BOSS very bright Supernova alert

[PeterM]

Hi all, bit of an alert here.
Early days, but Stu Parker may have discovered BOSS' brightest Supernova todate. The suspect SN is at about mag 11.9 in the superb galaxy NGC5643 in Lupus. The galaxy is large and relatively close at 50 million light years. It already has the professionals excited. Being this bright and away from the nucleus in an outer spiral arm makes this an ideal target for smaller scopes. So might be worth visual and spectra follow up by IIspacers as we await a spectra from the pros. This would be BOSS 56th Supernova if spectra confirms.
Images soon.

Object Designation Date (UT) R.A. (2000.0) Decl. Mag. p Offset Locale
PSN J14323388-4413278 2013 02 13.621 * 14 32 33.88 -44 13 27.8 11.9 U 74W 180S N5643

[astroron]

Great news Peter, Look forward to getting a look at it if the weather clears.
Cheers:thumbsup:

[allan gould]

Well done Stu and Boss. Thanks for the heads up Peter, I will attempt to follow this one photographically
Allan

[Greg Bock]

yes, very interesting this one, its a long way from the galaxy nucleus, so we are waiting impatiently to find out if its a new SN, or perhaps even a closer galactic nova. Either way, its brightness will be suitable for many IIS members to see visually too.

[Terry B]

Well done guys. I saw the CBAT note but it didn't say who had discovered it.

[Andrew Pearce]

Hi All

If anyone is interested in visually observing this suspected supernova and making magnitude estimates, the variable star R Lupi is located about 1 deg south of NGC 5643. The AAVSO has a reasonable chart for R Lupi with comparison star mags in the 11-14th mag range. I suggest this chart is used until Mati Morel or the AAVSO issue a specific NGC 5643 chart.

Perth has a clear night tonight, so we have the opportunity of seeing a 50m rock pass within 30,000 kms and a very bright and distant supernova at almost the same time!

Regards
Andrew

[Park123]

Thanks All
Yes still waiting!!!!!!!No word yet. So this isn’t a sure thing but still an interesting object. Once again lack of sleep due to searching in fact I was up all night the previous night and group member Colin came to the rescue and was able to do the measurement’s while I got some long overdue sleep.
Here is an image for a finder chart.
2X300 sec
2X200 sec
Stacked in CCDstack no processing. I actually skipped by this one while blinking as I thought it was a camera hot pixel, lucky I went back a few mins later for a second look!!:eyepop::eyepop:

Stu

[DavidTrap]

Fingers crossed Stu.

Hopefully Terry can get some clear skies and aim his LISA at this ASAP.

DT

[malclocke]

Amazing work as usual guys, well done. It does look a long way from the core ...

Had a look in the TAROT archives but it doesn't look like this is one of their targets.

Looking at the DSS there isn't an obvious progenitor at those coordinates, see screenshot.

Will be watching this one with interest, thanks for the heads up.

[PeterM]

We just got word from the professionals at Gemini South that it is a type 1a supernova probably at or near maximum light. This is one of the brightest in a while and well worth amateur follow up. Almost any scope should be able to get this one.

[OzEclipse]

Congratulations Stu and the rest of the BOSS team. Love the work you guys do!

Joe

[Rob_K]

Congratulations!

Here's a roughie from tonight, taken from the carpark of the motel I'm at, streetlights, passing cars and all! The galaxy is barely visible but the PSN is.

Cheers -

[pvelez]

Way to go Team BOSS!

Well done. Will try and get the spectroscope onto this one

Pete

[Andrew Pearce]

Hi All

I visually observed the supernova this morning. Apologies, I made a mistake with my previous post. The variable star reasonably close by is RT Lup not R Lup. Anyway at Feb 15.797 UT I made it mag 11.4.

It was a busy night with two bright comets (C/2012 F6 at mag 5.6 and C/2011 L4 at mag 4.5), the flyby of 2012 DA14 (which was easily followed with a variety of telescopes) and a whole host of interesting variable stars. The universe is still a very active place at the moment.

Regards
Andrew

[Park123]

As Peter says it is a bright and beautiful type Ia event here is the spectra info and the BOSS webpage has been updated here::thumbsup::thumbsup:


http://bosssupernova.com/


Spectra:


http://www.astronomerstelegram.org/?read=4817


ATel #4817; J. T. Parrent (LCOGT/Dartmouth College), D. Sand (Texas Tech), S. Valenti, M. J. Graham, D. A. Howell (LCOGT/UCSB) (jparrent@lcogt.net)
on 15 Feb 2013; 21:14 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: J. T. Parrent (jparrent@lcogt.net)
Subjects: Optical, Supernovae

We report spectroscopic observations of PSN J14323388-4413278 (listed on the IAU Central Bureau's TOCP page) that was discovered by the Backyard Observatory Supernova Search (BOSS) team on Feb 13.62 UT. A spectrum (range 350-1000 nm) obtained robotically on Feb. 15.70 UT with the FLOYDS (FTS) spectrograph shows it to be a type-Ia supernova, a few days before maximum light. A second spectrum (range 350-950 nm) was also acquired with the Gemini Multi-Object Spectrograph (GMOS) on the 8-m Gemini South telescope on Feb 15.38 UT, confirming the classification. After correcting for the recession velocity of its host-galaxy, NGC 5643 (1199 km/s, NED), the minimum of the Si II 635.5-nm absorption feature is found to be blue-shifted by ~10,960 km/s. Comparisons to other spectra with "Superfit" (Howell et al. 2005, Ap.J. 634, 1190) show similar overlap with SN 1996X near maximum light. By Feb 15.38 UT, there is no conspicuous signature of C II 657.8-nm, however a small depression is seen on top of the Si II 635.5-nm emission component, at 634.7-nm, similar to that of SN 2011fe near maximum light (Pereira et al. 2013, pre-print, astro-ph/0008463).

[madbadgalaxyman]

BOSS succeeds once again!!

I heard from Mr Marples that you are going to be co-authors of a scientific paper. This means that each of you will get a record of citations (by other scientists in their papers), which is in fact the distinguishing mark of a professional scientist....

This is a very difficult thing to achieve (normally restricted to people with PhDs!), because to get professionally published means essentially that, at least jointly, you have mastered a very very large body of knowledge and have done a colossal amount of work. It is not at all easy to become a published astronomer!!

Here is the B-band (photometric blue filter) image of NGC 5643, from the de Vaucouleurs atlas of galaxies : :

132699

The dust pattern within this galaxy is asymmetric and unusual, which could hypothetically be due to an interaction with a low mass companion galaxy.

There does exist a low contrast, fairly long, central bar structure in this galaxy, but it is more obvious in near-infrared imagery. The large-scale dust lanes seen within this bar seem to be rather weak, and not very symmetric. (this galaxy is usually classified as "weakly barred")

Here are the isophotes of the bar, as seen in the Ks band (near-infrared) from Mulchaey et al., 1997, ApJS, Vol.110, p.299 : :

132700

(1997 was when NIR observations were in their infancy; there are better images around these days at NIR wavelengths!)

