SN2009K in NGC 1620

[Terry B]

This SN was found on 14th Jan. I took an image of it last night. I haven't tried to measure the mag yet. The image is north up taken with my ST9E unfiltered- 2min exp.

[renormalised (Carl)]

Well done!!. If you've got detailed star charts for that area you should be able to estimate its magnitude based on the surrounding stars.

Or, if you know what type of supernova it is, and how far away the galaxy is, just plugged the numbers into the distance modulus equ' and you'll have a reasonable answer.

[Terry B]

I have measured the flux of the SN but the problem is getting reasonable comparison stars. The image was taken with no filter so this significantly reduces the accuracy I can achieve. I did a comparison to one of the field stars that wasn't saturated (ASAS143624-0005.8) with a V mag of 13.557
This gives a measured mag for the SN of 16.361.
This is pretty rough as there is no colour correction and the error of the ASAS star is about 0.15 mag.
Using the USNO A2 catalogue I get 14.62
It seems to be much harder to measure the mag of these objects in faint fuzzies compared to variable stars.

[renormalised (Carl)]

I worked out the apparent mag of the supernova as 14.96...using the equation d=v/H, where d id the distance to the object, v is the recessional velocity (in Kms) and H is the Hubble constant (which I took as 71kms/mpc). I found the distance and then plugged the absolute mag for a supernova (around -18.5) and the distance into the distance modulus formula...m-M=5logD-5, m= apparent magintude, M=absolute magnitude and D= distance to object.

[PeterM]

Hi Terry, if you haven't done so already try the link below to the Bright supernova page, then in the left hand column you will see Photometry Reference Images. Click on that then pick the galaxy you want ie NGC1620, and you will find a DSS image on which Odd Trondall has noted a number of close stars blue and red mags that are handy to make comparison estimates. If you haven't already try Astrometrica - shareware with a 100 day trial http://www.astrometrica.at/
Bright Supernova page - an excellent resource for Supernova hunters.
http://www.rochesterastronomy.org/SNIMAGES/
PeterM

[Terry B]

Originally Posted by PeterM

Hi Terry, if you haven't done so already try the link below to the Bright supernova page, then in the left hand column you will see Photometry Reference Images. Click on that then pick the galaxy you want ie NGC1620, and you will find a DSS image on which Odd Trondall has noted a number of close stars blue and red mags that are handy to make comparison estimates. If you want to do your own estimates try Astrometrica (if you haven't already) - shareware with a 100 day trial http://www.astrometrica.at/
Bright Supernova page - an excellent resource for Supernova hunters.
http://www.rochesterastronomy.org/SNIMAGES/
PeterM

Thanks.
I got the info about the SN from that page and tried to use astrometica also. I didn't realise there were mag estimates on the pics. This is very good.
I have great trouble making astrometrica plate solve. I can plate solve with no problems using Iris or AIP4WIN so know very precisely the centre of the image- still astrometrica won't work.
The main problen I found was selecting just the SM from the core of the galaxy. This obviously takes practice.