I want to draw attention to a supernova impostor that has flared back up, and some are saying it could have gone supernova. Here is a link to the relevant Astronomer's Telegram:
http://www.astronomerstelegram.org/?read=4412
Supernova imposters are visually as bright as supernova but they do not destroy the progenitor and some of them, like SN 2009ip have a repeat eruption. As the ATEL reports, Nathan Smith has guessed that this one might have popped off as a true supernova this time. Eta Carinae's great eruption in the 1840's is the prototype for this kind of object in our own galaxy.
Observing this object is a stretch for most northern hemisphere observers because it is at Declination -29. However it is an object of great interest and any good CCD photometry would be appreciated. Johnson V is normally most helpful. Cousins R and I are also useful for supernova impostors (because dust production can make them redder as they evolve).
Here is a link to photo on flicker with the object marked.
http://www.flickr.com/photos/watchingthesky/7791233138/
Note that the star to the immeadiate northeast of the target is pretty red. So depending on the airmass you are looking through and the filter you are using those two stars may be blended or appear as individual stars. It is my belief, based on data from Deep Sky Survey images that the nearby star to the northeast is faint enough in V and R that SN 2009ip overwhelms it completely in the photometric recudtions. The images that I took on September 11, 2012 show 2 distinct stars in the I-band but only a single star in the V and R bands. In my V and R band images the sky level was higher than the quoted brightness of the star to the immeadiate north-east.
I have made a VPHOT sequence for this that I am willing to share with anyone who wants to take some frames and reduce them in VPHOT. You can reach me here or jmart5_at_uis.edu
I should have added that SN 2009 ip was about 17 - 18 mag in V, R, & I at last measure about two weeks ago.
SN2009ip is rapidly dimming and reddening. It is probably not a true supernova. See ATEL 4416:
http://www.astronomerstelegram.org/?read=4416
To follow up on John's report, the object has started rebrightening at optical and UV wavelengths -- see ATel #4423 and #4425. It's a very odd event for sure.
Actually that data fits supernova impostors better. See (Kochanek et al., arXiv:1202.0281, http://arxiv.org/pdf/1202.0281.pdf). There will be more on ATEL today or tomorrow.
An update: SN2009ip in V-band dropped in brightness about 2 magnitudes in two weeks and then shot up three magnitudes in the last 40 hours. Thanks to Josch Hambsch for getting images last night that showed the V-band brightness now at 14.8 +/ 0.1. Just two days earlier it had been measured at 17.7.
What's next? Is it a core collapse supernova? Is it a supernova imposter? Its anyone's guess. Only the data will give us the answers so keep watching.
If I remember correctly, this level of fluctuation and time scale is typical behavior for an LBV. An example is the one we monitored in NGC 3432 (Wagner et al., 2004PASP..116..326W ).
Right now, I would consider it a fun object, bright enough to monitor with a 14-16" class telescope, but not a supernova.
Arne
During Eta Carinae's great eruption (1840-1860) it fluctuated widly between an absolute bolometric magnitude of -10 and -14. SN 2009ip could fit that desciption.
I cringe at calling it an LBV because it isn't clear if the underlying physics for the instability is the same for all objects refered to as LBVs.
But this is a really interesting object that should be accesible to most AAVSO members. A little brighter and the visual (nono-CCD) people could get involved. The colors are weird. So images in multiple filters are encouraged.
