Nova delphini spectrum using a grating

[robbieince]

We managed to image the nova in Delphinus on Sunday morning, with our 505mm planewave and a 100l/mm grating

It shows the absorption and emission lines clearly. Also a view of vega at the same setup. Not bad eh.....

[Graham Darke]

Thats great. Do you know what the bright emission line on the far right at about 2400 on both images is caused by Rob?

[robbieince]

Hi - that's the Undiffracted star image - nova on top vega below

[mikeyscope]

Some real science down there in Galloway .....interesting stuff Rob, what manufacturer / grating setup was used?

Mike

[Merlin66]

Rob,

I assume you used a DSLR....

What was the spacing between the grating and the CCD chip?

It's convention to display the zero order at the left and the spectrum on the right - this then gives the blue region on the LHS of the spectrum - easier to calibrate...

Mike,

The 100 l/mm grating will be the Star Analyser grating from Paton Hawksley.

[mikeyscope]

Thanks for the info Merlin ....an area of astrronomy I find interesting but looks like much to learn ...and a few pitfalls to overcome I've no doubt!

Mike

[robbieince]

Merlin and Mike - thanks. Yep - a dslr (canon 500d) with about 100mm standoff, from a star analyser gating from PH.

I was thinking of trying to actually calibrate the spectrum with vega - any pointers to make that a bit more automatic?

[Merlin66]

Rob,

You either need to consider Tom Field's commercial package RSpec, or Valerie's freeware VSpec for the processing and calibration of your spectra.

An A star like Vega makes this easier as the Balmer lines of hydrogen are well visible and can allow you to calibrate wavelength/ pixel.

If you use the same set-up for your target star then you can apply the same results (zero order and dispersion) to calibrate an unknown spectrum.

The next stage is to prepare an instrument response calibration which applies the corrections to you raw spectrum.