An extant Analysis of some 2MASS near-infrared imaging data for this galaxy derived a bar Position Angle of 85 degrees, and a bar Ellipticity of 0.67
The figure of 0.67 indicates that this bar is relatively "fat" (oval in appearance)

The immediate region near to the centre of this galaxy is very intense (high surface brightness), in the optical regime. It is not possible to actually see much of an active (Seyfert) nucleus in this Hubble Space Telescope (WFPC2 instrument) image of the centralmost region of this galaxy [Visual (V-band)image in the left panel, and H-band (infrared) image in the central panel ] : : :

132698

However, the "starlike" nucleus is catalogued as a Type 2 Seyfert , and I seem to recall that there were some observations of a short outflow of gas from this nucleus, which was detected in both the [OIII] line and X-rays.
(It might just be possible to detect the Seyfert nucleus in very short exposures, or visually)

[venus]

Great work!

[PeterM]

Thanks for that Robert,
There are infact a couple of papers in the works for the Astrophysical Journal with BOSS team members included in the authors list, but they do take time for acceptance, peer review I guess. The one listed below "Multi-Wavelength Observations of Supernova 2011ei: Time-Dependent
Classification of Type IIb and Ib Supernovae and Implications for their Progenitors", has been accepted for publication in The Astrophysical Journal.
Of course we are blown away by this, how incredible that professional astronomers would include amateurs in their list of contributors.
To all IISpacers reading this take note that any contributions you make to the science are highly regarded by the professionals and who knows where this can lead to.
The BOSS team are very proud to be able to let Ice In Space be the first to know of our discoveries and achievements in the hope that it inspires you knowing what amateurs can contribute to. Not only in Supernova discovery but a whole range of work from the incredible spectroscopy being done by several highly talented IIspacers here to Variable Star work, Occultations, Comet discovery, monitoring of Solar activity, monitoring Jupiter and Saturn, radio astronomy to our world beating imagers.
As I have often said BOSS are just like everyone else here we get our buzz from astronomy and we have found our niche.


http://adsabs.harvard.edu/abs/2012arXiv1207.2152M
http://arxiv.org/abs/1207.2152

[Terry B]

Dear Peter
I achieved a spectrum last night. It fits well with a Type 1a SN at maximum. See attached

Terry

[madbadgalaxyman]

Hello Pete,

Getting a preprint of a paper onto the Astronomical preprint websites of //arxiv.org and //adsabs.harvard.edu is essentially equivalent to actually being published, these days, because nearly every paper which is going to be formally published (after being peer reviewed) is put onto arxiv beforehand. Furthermore, it is a well known fact that there are usually few changes between the preprint and the actual published paper. The 100% legitimacy of preprints is tacitly acknowledged by professional astronomers, as shown by the fact that preprints are often cited in other papers.

Most professional astronomers want to get their hands on the newest scientific papers, as soon as possible, so as to advance their scientific efforts in the most speedy way;
therefore the first port of call for professional astronomers is very often to view the preprint of a paper at //arxiv.org or //adsabs.harvard.edu, instead of waiting for the publication of the actual periodical that contains the finished peer-reviewed paper! Obviously, professional astonomers wish to get hold of the newest work as soon as possible. Therefore, the impact of a preprint that is put on arxiv can be greater than the impact of the paper when it is finally published!!

Best Regards,
Robert, alias Mad Galaxy Man

[PeterM]

Terry that is fabulous work, congratulations indeed. As you know I have sent some of your spectra to our contacts at Las Campanas for comment, they have responded that they are very good and will comment further in detail but are very time poor at the moment.
Why not send this to Dave Bishop as I am sure he would be delighted to include on the Bright Supernova Page http://www.rochesterastronomy.org/snimages/

[mithrandir]

I took time out from trying to hunt out 2012 DA14 (failed) to see if I could find this PSN through Sydney's light pollution and high cloud. 9x60sec, 127ED, Sony a77. Pretty rubbish, but Unimap tells me I have an object at the right RA/Dec.

[avandonk]

Congratulations to all the BOSS team. Here is my tiny contribution with some images.

Spent last night taking data with NGC5643 at the centre of my field.

This is a stack of five luminance images of sixty seconds each 5MB

http://d1355990.i49.quadrahosting.com.au/2013_02/NGC5643_L_60s_.jpg

With a field of 3.5x3.5 degrees and about five exposures to eliminate cosmic rays this system can cover a big area of sky in a short time. I do not know how sucessful blinking would be with such a large area full of stars.


RGB 17x4 minutes for each full field 9MB

http://d1355990.i49.quadrahosting.com.au/2013_02/NGC5643_RGB.jpg


A full resolution crop with the SN at centre. 16 bit tiff 10MB

http://d1355990.i49.quadrahosting.com.au/2013_02/NGC5643_RGB_crop.tif


I dont know how useful my system is for SN searching. These images may give you a better idea Peter. I did take a range of luminance images from 30 seconds to 2 minutes. One minute looked to be optimum.

The last image below is a crop from the one minute luminance stack.

I forgot to say you are welcome to use any of these images.

Bert

[clive milne]

Well... all this scientific fluff and stuff is all well and good, but what we really need at this point in time is another image of M42.

[Terry B]

If there was a "like" button then this post would get one.:D

[malclocke]

I see we have a slightly more palatable name to use now, SN 2013aa :)

[Terry B]

Ive created a page with the spectra and an annotated image of the SN here
http://users.northnet.com.au/~bohlsen/Nova/sn_2013aa.htm

Cheers

Terry

[Park123]

Hi Terry,
Many thanks for this

this is fantastic work very well done you spectra looks REALLY GOOD.I really do wish that I was able to achieve this.I have passed your link on to a few of the astronomers that I know quite well for their comments I will pass on their thoughts.

Pretty dam cool:thumbsup::thumbsup:

Stu

[Park123]

Hi Bert
This look like very interesting images I have been thinking of using a hyperstar for similar searching to give a larger field of view could you please let me know what type of scope/camera you are using for such images.BTW the supernova is easily seen in you images. Well done

Stu

[Greg Bock]

All,
its great to see all the activity that this discovery has generated, well done to all, I that wish I could contribute, but its too hard under all the clouds here in SE Qld!!!

[avandonk]

This is my new system Stu

Astrograph is an Officina Stellare RH200 which has a focal length of 600mm and is F3, yes F3! Clear aperture is 200mm.
FLI Atlas Focuser.
FLI ten position filter wheel CFW-3-10 with 50mm square filters.
Astrodon E series LRGB and HA, NII, SII and OIII 3nm NB filters. Also a continuum filter 5nm.
Camera is a FLI PL16803 which has a sensor size 36.8 X 36.8 mm.
The FoV of this system is 3.5 X 3.5 degrees.
Mount is a Software Bisque PMX.