NIR Spectrum of SN 2009ip on 2012 Sep 27.3 Confirms Interpretation as a Type IIn
http://www.astronomerstelegram.org/?read=4431
http://arxiv.org/abs/1209.6320
Mauerhan et al.: The Unprecedented Third Outburst of SN 2009ip: A Luminous Blue Variable Becomes a Supernova
Some reports of supernova (SN) discoveries turn out not to be true core-collapse explosions. One such case was SN 2009ip, which was recognized to be a luminous blue variable (LBV) eruption. This source had a massive (50-80 Msun) hot progenitor star identified in pre-explosion data, it had documented evidence of pre-outburst variability, and it was subsequently discovered to have a 2nd outburst in 2010. This same source rebrightened again in 2012, and early spectra showed the same narrow-line profiles as before, suggesting another LBV-like eruption. We present new photometry and spectroscopy of SN 2009ip, indicating that its 3rd observed outburst in under 4 years appears to have transitioned into a genuine SN. The most striking discovery in these data is that unlike previous reports, the spectrum exhibited Balmer lines with very broad P-Cygni profiles characteristic of normal Type II supernovae (SNe II), in addition to narrow emission lines seen in SNe IIn and LBVs. Emission components have FWHM 8000 km/s, while the P-Cygni absorption component has blue wings extending to about -13,000 km/s. These features are typical of Type II SNe, but have never been seen in a nonterminal LBV-like eruption. Initially, the peak absolute magnitude of M_V \sim -14.5 seemed fainter than that of normal SNe and faded much more rapidly. However, the source quickly brightened again to M_R=-17.6 mag, indicating that it is indeed consistent with a true SN. In this bright phase, the broad lines mostly disappeared, and the spectrum became dominated by broad-winged Lorentzian profiles of H-alpha and HeI that are characteristic of the early optically thick phases of luminous SNe IIn. We conclude that the most recent 2012 outburst of SN 2009ip is most likely a true core-collapse SN IIn that was initially faint, but then rapidly achieved high luminosities, as a result of interaction with circumstellar material (abridged).
More info with light curve and spectra: http://arxiv.org/abs/1209.6320
Seems a little premature since the light curve hasn't even turned over yet.
I am doing a time series on this tonight in Rc that will go about 6 hours. Will see if there is anything interesting happening on short time scales and report back.
TG
I'll be interested to see what you get. I'd like to add that the color of the object has been a little odd so if you were to do it with a few V exposures as well, the (V-R) colors reveal additional information.
Let me know if you want or need a VPHOT sequence or my list of APASS stars in the field. I am happy to share the one I developed.
BTW if Arne is reading, I should pass along that in the course of doing the SN2009ip follow-up I've heard other professionals say they are extremely pleased with APASS and impressed with the accuracy and results it gives. I told them to thank Arne and the AAVSO.
Thanks, John! It is always gratifying to know that the hard work by myself and many others on APASS fills a community need. There are many improvements ahead to make it even better.
Arne
I second that on APASS. As an amateur very interested in supernovae, the APASS stars have proved to be most helpful in photometry.
Stan Howerton
http://www.flickr.com/photos/watchingthesky
Time series last night for 6 hours showed nothing eventful, except for a possible flare from JD 6200.1933 to 6200.2008 (just 11 mins) of 0.08 mag towards the end of the run.
I cannot rule out that this is spurious, although checking to see if the images at that time were trailed, or had some other problem didn't turn up anything unusual. I also checked if there was a relationship between image FWHM and delta mag (difference between the measured mag at an instant and the trend magnitude). Again negative. My experience of SN photometry has been that if the SN is within the glow of galaxy light, variations in measured mag may be correlated with image FWHM, as different amounts of galaxy light might be smeared into the photometry aperture. In this case there was no appreciable correlation - probably the SN is far enough away from the galaxy nucleus for this not to be a problem.
I cannot report an absolute mag because I don't have a sequence with Rc mags, and APASS doesn't have Rc.
I'll switch to V tonight so I can report Vmag. Short term events will only be credible, though if there is corroboration by another observer.
TG
Hi TG,
While APASS only observes at B,V,g,r,i, you can convert gri into Rc/Ic quite easily. The rough approximation can be obtained from the Sloan site: http://www.sdss.org/dr5/algorithms/sdssUBVRITransform.html
There, they state that, for all stars with (Rc-Ic) < 1.15, you can use the relations:
V-R = 1.09*(r-i) + 0.22 0.03
Rc-Ic = 1.00*(r-i) + 0.21 0.01
We use something similar to this in Seqplot, so that is the easy way to get the full BVRI:http://www.aavso.org/seqplot/
We have a more complete transformation between APASS gri and Cousins RcIc that will be published soon, but the approximations given above get you pretty close. For any sequence/comparison star that does NOT have a specific magnitude on the VSP chart, you should include what magnitude you used in the notes/comments field of your AAVSO submission.
Arne
See Arne's comment about doing Rc with APASS. Those conversions are accurate to 100ths of a magnitude. I have a sequence in V, R and I for the field that I can share with you through VPHOT or as a text table if you would like. Let me know.
The night to really have gotten that sequence would have been on Sept 25/26. It looks like it has leveled off for the most part now. But as I've said, its not clear what it will do next.
