Nova Del animation

[jnp]

I have tried presenting these Nova Del 2013 spectral animations in two different ways.

For the first animation, the spectra are scaled for a consistent continuum. This shows the relative strengths of the Hydrogen Balmer lines

The spectra in the second animation are scaled to have the same Hydrogen alpha peak. This shows the continuum variation.

If anyone has any photometic measurements of the H alpha peak I could re-scale accordingly to fit to get a more realistic result?

Thanks for looking

John

[WaveSoarer]

That's brilliant. Very nice indeed.

[robin_astro]

If anyone has any photometic measurements of the H alpha peak I could re-scale accordingly to fit to get a more realistic result?

Thanks for looking

John

Hi John,

Flux calibration of spectra  is rather tricky and is only recently being attempted. There are a couple of possible approaches

1. Calibrate the spectra in absolute flux against standard stars. see this page by Christian Buil

http://www.astrosurf.com/buil/calibration2/absolute_calibration_en.htm

2. Use V mag photometric measurements (eg from AAVSO) compared with the result from integrating the spectra over the Vmag passband. I used this second method on Nov Del to calculate the change in absolute flux (in arbitrary units) in the H alpha line here

http://www.spectro-aras.com/forum/download/file.php?id=1169

from this thread

http://www.spectro-aras.com/forum/viewtopic.php?f=5&t=682&start=190

It needs updating but shows the H alpha intensity rising and then levelling out in absolute intensity as the continuum falls away

Cheers

Robin

[jnp]

Hi Robin,

Thanks for this.

I was thinking along broadly similar lines about relating the area under the spectra to magnitude measurements. This can then calculate a correction factor to scale each spectrum. Just got to figure out how to actually apply this. This is not as easy as it seems!

kind regards

John  
 

[Gasman]

Looks very impressive John, must find the time to have a go at an animation:-)

Steve

[robin_astro]

Hi Robin,

Thanks for this.

I was thinking along broadly similar lines about relating the area under the spectra to magnitude measurements. This can then calculate a correction factor to scale each spectrum. Just got to figure out how to actually apply this. This is not as easy as it seems!

kind regards

John  

Hi john,

Hopefully there will be a writeup on the  method using photometric magnitudes  in the near future (I am working on it with Martin Dubbs and ironing out out some fine details. The problems are more with the photometric filter definitions than with the spectroscopy) but yes, the production of absolute flux calibrated spectra is perhaps the last big challenge in amateur spectroscopic processing. 

Cheers

Robin

[jnp]

Ok, here is a third animation I have been working on.  The flux scaling of each profile is corrected using calculations involving the flux area and stellar magnitude, (Excel sheet available on request). 

You can see the Nova fading, with the continuum fading at a greater rate than the Hydrogen Balmer lines.

My data is very limited and not helped by switching camera half way.  I would like to see the animation with more data so am appealing for more low res Nova Del data from this forum to create a collaborated result. One stacked FITS spectrum per day would be great.

Thanks for looking

John 

[michael.h.f.wilkinson]

Very nice. I will show this to some astronomers (Kapteyn Astronomical Institute) I work with, they'll love it.

[robin_astro]

Hi john,

Hopefully there will be a writeup on the  method using photometric magnitudes  in the near future (I am working on it with Martin Dubbs and ironing out out some fine details. The problems are more with the photometric filter definitions than with the spectroscopy) but yes, the production of absolute flux calibrated spectra is perhaps the last big challenge in amateur spectroscopic processing. 

Cheers

Robin

Here is the description of the procedure with an animation by Martin using data from the ARAS database

http://www.spectro-aras.com/forum/viewtopic.php?f=5&t=682&start=220#p3099

see post entitled "flux calibrated animation"

The direct link to animation is here

http://www.spectro-aras.com/forum/download/file.php?id=1206

Remarkably there are now over 800 amateur spectra of this object so far in the ARAS database

and at this rate will soon overtake the previous record of a single campaign (eps Aur)  though that took several years rather than a few weeks

Robin