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Terry,
It is always comforting when different instruments, observers. locations and conditions give supporting results

Christian,
I thought my urban imaging conditions were poor but when I see (top photo) the amount of street light you are subject to then I don't feel so bad ... and, also considering the low altitude, your results are remarkable!

I think it is interesting to examine the 'bonus' spectra of the NGC1365 core, an AGN galaxy with some useful emission lines, around 60M ly distant. With only the two nebular [OIII] and Hb lines it is possible to determine the galaxy's distance, nebular excitation class and interstellar extinction.

Even though I've been taking spectra for a few years it never ceases to amaze and impress me that spectra from 'simple' backyard equipment can reveal so much about such distant worlds.

Cheers, Bernard

Hi Bernard,

very nice spectrum. Your caption is somewhat ambiguous. On one hand you write that the spectrum is not instrument response corrected, on the other hand you calculate interstellar extinction. As far as I know interstellar extinction is calculated from the Balmer decrement (ratio of H-alpha to H-beta) using an instrument response and atmospheric extinction corrected spectrum. How did you calculate it? I agree with you, an interesting object.

Regards, Martin

Hi Martin,

I'm sorry about the confusion. The reason the displayed spectra isn't corrected is that the instrumental response curve I have stops just before Ha and if used then that emission line doesn't appear. I didn't realise this at the time and need to make a new one. To calculate the Balmer Decrement I certainly did make manual corrections for the instrumental response, which is flat in the Ha zone. Atmospheric corrections also applied.

Cheers, Bernard

Bernard.
I agree the "bonus" spectrum is interesting. I have't graphed it but interestingly on the raw images the Ha line is clearly distorted and shifted depending on how far from the centre of the galaxy it is measured. I will post a pic later when I'm at home.
Cheers
Terry

Hi Terry,

Unfortunately I was only able to capture the Ha emission very close to the edge of my image (below), but I do see a small degree of curvature towards the blue each side of the main spectral line. If this is what you are referring to then I guess one explanation could be that the hydrogen emitted from the two galactic arms are at a slightly higher RV than the core, which I find hard to understand as the galaxy is virtually face-on to us. Cheers, Bernard

I had better success last night and was able to take about 80 minutes of spectra with my LISA.
A comparison spectra is here

Bernard.
Below is a crop of the region around Ha of the raw spectra of the core of the galaxy. There is certainly some asymmetry. I agree that this is strange as it is a face on galaxy. Any suggestions?

Terry

NGC 1365 is a Seyfert Galaxy so out of plane jets perhaps?

Robin

Hi Robin,

It wasn't that obvious in my 'off the edge' image of Ha, which looks more symmetrical, but in Terry's it is clearly asymmetrical with a blue shift on one side of the main spectra and maybe a small redshift on the other. Based on this I think you are right in suggesting an off-axis jet, possibly a Seyfert 2 rather than a Seyfert 1 or Blazar galaxy, as the black-hole/jet axis doesn't have to be normal to the galactic plane.

I came across the following ATT 6df spectra, which also shows the [NII] 6584A emission close to Ha. Interesting stuff.

Cheers, Bernard

Terry, Bernard, ...

I propose to centralize NGC 1365 SN spectra in a special page on ARAS.
The object is peculiar (very fast change of color index) and can evolve to
a bright object (V=12 for the moment). Intensive spectra collection by
southern observer is welcome. Send your FITS processed spectra to my
personnal e-mail adress (christian.buil-at-wanadoo.fr).

Christian

OK, Ill send you the spectra directly.
cheers

Terry