I agree with your comment about FWHM.
I am putting together a web page with a plot of the recent photometry. I'll post the link when I get it finished later today. Send along your magnitudes to me at jmart5_at_uis.edu if you would like to contribute to that.
John and Arne,
Thanks for the info about converting gri to VRc. To make sure we use the same reference point it would be great if John, you could send me the V R I sequence for the field. I am at tgtan_at_bigpond.net.au
I see there is no photometry data with the AAVSO on SN 2009ip. Is there another ID for this object which does have data? John, would you like the data in AAVSO format, or just JD, mag, err?
Last night's data in V is intriguing. A smooth level light curve, but with a 15 min flare of about 0.1 mag, similar to the flare I saw in Rc last night. There was a gradual increase in FWHM through the night, but nothing to explain this apparent flare. This is in a dataset where for the Vmag 11.8 stars in the field the scatter was only about 2 to 3 mmag. The object is currently at Vmag = 14.1.
The 1 hr gap in the data is embarrassing! I got the CCDCommander script wrong...
TG
Type IIn can be a catch-all for any object that brightens like a supernova and has narrow emission features (like the spectrum of Eta Car). The Zwicky Type V supernova have historically been swept into this catagory by spectral classification.
I wonder where the IAU bulletiun is if this is really concrete? I haven't seen one.
http://www.astronomerstelegram.org/?read=4439
They also used APASS r' and i' magnitudes for 5 comps stars, converted to R and I.
I have set up a web page for the photometry that AAVSO members have helped me collect:
https://edocs.uis.edu/jmart5/www/barber/SN2009ip.html
I want to especially thank F.-J. Hambsch with his Remote Observatory Atacama Desert and T.-G. Tan with the Perth Exoplanet Survey Telescope for their continuing contributions.
I'll keep updating that page as I continue to get new data.
Note that the V-I color on this object has been pretty blue.
Last night's (1st Oct) data shows the object has brightened to Rmag = 13.9 from 14.0 on 29th Sept.
TG
I've put together a light curve of CV and V photometry since the discovery of the 2012 outburst on July 24. http://www.flickr.com/photos/watchingthesky/8045530804
Data thus far come from my examination the FITS of CRTS SNHunt, various ATels, and through images taken with iTelescope.net. The photometry at which I arrived is a little fainter than quoted through CRTS in the ATels as different methods were used.
There seems to be a relatively smooth curve as the object brightened and then faded during the LBV phase. Not sure if that is real or just my trying to see a pattern in so few data points.
Stan Howerton
I was at a meeting at the begining of the week in Minnesota where Roberta Humphreys got up and reminded us all that normally an LBV refers to the S Dorodus type irregularity in the brighness/luminosity of a very massive star. Eruptions are not strickly speaking LBV activity and may be caused by a different mechanism entirely. Others chimed in that they feel stars in the LBV phase might be "stuck" somehow in their evolution and the outbursts might "unstick" them. So there may be a relationship but it remains to be clearly shown. Not all LBVs may erupt. So eruptions are may not be LBV activity.
So in keeping with what Roberta Humphreys proposed, I'd call this an "eruption." We don't know enough about the progentior to tell if it was or wasn't an LBV before this started.
After being essentially constant at 14.0 in B, V, and R for three nights, last night it was 13.9B, 13.8V, and 13.9R. Can anyone confirm this?
R image: http://www.flickr.com/photos/watchingthesky/8055061044
Stan Howerton
Stan, I am glad to see you interested in this. I remember photometry you did for Kris Davidson on Eta Car that was really helpful.
I've seen it getting just a little brighter each night.
https://edocs.uis.edu/jmart5/www/barber/SN2009ip.html
Last night Josch Hambsch's data showed V = 13.83 +/- 0.05 and I = 13.77 +/- 0.07 that was about Oct 4 @ 01:00 UT. It has continued to creep up a little each night but I've seen less than 0.1 mag over each 24 hour period for the last four days.
Maybe you've gotten something more recent by 12 hours or so but I haven't noted this yet. I'll keep a close eye on what Josch sends me for tonight.
Sorry to say that was not me.
Stan Howerton
Sorry if I mistook you for someone else. No excuse but the normal excuse of too much work and not enough sleep.
