New Possible Supernova in NGC1365 - Page 9

Terry B · #**161** 01-01-2013, 02:48 PM

A spectra form last night. It is still bright enough for me to obtain a spectra with 1 hr of exposure.
https://gelato.tng.iac.es/plots/plot_S6Ffnl7313J5.png

Terry

LewisM · #**162** 01-01-2013, 03:49 PM

Any new IMAGES? Haven't been able to even think about getting some shots of it for well over a month now, and wondering how it looks now?

Terry B · #**163** 01-01-2013, 04:10 PM

Quote:

Originally Posted by LewisM

Any new IMAGES? Haven't been able to even think about getting some shots of it for well over a month now, and wondering how it looks now?

I took BVRI images at the same time. Ill upload them later
Terry

Terry B · #**164** 01-01-2013, 07:10 PM

Pics from last night. They were taken with a V filter.
The second one is labelled

pvelez (Pete) · #**165** 01-01-2013, 07:39 PM

Terry

I have the LISA set up and ready to go this evening after the sun sets - what V mag do you have for this one?

Pete

Terry B · #**166** 01-01-2013, 08:19 PM

Quote:

Originally Posted by pvelez

Terry

I have the LISA set up and ready to go this evening after the sun sets - what V mag do you have for this one?

Pete

For SN2012fr
V= 14.113
R = 13.794 last night.
I used 600 sec exposures.
To position it on the slit I use 3 sec exposures with my STi guider and this showed it up well enough.

SN2012hr is a bit brighter.
It is V = 13.76
R = 13.74

Cheers
Terry

pvelez (Pete) · #**167** 01-01-2013, 09:49 PM

Quote:

Originally Posted by Terry B

SN2012hr is a bit brighter.
It is V = 13.76
R = 13.74

Cheers
Terry

Cheers Terry - I'm having a go at SN2012hr as I type. As you say, its a bit brighter.

Crossing my fingers - its a cheeky one to find among all those other stars.

Will post tomorrow on the Peter M's other post if I have any luck

Pete

rogerg (Roger) · #**168** 03-01-2013, 12:53 AM

Here's my image from tonight. I now have observations from 22 nights over the SN's life. I'm still not confident I know what I'm doing with magnitude estimating to have bothered graphing them yet.

This is a screen shot from Astrometrica.

It's reported 14.4 is certainly fainter than the mag 12 it was giving me back at the start of my observations, suggesting I'm doing something right with the magnitude estimating.

Regards,
Roger.

Andrew Pearce · #**169** 03-01-2013, 10:47 AM

Hi All

This SN has faded a fair bit now. I visually observed it last night and made it mag 14.8 at Jan 2.57UT.

Regards
Andrew Pearce

rogerg (Roger) · #**170** 06-01-2013, 02:43 PM

Here is my attempt at graphing my observations to date.

Open to comments/criticisms.

I used CCDSoft's "Generate Light Curves" functionality for "Stationary (variable star)". The magnitudes I specified for the two reference stars used were obtained from Astrometrica's values for the reference stars it identified in the image (I couldn't seem to find/click on the stars in TheSky to obtain magnitude that way).

The refernece stars are shown in the attached screen shot from CCDSoft.

Roger.

Merlin66 (Ken) · #**171** 06-01-2013, 03:00 PM

Roger,
Was the red circle shown on the SN, the measuring aperture for the magnitude??

rogerg (Roger) · #**172** 06-01-2013, 03:08 PM

Quote:

Originally Posted by Merlin66

Roger,
Was the red circle shown on the SN, the measuring aperture for the magnitude??

I don't know. There wasn't any obvious way to change the aperture if the aperture is relevant to the method of magnitude estimation CCDSoft uses. I'll see if I can find out any more about how it's done in CCDSoft.

Merlin66 (Ken) · #**173** 06-01-2013, 03:22 PM

In AstroArtV5 you can vary the aperture to suit the star size....
In photometry they recommend a measuring aperture x2 to x3 the FWHM size of the target star.....

