spectro-aras.com

Spectrum for 2014-07-05



Tim

New observations for 16 and 17 july.

16/7: Lhires III with 150 l/mm grating (R~650)



17/7: Lhires III with 1200 l/mm grating (R~5000), [O III] doublet region



Radial velocity of [O III] 5007 line:



Paolo

Nice spectrum...

I waiting next week to OHP spectro meeting to do some spectra of this Nova. (first time since more than 6 month).

Olivier GARDE

Olivier, It's been almost a year since we knew about this transient in Delphinus and you took the first great spectrum! Would be very nice to observe it all together from OHP...

See you in a few days!

Paolo

Here's a spectrum taken last night at OHP spectro workshop with a LISA and C14.
12 exposures of 300s = 1H total exposure



and a comparaison with a spectrum taken by François TEYSSIER 7 months ago.

Is anyone attempting a flux calibrated spectrum at OHP this week? I have had a query from Arne Henden who is interested in the effect the very dominant O[III] line may be having on V mag photometry

Thanks
Robin

I took a spectra of this nova last night. The first for me for this year. I can flux calibrate it and post it if you like.
Terry

Thanks Terry,

That could be useful. To prove Arne's point (which I believe is that the accuracy of the Vmag photometry data may be being affected by the exact response of the photometry setup) it would need to be spectrophotometric ie taken with a wide slit and fully corrected for atmospheric extinction rather than calibrated using Vmag

Robin

Robin Leadbeater wrote:Thanks Terry,

That could be useful. To prove Arne's point (which I believe is that the accuracy of the Vmag photometry data may be being affected by the exact response of the photometry setup) it would need to be spectrophotometric ie taken with a wide slit and fully corrected for atmospheric extinction rather than calibrated using Vmag

Robin

That could prove tricky due to the low altitude. I did take BVRI mags and have created a plot below.

Terry

Robin,

That's an interesting question. I use an Astrodon V filter which has a significantly higher transmission at the [OIII] wavelength than the Bessel V which is used in ISIS for the V mag-based flux calculation. The Bessel filter transmission at the [OIII] wavelength is only 65% of the transmission of the Astrodon filter. When I convolve my recent spectra of V339 Del with the Astrodon filter profile, it reduces the intensity of the [OIII] line to 70% of it's original level but that wavelength is right on the edge of the filter profile where the gradient is large. A small change in the profile of the filter being used will potentially make a large change in the contribution of the [OIII] line to the overall magnitude being measured.

For this reason I am using the actual profile of my Astrodon filter, which I use to measure the V mag at the same time as taking the spectrum, to flux calibrate my spectra rather than the Bessel profile in ISIS.

David