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Supernova Sn2011b and Galaxy Ngc2655

Doc

By Doc
in Observing - Reports

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Doc

Doc

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Just spent the last couple of hours observing the supernova Sn2011b within Ngc 2655 in the constellation Camelopardalis.

It is a Type Ia Supernova, which means it is an explosion of a white dwarf star.

It took me a good 30 minutes to find it, and I done so by star hopping from M81/82, but once I did I could see the galaxy with direct vision, it was pretty dim but I could still make out the elongated oval shape and also a slight core was visible.

The galaxy resembles your typical 12th magnitude galaxy and it's 5.1' x 4.9' in size. It lies 71 million light years away.

Just within the galaxy's halo I could detect a star like object of at least mag 13, it's position was about 240° or in 8 o'clock position. This is of course the supernova Sn2011b.

I was using my Meade Lightbridge 16" scope with the 28mm and 16mm William Optics Uwan eyepieces, each eyepiece was used in conjunction with the Baader Light pollution filter.

I managed to sketch the galaxy Ngc 2655 and supernova SN2011b with both eyepieces and will scan these in tomorrow.

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Hypernova

Hypernova

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Good work on tracking it down, I can't wait to see the sketch to see how it compares to my view through the dob :)

I star hopped from Polaris and followed some random asterisms and some of the brighter stars in the area to get to the right place.

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russ

russ

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That's excellent work Mick. Really like the sketch.

One question: was this from your dark sky site with the East Midlands group or from the garden?

Just trying to workout whether i waste an hour or so trying to find it in the 12".

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Doc

Doc

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It was from my garden with about mag 4.5 skies. To be honest it was maybe a tad dimmer then what I sketched, a bit hard to get it exact of course and with prolonged observation, you begin to see the object brighter as well.

But it was defintely easy to see when you eventually find it as there are no real markers to show you the way.

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mdstuart

mdstuart

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Doc

I also did a thread on this in the heads up. I also sketched it and guessed a mag of 12.8 for the SN based on stars nearby 3UC - 337 022 143 and 3UC 337 022191.

So amazing to see this was it not!

NGC 2655 is one of the brighter galaxies but as you say a bit of a challenge to locate.

Well done on spotting it as well...

Mark

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mdstuart

mdstuart

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Interestingly comparing our sketches you have less stars showing. I have three faint stars in a row between the two brighter stars in your sketch. These show down the bottom of this chart.. The faintest star I could see was on the other side of NGC 2655 noted on Carte Du Ciel as mag 14.4. This faint star is marked on the attached JPEG with the arrow.

My skies must be better than yours?

Mark

post-14100-133877523378_thumb.jpg

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DarkerSky

DarkerSky

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That's brilliant, Mick. Well done on tracking it down. It's a wonderful sight, and quite mindblowing to think that we are witnessing a 'live' event that happened 71 million years ago !!

I have read a figure of 64 mly too for NGC 2655, so I guess there is a bit of discrepancy between sources

Mark - I think I caught a glimpse of that Mag 14.4 star you mention in my 12" last night. Unfortunately I had high cloud scooting in so couldn't confirm everything I was seeing in my FOV, but I did suspect a 'possible' fainter star fairly close in on the other side of the gx.

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DarkerSky

DarkerSky

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Nice work Mick. I don't think I stand much chance of finding it with my 9.25" especially through the ever present clouds.

Dave

If we were to ever get a clear sky again(!) I think you'd do fine, Dave. Tom (Hypernova) got it in his 200p. Anything over an 8" would pick it up I'd imagine. The SN is about mag 12.5 in brightness and the galaxy has a fairly high surface brightness.

Just need those pesky clouds to go away :)

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acey

acey

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Wow, I hadn't even heard of it until I saw this thread so thanks guys! The following link has info and pics:

Supernovae 2011B in NGC 2655

There are reports of it having been seen with a 4" refractor in a moonlit sky with limiting mag 4! We may have about a week to go before it starts fading. (Apologies if this repeats information already posted elsewhere that I missed).

post-14602-133877523741_thumb.jpg

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mdstuart

mdstuart

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Acey you are clever so using the mag 13.8 as the brightest point on the curve and assuming it is a type 1A supernova I gather there is a formula using the absolute mag of a 1A SN that will give a distance. How does this compare to the 60-70 million light years for NGC 2655....?

Mark

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acey

acey

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Good point Mark! Someone fetch an astrophysicist...

(Apparently the absolute blue luminosity of a Type 1A is -19.6 at peak. So it's a case of getting the peak blue luminosity of this one then doing the maths).

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