NGC55 Supernova, Nova, impostor?

[PeterM]

Hi all,

Quick heads up

Found this interesting object in NGC55 in Sculptor last night.
At mag 16.7 its faint for a SN at the distance to the galaxy, so its likely a nova in NGC55, but if it is a SN then its either going to be very bright by tonight or if it stays faint then the pros will want to know why.

We will soon know as lots of pros taking an interest in this one at 6 million light years away.

PSN J00150875-3912501 2014 10 06.48 * 00 15 08.75 -39 12 50.1 16.7 U 177E 62S N55 9 0
Below is a really nice image from Greg Bock last night.

On another note I also recently found what turned out to be a Supernova imposter in NGC7552 (One of the Grus Quartet Galaxies) at mag 17.3 and this is generating a lot of follow up, its one to watch as it could go SN in the next few years. Perhaps the new find in NGC55 will be an impostor also, will soon know.

Anyways NGC55 should make a nice imaging target for follow up, so get clicking!

[astroron (Ron)]

Well done Peter, keep us informed.
Cheers

[malclocke (Malc)]

Spectrum from Gemini south says nova or LBV http://www.astronomerstelegram.org/?read=6548

[PeterM]

Originally Posted by malclocke

Spectrum from Gemini south says nova or LBV http://www.astronomerstelegram.org/?read=6548

Thanks for the link to the ATel.
Just got an email from friends in Chile as well. We suspected Nova most likely and observations last night showed about same brightness as discovery.

[malclocke (Malc)]

Shame it wasn't an SN, that would have been a cracker! Nonetheless, picking up an extra galactic nova is no mean feat, so well done.

[malclocke (Malc)]

Just did a back of the envelope calculation, given:

d = 2200000 pc # Distance to NGC55
M = -19.3 # Absolute magnitude of SNIa
m = apparent magnitude

Distance modulus = 5 log(d) - 5 = 26.7
m = -19.3 + 26.7 = 7.4

an SNIa in NGC55 should be around magnitude 7.4! We will wait for another day

[PeterM]

Thanks for the calculations Malc, now that would have been nice!

[PeterM]

Ad now an ATel with SWIFT obesrvations
http://www.astronomerstelegram.org/?read=6551

[cometcatcher (Kevin)]

Very interesting. I will have to have a go at it when the Moon clears. It's pretty much on the limit of my setup though.

[PeterM]

This will be worth monitoring from here on as it maybe too bright for a classical Nova at that distance. If it turns out to be an LBV or impostor like a SN2008S type event then we maybe lucky in our life times to see a nice bright SN close by.

[Greg Bock (Greg Bock)]

Interesting...advice today from astronomers at Las Campanas is that they were able to take spectra of it at the 6.5m Baade telescope confirming that is a nova with an absolute magnitude M_V ~ -9.2.
Apparently, luminous novae like this are not common so there is a great deal of interest about it in the professional community at the moment.


see here about the Baade scope.
http://www.lco.cl/telescopes-information/magellan/

[gaa_ian (Ian)]

Very impressive find !
I remember several years back a recurrent Nova in Cygnus, bright orange and around mag3 during a Sky tour I was doing.
It takes some explaining to the non astronomer that that bright star they are seeing wont be there in a week or so !

[Greg Bock (Greg Bock)]

Original resolution image here of the new nova at the time of discovery
http://www.astrobin.com/127239/B/

[Derek Klepp]

Thanks Peter I will try and have a go at this with the 16"Dob and Gstar wind permitting

[andyc (Andy)]

I took an image of NGC 55 the other night, and can confirm that the nova has faded a good bit from its peak. It's beyond my set-up now (6" Newtonian and DSLR). But a good imaging challenge, so thanks for all the information, Greg and others!

Greg, let me know if you have any issues with your image being used on my site for the comparison.

A blink comparison between Greg Bock's image and my image is here.

A version of my original image is here

[Greg Bock (Greg Bock)]

Hi Andy,
no problem at all, you can also mention that my image was 21 x 30 seconds, I see that I forgot to add that to the text with the image.

[andyc (Andy)]

Thanks Greg, and I'll do that.