With the PMX mount it is a trivial exercise to take images of the exact same area over many nights while the object/s is/are visible. The goto has an error of seven seconds of arc rms!

I have yet to master how to script automatically a set of target areas for multiple exposures. There is a huge amount I still have to master that this new system is capable of.

I am willing to spend some of my clear nights on taking images of galaxy clusters or areas the Boss team is not covering.

Maybe I could start off with one or two targets and see how it goes.

I realize the dedication needed to consistently monitor for SN's is not trivial. We imagers are a masochistic lot already, are we not?

Bert

[cybereye]

Congratulations Stu and the BOSS team!! :thumbsup:

Cheers,
Mario

[Andrew Pearce]

Hi All

Mati Morel has generated a good chart for the SN now which is available through the AAVSO web site. I'd be wary of the mag 11.7 comparison star shown on the chart, it doesn't look quite right but the others appear fine. I visually observed the supernova again this morning and at Feb 17.756 UT it was mag 11.7.

Regards
Andrew Pearce

[Steffen]

Are you telling budding astro-imagers to bugger off and post their M42 pics someplace else, not IIS? :confused2:

Cheers
Steffen.

[Capricorn1(Tom)]

Congratulations Guys well done....it dosen't get better than that....Super Cool.:thumbsup: Cheers Tom

[Greg Bock]

And here's the Universetoday story, for anyone interested.

http://www.universetoday.com/100101/bright-new-supernova-shines-in-southern-skies/

[Weltevreden SA]

SN 2013aa seems quite remote into the halo of 5643, 2x beyond the last
visible traces of spiral arms and roughly 4x the virial radius. Even
though the spectral data recorded thus far and dist modulus indicate the
SN is part of the galaxy, it's the first time I recall a 1a occurring so
seemingly remote from its host galaxy. 5643 was included on several
watch lists of Sey2 galaxies for possible SN activity starting in 1997.
Proposals for HST time go back to 1995, so it's been an object of
curiosity for quite awhile. It's a dusty SBc with an an elongated and obscured core that doesn't fully meet Sey2 criteria (hence its designation "Sey2-like"). Now this, a 1a that to my understanding has
occurred far out in the galactic boonies where there's very low gas and
dust density, not much in the way of magnetohydodynamic turbulence, and no visible bar torque or recent interactivity with another high-mass object. Could 2013aa be in a faint dwarf orbiting 5643?

[madbadgalaxyman]

A very interesting comment, and it is very good to hear from someone in South Africa; a large proportion of our IIS members seem to come from Australia, and we don't get too many posts from SA. This is odd, as we share exactly the same sky!!

There has been a lot of talk in the recent literature about XUV ("extended ultraviolet") disks in spiral galaxies, as can be detected using the Far-Ultraviolet imaging band of the GALEX satellite;
It has been proven, from Galex FUV detections of star-forming knots found in the very outermost regions of spiral galaxies (the FUV bandpass is inordinately sensitive to current star formation), that star formation can occur a long way outside of the optically-bright disk of a spiral galaxy.

A good nearby example of this phenomenon is M81, in which the low-density intergalactic medium has nonetheless somehow managed to form knots of OB stars!!

As the wavelength-range and sensitivity of astronomical observations have progressively increased, there has been a tendency for astronomers to find ever more inter-galactic gas between the galaxies and ever more gas outside of the bright optically-evident bodies of galaxies. So astronomers now know of several sources of gas that can provide the raw materials for forming stars in the outermost parts of galaxies.

For instance:

- it has turned out to be the case that many elliptical galaxies are NOT gas-poor, as was the common so-called “knowledge”(actually a prejudice!) found in the textbooks about galaxies. There is often a massive interstellar medium of very hot X-ray emitting gas that surrounds an elliptical galaxy, and this gas could potentially cool enough to form new stars. There is also a colossal reservoir of very hot gas associated with many clusters of galaxies, often with more mass existing in the form of hot gas than is found in all of the stars of all of the galaxies.

- low column-density HI (neutral atomic Hydrogen gas) has been found in the outermost regions of many galaxies, and the total amount of this gas can be comparable to the amount of gas actually found within the prominent central regions of a galaxy. This gas was undetectable until very recently, due to its low density!

- Further evidence for the existence of large reservoirs of cold (and therefore, potentially star forming) gas existing outside of the obviously visible disk components of spiral galaxies can be found from considering the star-formation history of our own Galaxy; the Milky Way Galaxy has been forming stars steadily for all of its history, and the ongoing star-formation would have exhausted its total gas supply several times during its history, were there not some mechanism by which cold gas falls into the disk from above it and below it. The interstellar gas in spiral galaxies seems to be recharged by gas which is falling in from the halo of the spiral galaxy, or even perhaps falling in from intergalactic space.

- the intergalactic gas surrounding a galaxy, or the Low column-density gas that is actually associated with the outermost regions of a galaxy, can be caused to form new stars by the energetic effects of plasma beams originating in a central Active Galactic Nucleus, or by the energy of powerful shock waves that exit the disk of a spiral galaxy due to the effects of multiple supernovae.
For instance, in NGC 5128, the plasma beam from the central AGN has set off some modest star-formation in the outermost regions of this galaxy.

- Supershells (powerful shock waves, in a gaseous medium, coming from multiple supernovae) can expand outwards, reaching outwards to points which are a long way from the obvious bright disk component of a spiral galaxy, thereby providing adequate energy for the inception of star formation in clouds of cold gas existing in the outermost regions of galaxies.

One further point is that a galaxy does not have to look the same now as it did three billion years ago;

- there is evidence that a massive interstellar medium can be stripped from the outer parts of a disk galaxy by encounters with other galaxies or by the effects of "ram pressure stripping" of a galaxy's Interstellar Medium caused by high-velocity passages of the galaxy through a low density intergalactic medium. Thus, outermost stars and other outer features that are observed in a galaxy could be a residual of previous structures that no longer exist.

- Another process is also likely to exist, which affects a galaxy in the opposite way to the aforementioned exhaustion or stripping of gas from the outer regions of some galaxies;
the outer disks of spiral galaxies, and even the outer disks of elliptical galaxies(!!!) , can be gradually built up from the infall of gas!!
This seems to be happening in the S0/E galaxy NGC 1316, as was strongly indicated in a recent paper by Prof. Kenneth C. Freeman (of ANU) and colleagues.

Best regards,
madbadgalaxyman


Madbadgalaxyman's comment of the day;

"Yes, Virginia, elliptical galaxies do have disk components. Disks in elliptical galaxies just happen to be very faint, or very small in radius."

[Greg Bock]

Yes, good to hear from SA for a change, thanks Dana.
Your comment about a dwarf interests me because i was wondering the same thing a few days ago. So, here's a challenge.
Can anyone, with clearer skies than us in SE Queensland, conduct a verrry long exposure campaign at the galaxy to see if there are any traces of a dwarf there?....just thinking out loud...:):).