LewisM · #**174** 06-01-2013, 03:25 PM

Thanks on the visual images guys.

Terry B · #**175** 06-01-2013, 05:26 PM

Quote:

Originally Posted by rogerg

Here is my attempt at graphing my observations to date.

Open to comments/criticisms.

I used CCDSoft's "Generate Light Curves" functionality for "Stationary (variable star)". The magnitudes I specified for the two reference stars used were obtained from Astrometrica's values for the reference stars it identified in the image (I couldn't seem to find/click on the stars in TheSky to obtain magnitude that way).

The refernece stars are shown in the attached screen shot from CCDSoft.

Roger.

Excellent Roger
It is worth looking for reference star mags from VSP on the AAVSO website. These will almost always be more accurate than TSXP or astrometrica.
The AAVSO has magnitudes for the star to the left on your image these are
B = 15.052
R = 14.295
I = 14.025
These mags have been taken from APASS data that is accurate to about 0.05 mag for mag 14 stars.
I have used the photometry tool with CCDSoft but only for a quick estimate. You don't seem to be able to vary the parameters. There are other aperture photometry programs available that are better. AIP4WIN is a very popular one and reasomably cheap.
Cheers
Terry

rogerg (Roger) · #**176** 06-01-2013, 06:08 PM

Quote:

Originally Posted by Terry B

Excellent Roger
It is worth looking for reference star mags from VSP on the AAVSO website. These will almost always be more accurate than TSXP or astrometrica.
The AAVSO has magnitudes for the star to the left on your image these are
B = 15.052
R = 14.295
I = 14.025
These mags have been taken from APASS data that is accurate to about 0.05 mag for mag 14 stars.
I have used the photometry tool with CCDSoft but only for a quick estimate. You don't seem to be able to vary the parameters. There are other aperture photometry programs available that are better. AIP4WIN is a very popular one and reasomably cheap.
Cheers
Terry

Thanks Terry. Those mags are slightly different to what I was using for that star (14.7) but then I have been using the clear filter rather than BRI so at best I am going to get an approximation regardless.

Ken/Terry .... After doing quite a bit of searching and reading I'm reasonably confident of my understanding that: CCDSoft uses SExtractor. The parameters for it's use are configured via the Photometry Setup dialog which contains attributes for aperture, focal ratio, pixel size and seeing conditions. My understanding is these parameters would be sufficient for determinig appropriate aperture size. The indication to me is that it uses these values for configuring SExtractor for aperture photometry in the background, and that the circles shown around the stars on the image are simply to indicate star selection rather than aperture size. This leaves me with no reason to doubt the method used by CCDSoft even though CCDSoft doesn't seem particularly popular for this type of work (perhaps only because of it's lack of transparency regarding how it works?).

I have so many tools installed for different photometry/astrometry/etc it's easy for them to be lost amongst each other. Sometimes I find it easier to simply try with what I have rather than learn another. For estimating magnitude I've typically used astrometrica. I was tempted to use Astrometrica for this graph but thought CCDSoft would make it easier, as with Astrometrica I need to measure each image individually then manually put them in a table. I may move to something else but I wonder if AIP4Win the best? SExtractor seems to be a highly regarded choice by the pro's. Maxim has similar capabilities to CCDSoft (on the surface at least, I haven't dug in to it's inner workings). Similarly I have MPO Canopus which does light curve analysis too, but have little idea at this stage how it compares for the task.

Out of interest, attached is a result from Maxim.

rogerg (Roger) · #**177** 06-01-2013, 07:43 PM

I've been playing with Maxim some more. It's photometry tool seems very easy to use and quite powerful, as well as having documentation.

I'm still learning ... particularly with regard to what aperture size and annulus size to use, but have a new plot. By changing the aperture down, the estimated mag is quite different, now 14.557 being the most recent reading from last night.