Last night (4th Oct), it was R = 13.7, compared to R=13.9 on 1st Oct. So still brightening.
High cadence photometry showed smooth light curve.
TG
[quote=HSW]
After being essentially constant at 14.0 in B, V, and R for three nights, last night it was 13.9B, 13.8V, and 13.9R. Can anyone confirm this?
R image: http://www.flickr.com/photos/watchingthesky/8055061044
Stan Howerton
[/quote]
[quote=TTG]
Last night (4th Oct), it was R = 13.7, compared to R=13.9 on 1st Oct. So still brightening.
High cadence photometry showed smooth light curve.
TG
[/quote]
I'll join on the end of this parade:
https://edocs.uis.edu/jmart5/www/barber/SN2009ip.html
I'm a bit conservative than most in that I look for three points to draw a line. But based on the last three nights of data, it looks like the slope in the V and I curves has increased upwards.
Note that through this the (V-I) color hasn't changed significantly. I'd like to see more observations in R-band. I know it is contaiminated by H-alpha but that is precisely why I'd like more observations. Isn't it a bit funny that the V, R, and I magnitudes are all roughly the same. I'd like to see a spectrum because if I was more sure on the R (i.e. had more observations to go on that followed the same trend with the few we have), I'd speculate that the H-alpha line has certainly not increased and has mayb decreased. Keep on watching it!
Had an unexpected break in the clouds so I set up the 17.5-inch Dobsonian. Estimated SN 2009ip at 13.5. Might have overestimated the brightness a tad.
Sequence used for comparison as well as more details of the observation: http://www.flickr.com/photos/watchingthesky/8037678412
Stan
I was able to take a spectra of this item last night. It shows quite strong hydrogen emissions but they are quite narrow.
see here
http://users.northnet.com.au/~bohlsen/Nova/sn2009ip.htm
Terry Bohlsen
[quote=TCB168]
I was able to take a spectra of this item last night. It shows quite strong hydrogen emissions but they are quite narrow.
see here
http://users.northnet.com.au/~bohlsen/Nova/sn2009ip.htm
[/quote]
WOW! Nice job. I haven't seen anyone go after a spectra of this with less than a 4 meter telescope. It has gotten bright but I am still impressed! You should go crow about this on the spectroscopy forum as well.
I would encourage you to make some measurements comparing your spectrum with those reported by Maurhan et al., ATEL 445 ( http://www.astronomerstelegram.org/?read=4454), and ATEL 4435 ( http://www.astronomerstelegram.org/?read=4435). Then write up a quick paper for the JAAVSO. I'm happy to critically read what you write and give feedback if you'd like to have that, but you should be the solo author on this. This is a real nice contribution that I'd like to see you get full credit for in the literature.
[quote=TCB168]
I was able to take a spectra of this item last night. It shows quite strong hydrogen emissions but they are quite narrow.
see here
http://users.northnet.com.au/~bohlsen/Nova/sn2009ip.htm
[/quote]
Actually I also jut had the thought that if you wanted to write an ATEL (Astronomer's Telegram) on your spectra, I'd be happy to sponsor you to do that with you as the solo author.
Hi Terry,
indeed to have a spectrum from such a dim target is an achievement.
Congratulations.
Josch
If this star is such a Big Deal, why are no magnitude estimates/measurements posted with the AAVSO except two by me (raw CCD-vis) in early October? Now I have a third showing a dimming to 14th mag. Clearly the star is a variable no matter what its type.
Since joining the AAVSO, I had not been able to find most supernova I was interested in the database. I'll admit that I gave up checking and didn't check this one. But now that I know it is there I'll be uploading my data... but a large amount of what I've collected belongs to other people so I'll have to deal with that differently.
Hi, John,
Since VSX wasn't meant to include extragalactic variables, a comprehensive listing of all supernovae was beyond its scope. However, bright supernovae have been observed by AAVSOers and in the new CCD era the number of supernova observers has grown exponentially. All SNe that have been observed or appeared in some alert notice, were assigned an AUID so people could submit data. In the past all these supernovae's light curves could be checked through the light curve generator but they were hidden to the public in VSX (due to their extragalactic nature).
In the recent months we have changed that policy to make it more inclusive so all targets of interest are visible in VSX. So every bright supernova that goes off or receives attention will be entered to VSX and observations could be submitted for it right away. Don't expect the run-of-the-mill 18th mag. supernova to be included though...