[madbadgalaxyman]

Agreed, Greg, there could well be a dwarf galaxy there, which was the host galaxy of the supernova......
but, as I mentioned in my last post, there are several other ways for gas and star-formation (and supernovae!!) to occur in the distant outermost parts of a galaxy.

See, for instance, this intriguing study of the galaxy NGC 3108, which shows that a disk of gas and dust and newly-formed stars is gradually coalescing in its outer regions! An analogous process of "the extension of the stellar disk of a spiral galaxy to progressively greater radii" is believed to occur in some spiral galaxies.

http://arxiv.org/abs/0711.3232

Further to your interesting proposal, it is quite possible that super-deep amateur imaging would reveal Extremely Faint optically-luminous outer (stellar) disks in many spiral galaxies and even in many elliptical galaxies!

Best Regards,
Robert

[mithrandir]

I looked in Aladin and there is a star like object at 14:32:43.20 -44:10:12.0 in the IRAS-IRIS images. Rendered as R=100MU, G=60MU, B=25MU

[madbadgalaxyman]

Dana,

Further to your comments about the unexpectedly large galactocentric distance of the supernova in N5643.....

Here are two GALEX ultraviolet images showing star forming knots in the outermost regions of two galaxies. All of these far-ultraviolet-emitting knots are likely to contain OB stars that are the progenitors of core-collapse supernovae.

M83 . The distribution of knots looks like it could be connected with a gravitational interaction with another galaxy:

133221

NGC 404 . An S0 galaxy with little or no star formation evident in the optical regime, but in the far ultraviolet, it plainly has plenty of knots of OB stars in a disk-like structure:

133222

(the left panel is an optical image, and the right panel is FUV+NUV from the GALEX orbiting telescope)

cheers,
Robert

[Greg Bock]

So, using the GALEX M83 image as an example, it would be interesting to overlay a UV image of NGC5643 with an optical image at the same scale that shows the location of the SN. Would any OB star knots coincide. I wonder?

[Big Dave]

Its amazing how people spot these up, well done. My image was taken during a strong wind but it is visible. Compared it to the Sky X sky survey and it is new.

Thanks to the team for sharing.

[PeterM]

Now at mag 11.5, an, as best as I can tell from going through the bright supernova pages, it would appear 2013aa is in fact the brightest supernova discovery in the 26 years since 1987A! The next closest is 1980K in NGC6946 at mag 11.4
So well worth the effort to track this down visually for all those wanting to see the end of one stellar life cycle that likely starts another.

[DavidTrap]

Now that's cool!

DT

[madbadgalaxyman]

Peter,

this might be a very luminous supernova, as the total B-band (blue) apparent magnitude of the entire host galaxy is around 10.8 and the total V-band (visual) apparent magnitude of the entire galaxy is close to 10.0
(but I wouldn't bet that these magnitude figures are very accurate)

The HyperLeda Extragalactic Database gives a "guesstimate" (based only on the velocity distance of this galaxy and an estimate of the foreground extinction) of the luminosity of this galaxy as being Blue (B-band) absolute magnitude of -21.0
so maybe this supernova is notably luminous!!

What wavelength-band is the estimate of magnitude 11.5?

The all-important required "numbers" on extinction from foreground dust and the distance of this galaxy, are likely to be a bit "rubbery" at first, but perhaps we can come up with a reasonable estimate of the luminosity of this supernova

The galaxy itself is interesting, with some rather strong asymmetry. The arm structure and dust distribution on one side of this galaxy looks particularly unusual at shorter wavelengths, e.g. in this Carnegie Atlas image (blue)

133256


The underlying fairly-strong bar structure is fairly well shown in this near-infrared (J+H+K) image from the 2MASS:

133257

[Weltevreden SA]

Here is a good refresher paper on starform histories SB types in general, incl. 5643 in passing:

arXiv:astro-ph/0606460v2 (http://arxiv.org/abs/astro-ph/0606460v2)

Galaxyman's links to all the GALEX stuff is a siren song for someone chafing at lustrous skies arriving just in time for the full moon. I'd say the GALEX images will keep me off the streets for awhile, but my area is so remote there are no streets to be off of.

=Dana in SA

[Greg Bock]

And further to this, I see on the Bright Supernova Page that Stu has discovered the 2 brightest SNe for 2013..ie The brightest SN of the year are 2013aa (Mag 11.6) followed by 2013E (Mag 14.0) in IC2532...he's on fire alright!

[astroron]

Just to show how easy it is to observe;)

I observed SN 2013aa last night in the very bright galaxy NGC 5643.
It is quite far from the galaxy but as it is quite isolated from other stars is quite easily seen.
I used eyepieces from a University Optics 55mm magx 60,also 17mm Nagler 103xmag and 9mm Nagler 200xmag.
Scope used 16" truss Newtonian.
As stated elsewhere this Supernova will be easily seen in scopes from about 6" and above.
Copy the BOSS image from the thread on the discovery started by Peter Marples Here (http://www.iceinspace.com.au/forum/showthread.php?t=103349).
If you have not managed to observe a Supernova before, now is your chance.
Cheers:thumbsup:
__________________

[malclocke]

Managed to bag this visually tonight. Fairly low in the sky, and the moon was almost bright enough to read the finder chart by, but definitely visible in my 10" dob.

I used the AAVSO finder chart, and got magnitude 11.8 from the comparison stars. The second SN I've seen after SN 2012fr.

[madbadgalaxyman]

Can I assume that this supernova peaked at V (visual) apparent magnitude 11.5 ?

I seem to recall that the AAVSO variable star comparison atlas used V magnitudes for comparison stars around a variable (though I have not used these charts for years!) so I suppose that some approximation of visual magnitude, and/or the Johnson V photometric band, is a sort of de facto standard for magnitude estimation.

Another thing I clearly remember from my "very long ago" 12 months stretch of time when I was doing visual magnitude estimation (every clear night) using just the naked eye or binos together with charts, is how inaccurate some of the other observers' magnitude estimates were when compared to photometric measurements. A small number of visual observers consistently achieved an excellent accuracy of 0.2 (or even 0.1) magnitude, while a lot of others achieved an accuracy that was 3-5 times worse than this!!

My impression is that an accuracy of +/- 0.2 magnitudes is good going for visual estimates of the apparent magnitude of a stellar source, though perhaps some variable star observers can shed some more light on this.

cheers, Robert

[PeterM]

Hi Robert,
Sorry for late reply.
The 11.5 comes from the site below so I assume visual. Other estimates are listed below that so definitely peaked well below mag 12.
Keep your information and thoughts coming, as usual very interesting and informative.
Thanks!

http://ooruri.kusastro.kyoto-u.ac.jp/mailarchive/vsnet-recent-sn/4208
http://www.rochesterastronomy.org/snimages/

[Andrew Pearce]

Hi Robert

Being a visual variable star observer, I'd say your view on accuracy of +/- 0.2 mag is not far from the mark. It does depend on a lot of things. A key one is the accuracy and short gap in brightness between adjacent comparison stars. If you have a good sequence with say 0.5 mag or so intervals between comparion stars, then it's much easier to make an estimate and its generally more accurate. Also red colour long period variables can be difficult and can result in the loss of some accuracy. Also I find it much better if you are using an instrument size that doesn't show the variable star too bright or faint helps (ie estimating a 6th mag variable star in say a 16" scope can be difficult and lead to inaccuracies.

