Nice pic! and another discovery for BOSS! congrats! I had no idea, I have been consumed by work and not following IIS. Wish I could take a shot of it, but it's just been cloud cloud cloud here.
Thanks Roger, same here, it's just cloud, cloud, and even more cloud!!
According to the posts in the Visual Observing forum, we did have one definite & strong visual detection of the SN by the noticeably "eagle-eyed" Paddy..... at a dark sky site, using his 16 inch.
Ron (astroron) was able to see the SN, on and off, with his 16 inch...... but the visibility of the object was strongly dependent on the large variations in the size of the stellar seeing disk.
Ron, in the visual observing forum, estimated that the SN may have a visual magnitude of 14.8 or fainter, which is in accord with my theoretical calculations in the Science forum.
These two blokes are skilled visual observers of vast experience, yet they did not find the SN to be an easy object.
There is an extant magnitude estimate of 14.1, by Joseph Brimacombe at the www.rochesterastronomy.org/snimages supernovae site, but in my and Ron's view, this appears to be an infrared magnitude, and an infrared magnitude relates in no meaningful way to the visual magnitude and visual appearance of this object.
Brimacombe seems to have been using infrared magnitudes for his comparison stars, which is a very odd thing to do.....is there any way you can check on this, Greg?
Yup Robert, I think this is at the limit, rather hoped it would brighten a bit. So then how privileged are Paddy and Ron to be perhaps the only persons on Earth to have visually observed this. Its been a while since I visually looked at a SN and it's great to see dedication in the visual community in view of the onslaught of imagers, congrats guys!
Agreed, Pete, that the SN is not exactly burning out the retinas of our visual observers.
But, keep persisting with your observations, folks!
If the light curve is typical of other type II-P supernovae, the visual brightness should stay almost the same for a long time.
Looks like the weather isn't going our way, so rather than wait for more clear skies, I have posted my first attempt at a long exposure image of SN2011gv anyway. This was taken with cloud drifting in and out of the field several times.
It was taken on 20 October, 3 days after discovery.
Details are:
Camera: ST10XEi, Binned 1 x1, 32 x 30 second subs, no filters.
Scope: Meade 14" LX200R with Optec F7 focal Reducer at 2450mm FL, on Losmandy G11.
It seems to be slowly clearing around here so maybe I will be able to image it again tonight with some luck. If I do I'll do exactly the same exposures so it will be easier to compare if it remains as bright as last time.
It seems to be slowly clearing around here so maybe I will be able to image it again tonight with some luck. If I do I'll do exactly the same exposures so it will be easier to compare if it remains as bright as last time.
I managed one image tonight and it seems as bright as it was last Friday. Very subjective measure but for what its worth.
Greg.
Greg
I was meaning BVRI filters. Just a V filter which is a green filter is pretty useful. You take an image of the SN and surrounding stars that has a maximum value that is in the linear range of your CCD. For an antiblooming CCD that is usually about 50% of the max ADU of the camera.
Then using the known magnitude of one of the field stars you can measure the magnitude of the CCD. These mags can come from various sources.
Even using a green filter that you already have you can demonstrate the changing magnitude of the SN as long as you measure the same comparison star.
Dear Greg
I took your image posted earlier and inverted it. I have marked a star that has a photometry measurement from the Loneos catalogue. It was the only easily obtained comparison star I found. It is V= 11.74 and B= 12.42
It is a bit bright compared to the SN but gives the idea.
Dear Greg
I took your image posted earlier and inverted it. I have marked a star that has a photometry measurement from the Loneos catalogue. It was the only easily obtained comparison star I found. It is V= 11.74 and B= 12.42
It is a bit bright compared to the SN but gives the idea.
Thanks Terry.
Quote:
Originally Posted by jjjnettie
Amazing stuff!
Congratulations Greg on IOTW and
congratulations Greg on your discovery!!
Cheers JJ. I hope IISAC was fun, not too much rain?
Here is my result from tonight with the 12" Newt.
Focus and seeing terrible. A very poor comparison.
Your image is incredible Greg, and congrats Greg Bock on the
discovery . IOTW...awesome!
Thanks jjj and Steve
with the benefit of hindsight, I should have spent the last few days at Lostock, clouds seem to be getting worse here, and preventing me from getting a nice colour pic of the galaxy.
To all thinking of imaging it, give it a go, its relatively bright, and being a type IIP, it should have a nice leisurely drop off in brightness over the next few months.
Here is my result from tonight with the 12" Newt.
Focus and seeing terrible. A very poor comparison.
Your image is incredible Greg, and congrats Greg Bock on the
discovery . IOTW...awesome!
Steve
Cheers Steve. Its been cloudy pretty much ever since.
Quote:
Originally Posted by Greg Bock
Thanks jjj and Steve
with the benefit of hindsight, I should have spent the last few days at Lostock, clouds seem to be getting worse here, and preventing me from getting a nice colour pic of the galaxy.
To all thinking of imaging it, give it a go, its relatively bright, and being a type IIP, it should have a nice leisurely drop off in brightness over the next few months.
Greg I'd love a bit of a writeup about what type of star does this, how big is it, how much energy is there in these explosions and over what area of space does this extend. It looks brighter than the galaxy itself and would appear to be very dangerous to be anywhere near it. Radiation alone from an event like this must be dangerous to life.
Greg I'd love a bit of a writeup about what type of star does this, how big is it, how much energy is there in these explosions and over what area of space does this extend. It looks brighter than the galaxy itself and would appear to be very dangerous to be anywhere near it. Radiation alone from an event like this must be dangerous to life.
Greg.
Greg,
I could estimate the luminosity (absolute brightness) of this SN without too much trouble, but first I need some good estimates of its apparent magnitude.
In my opinion, The SN looks brighter than the central bulge component of this galaxy, but it is likely to be well fainter than the total light of the galaxy itself, which also includes a vast region of very faint spiral arms.
The average type II-P supernova comes in at around a Blue (B-band) luminosity of about 600 million times that of our own Sun, but individual II-P supernovae differ greatly in luminosity (by a factor of up to 6 or more)
Best Regards,
Robert
Last edited by madbadgalaxyman; 01-11-2011 at 10:23 AM.
Reason: typo