Best wishes,
Sebastian
-------------------------
Sebastian Otero
VSX Team
American Association of Variable Star Observers
I have certainly submitted SN measurements in the past. I remember also submitting the images via ftp. Is this still the case?
Also a BVRI sequence would be good for this extragalactic variable.
Cheers
Terry
Hi Terry,
If you need new sequence for any variable you are going to observe, you can find here how to Request Comparison Stars for Variable Star Charts.
[quote=FRF]
Hi Terry,
If you need new sequence for any variable you are going to observe, you can find here how to Request Comparison Stars for Variable Star Charts.
[/quote]
I have a sequence for CCD observers I am willing to share either through VPHOT or as an XLS file.
[quote=STI]
If this star is such a Big Deal, why are no magnitude estimates/measurements posted with the AAVSO except two by me (raw CCD-vis) in early October? Now I have a third showing a dimming to 14th mag. Clearly the star is a variable no matter what its type.
[/quote]
I have data on SN2009ip which I could submit to the AAVSO, but I'm not sure of the usefulness of such data. I have in the past submitted data on SN (SN2011iv, ja, SN2012aw) but these were 'experiments' looking for short term variations in SN light curves in consultation with Dr Brad Schaefer.
I will submit this data unless others think this is a waste of space!
TG
Dear All
I took a follow up spectra last night. It is essentially the same as the last one. No P Cygni features visible and narrow H lines.
The images and data are on the same page as before.
http://users.northnet.com.au/~bohlsen/Nova/sn2009ip.htm
Cheers
Terry
Everyone watching the astro-ph pre-print server has probably noticed a bunch of papers lately about SN 2009ip. I'd like to point out one in particular:
http://arxiv.org/abs/1210.3568
I think this one is particularly useful because it contains an impressive amount of data going back to 2009 when this object was first noted. It also advocates a wait-and-see approach about the question if this is the end of the road or not for SN 2009ip. The joke in professional astronomy (kind of a Murphy's Law of paper titles) is, if the title of your paper ends in a question mark then the answer is probably, "no." :)
Andrea Pastorello (http://arxiv.org/abs/1210.3568) has generously provided me with the photometric offsets between the comparisons his group has been using and the APASS comparioson photometry I have been using (and sharing with yall). The following corrections should be _added_ to photometry solutions done with APASS to directly compare with Pastorello et al.:
dV = +0.063 dR = +0.046 dI = +0.023
Please do NOT apply these corrections on photometry you are sending me. If you have that is okay, but I'd prefer not and please note clearly if you do. The purpose of these are for if you want to compare photometry you have measured using APASS standards with the work of Pastorello's group. In that case, apply those offsets before you make the comparison.
I wanted everyone to know that I'm at the AAVSO meeting this week. My talk Saturday is not about SN 2009ip but I'm happy to chat about our current favorite supernova (or not) with anyone that is here.
A day after an ATEL talking about SN2009ip's "quick" decline in the IR, Josch Hambsch sent me images that showed it got brighter. I chuckled but thought better of jumping on it right away. Last night, it again got brighter in both V and I. Ivan Curtis confirmed it in R-band. And not only is it getting brighter but it is getting bluer again.
I've stated my personal policy is that I prefer to use three points to draw a line, but I thought a quick note here for AAVSO people would be worthwhile.
I'm not even going to venture a guess as to what might be causing this but it is unusual. If it continues to brighten at a rate of about 0.1 mag/day (as it did for the pas two) that would put it back above 14 magnitude again at the end of this week.
My V data shows a brightening trend too. Wasn't certain until last night's image as the remote images for the previous two nights didn't take either due to weather or equipment problems. Clouds at my location have been a persistent problem.
http://www.flickr.com/photos/watchingthesky/8045530804
Very unusual object!
Stan Howerton
The past few days my light curve has shown more variability in V than that of UIS Henry Barber Research Observatory. Is something more going on in shorter time scales?
http://www.flickr.com/photos/watchingthesky/8045530804
https://edocs.uis.edu/jmart5/www/barber/SN2009ip.html
We haven't noted any verifiable short term activity before this point in time. Frankly the up and down in our data over the last few days probably isn't real. We've had larger errors in the solution because of how faint the target has gotten and higher sky brightness (the moon).