Hope this helps. By the way I visually observed SN 2013aa this morning and at Feb 23.871UT it was mag 11.3.

Regards
Andrew

[madbadgalaxyman]

"Just for fun and profit", here is a hydrogen-alpha image of NGC 5643 from Ryder's and Dopita's pioneering hydrogen-alpha imaging survey of southern galaxies
(1993, ApJS, Vol. 88, page 415)

133317

This data was reproduced at a logarithmic scale. It appears that they have already subtracted the Red Continuum from the raw H-alpha image, so this image shows H-alpha light only and excludes red starlight.

Here is the same data, but displayed at a linear scale:

133318

The H-alpha spiral structure appears not to be particularly strong and well defined. Given that this is not at all a dwarf galaxy, the relative disorganization of its spiral structure may be telling us something about the current events occurring in this galaxy at the time the light from it started its journey to our telescopes.

[PeterM]

Ok, I got the facts better now (thanks to David Bishop, Bright Supernova Page) so a bit of an amendment to my previous stating 2013aa was the second brightest Supernova since 1987A.
Below are the maximum brightness that all the brighter ones since 1987A reached.
2013aa appears however to be the 2nd brightest at discovery and as an AAVSO member has now measured at 11.3 even allowing a give or take for all of them 2013aa still ranks in the top 5 in the last 26 years (1987A -today infact 26 years ago - thanks Astroron for reminding me) and within a whisker of being the 2nd. Still a remarkable find, congrats Stu!
So to all you visual observers, have you seen it yet or are Astroron and Malclocke on their lonesome?

2013aa in NGC5643 max brightness around 11.3 this time
2011fe in M101 max brightness around 9.9
2011dh in M51 max brightness around 11.1
2004dj in NGC2403 max brightness around 11.2
1998bu in M96 max brightness around 11.6
1993J in M81 max brightness around 11.3

[malclocke]

For what it's worth, and to be taken with a suitable sized pinch of salt, my back of the envelope estimate for the galaxy core to SN distance is around 16kpc. This is based on an angular separation of 196 arcseconds, z=0.003943 for the galaxy and H_0=0.71.

[malclocke]

Hi Andrew,

I'm a complete newbie to estimating variables, and I'm way off with 11.8 compared to your 11.3 for around the same time. Were you using the AAVSO chart? If so, which comp stars did you use?

Thanks,

Malc

[Weltevreden SA]

Malc's z=0.003943 value for N5643, coupled with Robert's Carnegie blue and now his Ha images showing irregular disk torques got me to thinking about ancient interactivity affecting the gx. There's a faint galaxy, PGC 538542, roughly 6' SSE with a NED listed z=0.003595 (http://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=PGC+538542&extend=no&hconst=73&omegam=0.27&omegav=0.73&corr_z=1&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=RA+or+Longitude&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES) (subject to important NED "See essential note" caveat) and Heliocentr.radial vel. of 1078 m/sec. No transverse velocity available, but a back-of-envelope (and part of front) calculation makes me wonder if the PGC may have grazed 5643's arm some 55+ myr ago. The locale of SN 2013aa 196 arcsec fm 5643's core (thanks again, Malc) still has me wondering how it got there. Now the thought comes it might be an ejected binary system.

I wonder if any of IIS's experienced AP hands might try some very deep field images in the B band seeking faint emissions not recorded in existing images. Then, as per Greg Bock's excl suggestion, overlay the images on the SN and see what turns up.

[Park123]

Yes David Bishop’s web page is one of the most fantastic supernova sites on the net I went through his site yesterday to got the above information I was so surprised that it ranked so highly.
BTW-got a great image of 2013aa the other day with good seeing and some RGB will post later still nice and bright around 11.3 as Pete says.
What a BOSS find thanks all for really interesting posts keep them coming. If only we could find the
Progenitor wouldn’t that be cool.

Stu:eyepop:

[Greg Bock]

Stu, et al, weather here in SE qld will be rubbish until hell freezes over i think. Maybe someone with clear skies can do a long exp. image, Stu, you're probably best placed to do this!

[Park123]

Greg-Trying to get data but the moon bet me for the next week or so.
Might try some HA but I broke my HA filter need another one.
Just PLEASE send some rain over here we are as dry as a crisp:sadeyes:

WE NEED RAIN

Stu

[madbadgalaxyman]

Hello, Dana,
and Greg and Malc, and others who have commented about the large separation of the supernova from the host galaxy.

In practical terms, galaxies, when imaged to very very faint isophotes, are normally much larger in diameter than the diameter that is usually seen in amateur images, and galaxies are typically much larger in diameter even than the standard D25 diameter (to 25th Blue magnitude per square arcsecond) which is given for each galaxy in the galaxy catalogues.

(( The exact outermost Radial profile of surface brightness, as a galaxy's surface-brightness decreases with progressively increasing galactocentric radius, can have several different and well-defined forms. Some galaxies have a fairly sharp cutoff in light at some diameter, while other galaxies keep on extending outwards into the field .... even beyond 28th Blue Magnitude per square arsecond)

The best source of (southern) galaxy diameters to very faint isophotes is the “Surface Photometry Catalogue of The ESO-Uppsala Galaxies”(1989) by Lauberts and Valentijn , which is also known as the ESOLV (or the ESO-LV).
This very important catalog of bright galaxies is available in electronic form, and also (perhaps!) still in a paper version from the ESO.
Like the RC3, the ESO-LV is a large and homogeneous dataset, with relatively consistent and relatively high accuracy. The ESOLV is as important for southern galaxies as the Third Reference Catalogue of Bright Galaxies (=RC3) is for the all-sky bright galaxy population.

The ESO-LV gives the following angular diameters for the Major Axis (long axis) of NGC 5643:

Standard Diameter to 25th Blue magn. per sq. arcsec : :
305 seconds of arc (= 5.08 minutes)

Diameter to 26th Blue magn. per sq. arcsec : :
380 seconds of arc (6.33 minutes of arc)

Unfortunately, the ESO-LV doesn't give a diameter for this galaxy to the even fainter level of 27th Blue magnitude per square arcsecond, but the conclusion seems quite firm that a supernova which is 196 arcseconds (3.26 arcminutes) from the centre of NGC 5643 is still plausibly within the confines of this galaxy.

Now I would be as excited as the next man (or woman) if the supernova turns out to be associated with a dwarf companion of NGC 5643, but this numerical argument puts the conservative view that the supernova does belong to the big galaxy.

