tool before. Handy.

Image:

http://www.pbase.com/image/139036871

Greg

[pvelez]

Excellent work all round and well done Peter. What a buzz it must give you to find one of these suckers.

I was doing some asteroid photometry last night and took a 4 minute exposure through a V filter to see how it would show up. Its quite bright (though my image is v noisy). If the cloude keep away I'll take a few images over the next few day and see how its brightness tracks

Pete

[pvelez]

Oops - I mistyped. Congratulations to Greg for his find.

Pete

[Greg Bock]

FYI

Stuart has updated BOSS info here if you are interested.
http://parkdale-supernova-factory.webs.com/bossteam.htm

One of the pics of my observatory there shows just how small it really is...that's why I call it a 'micro-observatory'.


goodnight all, storm coming, must get some sleep!

[Ross G]

What an amazing story.

Congratulations Greg.


Ross.

[jjjnettie]

:D Congratulations Greg. All that hard work, and finally one of your own. Well done!!!

[deniseselmo]

Congratulations, Greg!!! Well done!:thumbsup:

[madbadgalaxyman]

Here is the light curve of a typical type II-P supernova, from the paper by Kasen and Woosley (as cited in a previous post)

102903

It is most remarkable how the visual (V-band), red (R-band), and near-infrared (I-band) light of a typical Type II-P Supernova stays constant for a long time. In contrast, the Blue (B-band) light falls off steadily, and the very-near-ultraviolet (U-band) light falls off rapidly.

The strong pulse of U-band (very near ultraviolet) light at the very beginning of the supernova event also looks extremely interesting.

These "exploding critters" do some strange things!