Here is the DSS image taken from wikisky.org, which shows the host galaxy extending outwards a lot further than it does in the other images in this thread;

133398

(this is far from being the sharpest version of Digitized Sky Surveys, but it shows the galaxies at higher contrast than the other versions!)

Best Regards,
from
Bad Galaxy Man

P.S.
How accurate are ESOLV diameters of galaxies? They are usually about right, but occasionally they are very wrong!!
If anything, the galaxy diameters in the RC3 are even worse, as they are simply derived from an extrapolation of the inner (radial) light profile. At least ESOLV galaxy diameters are actual measurements, rather than extrapolations, or averages of several bad data-points. Still, even ESOLV is better for statistical (large number of galaxies) work than for finding a really accurate measurement.

The only way to get a really accurate angular diameter is to do CCD surface photometry of a galaxy.

[mithrandir]

That catalog is available at Vizier as VII/115. eg http://cdsarc.u-strasbg.fr/viz-bin/Cat?VII/115.

It probably would not be too hard to load into CdC.

[astroron]

Looking at the image above and comparing it with the discovery image, is there a possibility that the progenitor is in that pic :question::question:
There is a triangle of stars in the position of the Supernova .
Cheers:thumbsup:

[Andrew Pearce]

Hi Malc

The AAVSO updated the original chart a few days ago and some of the comparision stars around 11th magnitude were the ones that changed. If you downloaded the chart a while ago, it may pay to download it again. There is a 11.1, 11.4 and 11.6 mag comparision stars on the latest chart which is what I have been using.

Regards
Andrew

[Weltevreden SA]

A bit tangential to this discussion proper but interesting in its own right, I count 18 faint galaxy-like smudges in a 7' circle around TYC 7818-2402-1 roughly 7.5' SSE (14h 32m 17.5s / -44° 19' 48.7") from 5643's core. Even discounting 20% for FEAR (false expectations appearing real) methinks there might be a small cluster out there.

Does anyone know the deepest isophote level of the Wikisky images?

Back to 2013aa and N5643, any thoughts on the ejectee hypothesis based on the z value and radial vel. of nearby PGC 538542? This gx looks to be in the vm 21-22 range but doesn't turn up on Vizier, though it does on NED.

[madbadgalaxyman]

Dana,
I do agree with you, that the small galaxy that you mention is likely to be part of the same bound Galaxy Group as NGC 5643. It is much less likely that this is a galaxy at a different distance which has a "peculiar" (non-cosmological) velocity.

[[ As we all know well, actual observed galaxy recession velocities, are in practice not actually proportional to galaxy distances, and a galaxy distance which is derived from a recession velocity could be greatly in error because of a large non-cosmological "individual" velocity of the galaxy. ]]

In general, outside of galaxy clusters, the local Hubble Flow within 2000 km/s seems to be very quiet. (the velocity-distance graph has few galaxies which are outliers). Aside from the Virgo and Fornax Clusters and the highly obscured Puppis Cluster of Galaxies, there are no large gravitational potentials within 2000km/s to move galaxies around with significant non-cosmological velocities.

Within 2000km/s redshift, I have found from long experience that (as we would expect!) the recession velocity of a galaxy is a good guide to (though not a measurement of!) a galaxy's actual physical distance, but there have been a very small number of individual cases where the velocity distance of a galaxy is very different from the actual as measured physical distance of that galaxy (obviously, because of the large individual velocity of the galaxy.)

My preferred tool for the initial investigation of the environment of a galaxy (galaxy clustering , and galaxy redshifts) and of adjoining regions of sky that are near to a galaxy, is the software starchart called "Guide 9.0" from www.projectpluto.com (http://www.projectpluto.com) :

- it is quick (you can move from field to field, and zoom, very quickly)

- you can click on galaxy after galaxy to bring up redshifts (and other quantitative data) quickly

- it is data rich; it displays >100,000 galaxies, and the "popup" information for each galaxy is very extensive.

- it is highly configurable - virtually any Galaxy Catalog or Deep Sky Object catalog can be quickly loaded into "Guide" so that all the objects in the catalog are displayed on the electronic star chart
(for instance, my "Guide" software is configured to display all of the objects in: several catalogs of AGNs, the Virgo Cluster Catalog, and two different catalogs of the Fornax Cluster galaxies!)

- very high positional accuracy

- the Deep Sky Object and Galaxy data is loaded straight from the object catalogs; I have therefore found that the quantitative data about galaxies is reliable

- "Guide" is a lot faster and more convenient than DSS or Wikisky if the goal is quick movement from galaxy to galaxy, and a quick appraisal of each galaxy and its environment

cheers,
Robert

[madbadgalaxyman]

Over 70 magnitude estimates for Supernova 2013aa in NGC 5643 can be found at the AAVSO website using the WebObs tool

Just go to :http://www.aavso.org/webobs

Then click on "search for observations"

Then put "SN 2013aa" in the search box, to find the observations.

Hello there, Andrew (Pearce),

I am currently fixated on trying to derive an estimated peak luminosity for the supernova; using its distance, its apparent magnitude, plus an estimate of the foreground extinction from our own Milky Way's dust screen. Currently doing a literature search to see if I can find something better than a distance derived from the galaxy's recession velocity! (because velocity distances can easily have errors of 20 percent, for galaxies which are at a recession velocity of ~1000 km/s)

Would you, or your fellow "variable star fanatics", like to have a go at deriving a reliable peak magnitude for the supernova, from the multitude of existing observations of this SN? [I am not familiar with the real (as against the "in my own mind") error budgets of the various observers]

I myself will have a try at getting some sense out of these 70 magnitude estimates, some of which are obviously very inaccurate.
Some of the errors given are absolutely ridiculous e.g. +/- 0.005 magnitude, which would be good going for the Hubble Space Telescope!

Also, looking at the large divergence between the various visual estimates of the supernova magnitude, I think my comment about some observers being easily half a magnitude out, are correct!! No sense in trying to make an average, or even a weighted average, of bad data points!!

cheers,
Robert

[Andrew Pearce]

Hi Robert

Welcome to the world of variable star observing! As you can see it can be quite a difficult thing to sort through observations and make sense of them in trying to determine the "signal" and the "noise" component. There is a very good book by Grant Foster, "Analyzing Light Curves - A Practical Guide" which gives various statistical methods that are commonly used by the AAVSO when analysing light curves which contain various degrees of scatter. I think it's fair to say that the CCD observations of SN 2013aa by only a handful of observers show less scatter than the visual observers and looking at the light curve, they seem to show a clear peak magnitude of 11.6 around Feb 20-22.

However from a visual perspective, the SN has definitely appeared slightly brighter than 11.6 and this can be relatively easy to judge as there is a nearby comparison star of 11.6 and I personnally have seen the SN brighter than this star. My own obervations indicate a peak brightness of 11.3. But as you can see from the light curve there have been visual estimates up to 11.0. I can't explain exactly why there has been a difference between the CCD V and visual observations.

A scatter of 0.5 mag amongst a bunch of visual observers is not uncommon. Also I'm not sure how much of an effect the fact that the AAVSO changed some of the comparision star magnitudes on the chart a short while ago has had and whether all of the visual observers were using these corrected magnitudes as this could affect the observations up to 0.2 mag or so.

Sorry for not really giving a definitive answer, but I feel the peak was somewhere between 11.3-11.6.

Regards
Andrew

[Rob_K]

This might be timely and interesting in relation to the discussion of galactic halos:
http://hubblesite.org/newscenter/archive/releases/2013/07/full/
http://hubblesite.org/newscenter/archive/releases/2013/07/image/a/format/web_print/

Cheers -

[Greg Bock]

Really interesting stuff Rob, thx for the links

[madbadgalaxyman]

Andrew,
Pity that I don't have the statistical tools you mention, in my 'mental toolkit', so as to sort out that messy magn. data.

But I do know (from experience) a lot about the errors made in visual observations, by means of the "wishful" thinking of the eye-brain system. Given that a 10 or 20 percent difference in apparent brightness is hard for the eye to spot, an observer's attitude (bias)(his preconceptions about object brightness) could well influence whether or not a star seems brighter, or the same brightness, or fainter, than a comparison star;
I think, at the level of 0.1 to 0.3 magnitude, a perceptual bias could easily creep in and distort the observer's visual magnitude estimate for a variable star.

Unfortunately, an error of 0.3 magnitudes in the apparent magnitude of the Supernova is large, when we wish to use it for the purposes of estimating the luminosity (absolute magnitude)(absolute brightness) of this astronomical object. The distance error for an individual galaxy can easily amount to 20 percent , which equates to an additional error of 0.4 magnitudes in the derived luminosity of the supernova.

Galaxyman's question to Mr "Variable" Pearce:
Do your visual (that is, made using the "eye+brain system") magnitude estimates need to be mathematically transformed into the Johnson V-band Magnitudes for the purpose of making a really accurate comparison with V-band measurements made using photoelectric and CCD photometry??

Some of my textbooks state the following:
(1) The Johnson photometric V-band filter was actually chosen so as to approximate the visual response (the band-pass) of the eye (the eye's response curve). That is, the filter's transmission curve has a peak filter transmission (maximum brightness) near 550nm and a Transmission Curve width ( Full-Width-at-Half-Maximum) of about 90nm.
(2) The bandpass and sensitivity curve of the eye is, however, different from that of the standard photometric V filter, being composed of a complex mix of responses from the rods and from three different types of cones.
(e.g. the well-known shift of about 50nm in the peak sensitivity between the rods and the cones)

Therefore, do visually-estimated magnitudes (visual magnitudes) need to be mathematically transformed into V-band Johnson-Cousins magnitudes, if they are to be accurately compared with V-band magnitudes?

cheers,
madbadgalaxyman

[Suzy]

Congratulations Stu and to the rest of the BOSS team- what an extra fantastic discovery re it being such a bright one.
I'm so excited that I finally get to observe one from you guys!
Sorry about the late response, I've been posting this news all over the place on facebook but I forgot to come back here to the source (I'm normally pretty quick to applaud you guys) ... so embarrassed! :ashamed:
It seems to be raining forever here in South east Queensland grrrr :mad2:.

[madbadgalaxyman]

Hello all,

As mentioned in a previous post, the perception that this supernova is "a long way out from NGC 5643" is essentially a perception created by the limited sensitivity of our observations.

For instance, the surface photometry of this galaxy in the Carnegie-Irvine Galaxy Survey gives a galaxy diameter, corrected for inclination and the effects of extinction, of 6.82 arcminutes, measured out to the 26.5 B magnitude per square arcsecond Isophote (this is a very-very-low level of surface brightness)
( Carnegie-Irvine Galaxy Survey:
http://cgs.obs.carnegiescience.edu/CGS )

Data associated with the paper Pierce & Tully, 2000, ApJ, 533, 744, and published in http://edd.ifa.hawaii.edu (http://edd.ifa.hawaii.edu/) ,'
gives an observed (uncorrected) radius, out to the same low level of surface-brightness, of 3 minutes and 23 arcseconds, for NGC 5643.

I can still remember "way back when" in 1991, when just about all of the data that you could find about a specific galaxy was found in two or three Galaxy Catalogs and two or three Atlases of Galaxies, which you mostly looked up in the paper (physical) version of the catalog or atlas. There was also a lot of other "hidden" data about a galaxy, but it was not accessible, as it was stashed away in observatory archives all over the planet.

As is, I just spent 6 hours on the internet, looking at numerical data about NGC 5643, and I still haven't looked at all of the available data!

best regards, Bad Galaxy Man

[Andrew Pearce]

Hi Robert

As with most things, it's not straightforward! The relationship between the visual magnitude a visual observer sees and a Johnson V mag does depend on the individual observer! Obviously this is far from ideal. However about 14 years ago, the AAVSO performed a study to try and quantify this relationship amongst a whole bunch of observers. An excellent paper was written by R.H Stanton entitled "Visual Magnitudes and the 'Average Observer':The SS Cygni Field Experiment" which was published in the Journal of the AAVSO back in 1999. It is freely available on the web if you do a Google search you'll find it. The average correction between visual and V magnitudes was found to be:

visual mag = V + 0.210 x (B-V)

I haven't applied this to the estimates of SN 2013aa as I haven't checked whether there have been an B mag estimates made.

The article also goes on to note that "random errors on the order of 0.2 magnitude can be expected when data from many observers are combined".

Anyway I hope this helps.

Regards
Andrew

[madbadgalaxyman]

Thanks for that, Andrew.
Your useful answer saves me a lot of time , as I am fully occupied ("up to my neck") in large quantities of data about NGC 5643!

The combined error of 0.2 sounds about right for the AAVSO observers' visual data about the apparent magn. of 2013aa, as long as one ignores statistical outliers among the scatter of data points...... for instance. there is a cluster of visual observations near 11.1 to 11.2 visual magn. which I think should be ignored in calculating a mean magnitude of the SN. Perhaps these observations are the result of the sort of "wishful thinking" and "cognitive-perceptual bias" that I mentioned; these observers perhaps wanted the SN to be closer to magn. 11
While I am not particularly statistically savvy, I do look at a lot of numerical galaxy data, both the good and the bad and the ugly, so I have a good feel for the sort of bad data points that should be rejected in an analysis.

Perhaps AAVSO should be less "democratic" and only accept estimates from the most accurate visual observers!! It is, after all, possible to measure the average error of a specific observer.

cheers, Robert

"Science is not about democracy, or about sympathy for the underdog or for the weaker workers. It is about getting the best and most hard-working people to throw 'everything they've got' at a difficult problem"
- madbadgalaxyman

[Terry B]

As most people know, the weather has been very crappy for the last 3 weeks. This has stopped me getting any follow up spectra of this SN.
On 5/3/13 I had a partly clear evening but with 20-30kt winds to make it difficult.
I achieved about 15 min of exposure only and even then the star was jumping all around the slit so only about 1/2 of the time was anything being registered. Despite this I obtained a noisy spectra. It shows some progression of the shape of the spectra.
See http://users.northnet.com.au/~bohlsen/Nova/sn_2013aa.htm

Cheers

Terry

[Terry B]

Better weather last night and I took 45 mins of spectra. It now matches a +19 day type 1a SN
see
http://users.northnet.com.au/~bohlsen/Nova/sn_2013aa.htm

Cheers

Terry

[Greg Bock]

Thanks for the update Terry, still raining and cloudy here in Brisbane.

[Merlin66]

Terry,
Once again, congratulations on the excellent results you're obtaining from the LISA.
Well done! It's great to see the continuous spectral observations for this nova.

[Weltevreden SA]

Good work on the 2013aa spectra, Terry! Especially given the conditions. If astronomy has a noble tradition like theatre's 'The Show Must Go On,' you are the role model. Your comment re. the 03/10 image's relation to a 1a in its 19th day got me to wondering if there are standard spectral charts astronomers employ to compare the chronological and line variation intensities as a 1a progresses through its cycle for folks like you who keep your grating on their pulse, so to speak. If such exist and are available for 1a SNe, might they also be available for 2b SNe, etc? Further on the nitty-gritty aspect, is there a document or reference that details how individual line intensities vary over the cycle so we could see with our own eyes which chemical abundances are being seeded into the local ISM as they occur?

[Merlin66]

Dana,
The book you need is Gaposchkin's "The Galactic Novae" - a bit dated now, but still full of very good info. Kaler's "Stars and their Spectra" does a good job of explaining the development of nova...
The attached image gives a quick overview of the various nova type spectra.
HTH

[Terry B]

Another spectra from last night. Now it fits with a 27 day type 1a SN.

Dana
I am using the Gelato database for spectra comparison. It automagically compares an uploaded spectra with their database of SN.
There is also another program called SNID
http://www.oamp.fr/people/blondin/software/snid/index.html
You need to be running linux to use it though.


http://users.northnet.com.au/~bohlsen/Nova/sn_2013aa.htm


Cheers

Terry

[madbadgalaxyman]

Dana,
I have little doubt that the spectral variations with time, and also the light curves, of type Ia SNe have been very intensively studied, as they are of great value in fixing the Extragalactic Distance Scale out to large distances; while Type Ia events are not exactly identical in luminosity, they are nearly so!

One place to start could be a review paper about Type Ia supernovae which was published in the year 2000 by Bruno Leibundgut;
http://ned.ipac.caltech.edu/level5/Sept05/Leibundgut/Leibundgut_contents.html

Cheers,
Robert

[Merlin66]

Terry,
Another good result there!
Well done.
I'm glad you're continuing to monitor this SN....

[madbadgalaxyman]

Hello, Dana, Merlin66, TerryB, and other "spectro-people",

The spectral evolution of supernovae is described in the following review paper from the Annual Review of Astronomy and Astrophysics:

http://ned.ipac.caltech.edu/level5/March03/Filippenko/frames.html

Cheers,
Robert

P.S.

Those spectra look good to me, Terry. Do you collaborate with any professional astronomers on this spectroscopy fascination of yours? From experience, I find that, because of the sheer number of possible objects of observation, and because of the very large number of research "specialties within specialties within specialties" in our grand & magisterial science, amateur astronomers are often surprised by how few professional astronomers are working on a specific problem within astronomy......so it would not surprise me if the spectral evolution of Supernovae was only understood in a "rough and ready manner".

I do agree with Dana that you are a most persistent bloke, and an inspiration to us all.
Because it is all too typical for an amateur astronomer to have plenty of non-astronomical distractions that interfere with their play/work in astronomy, it is always good to hear of success stories about people who "keep on working at it" and who thereby achieve worthwile things.

Line formation and the physics of the materials in space and their emission/absorption of radiation, are described in detail in "Atomic Astrophysics and Spectroscopy" by Anil Pradhan and Sultana Nahar (Cambridge University Press)(2011)(ISBN: 9780521825368). However, this is a "very heavy" book.....I am glad I do have a copy, but this book is more about the atomic astrophysics than the observables (spectra), and a good part of it requires a good graduate-level knowledge of physics.
However, it is not necessary to actually know all of the physics to do worthwile spectroscopy e.g. the spectral classification of stars progressed perfectly well even before people knew how the spectral lines were produced.

Doing classification of objects or spectra is possible and useful work for amateur astronomers; for instance one could learn to classify stellar or nebular spectra every bit as well as a professional astronomer does it.
Indeed, I am very envious of those people who "really know spectra", as there is always the possibility of finding a spectrum that is unusual or weird.
I do know (from personal experience) that it is possible to learn Astronomical classification schemes perfectly, because I have learnt to classify galaxies every bit as well as any professional astronomer, and I am not a PhD in astrophysics!

[mithrandir]

With a bit of violence to the source code and makefiles PGPLOT and SNID will build with CygWin. You need to use gfortran-4 and it still needs some changes. There was something wrong in setjmp/longjmp processing in the PGPLOT code for making PNGs but I've found the fix for that.

It even works with the sample provided.

[Terry B]

Well done.
I haven't even tried. My old linux box doesn't have a screen at present and so I haven't turned it on for some years. I did have Miriad, Karma (for radio data) and IRAF running on it. Maybe I need to try again.
Terry

[Andrew Pearce]

SN 2013aa continues its slow fade. Last night at March 17.69 UT, I made it visual mag 12.9.

Cheers
Andrew Pearce

[Weltevreden SA]

Hi everybody, I just got back from my dark-moon sojourn at Weltevreden Farm here in S Africa. The nearest Internet access is 80 kms away and that place closes at 5:00 in the afternoon and noon on Saturdays. It's nice to hear from somebody besides 300 sheep and a couple of dogs. Robert, I downloaded the Leibendgut paper; thanks much for this & your other referrals. May I recommend to everybody NGC 3603 in Carina? It is practically its own “Guinness Book of Astral Records”—largest HII region associated with a massive cluster, over 2000 solar masses of O and B stars alone, 100 times the ionizing power of the Trapezium, yet a high proportion of sub-solar mass stars that have managed to form in a cloud collapse whose progenitor was 8 times the mass of S Doradus. Yet to look at it visually, it’s about as unexotic as you can find—a pinch of glitter inside a circle less than 60 arcsec dia. I can pick out only about 10 points inside that circle—all 100+ solar-mass O stars, to judge from the scads of info in an literature search. I came across it by accident while reading papers devoted to the cometary appearance of the nearby N3576 nebular complex. Frankly, I thought, “3603? So what?” till I read the arXiv and IOP papers. It has the most exotic C-M plot I've ever seen (attached). Don't you just l-o-v-e it when something you never saw before turns out to be such a Really Big Deal?

=Dana in SA