Spectroscopy

[sheeny (Al)]

Originally Posted by robin_astro

Hi Al,

It does look suspiciously like a Telluric line. Compare for example Christian Buil's annotated spectra of Vega
http://astrosurf.com/buil/us/vatlas/vega3.gif
http://astrosurf.com/buil/us/vatlas/vega4.gif
from this page
http://astrosurf.com/buil/us/vatlas/vatlas.htm
Was the spectrum taken at a lower elevation compared with the others (higher air mass)?

Cheers
Robin

G'Day Robin,

No. The other Galilean Moons were captured at essentially the same time. Separate images for each to optimise exposures, so Ganymede was the shortest exposure of the 3. Callisto was the longest exposure, but this line doesn't show there, and it doesn't show in the Io/Europa conjunction spectrum either. That's the puzzle...

I'll just have to do it again. It would be interesting to see what other's get if anyone wants to have a go too. It won't hurt to do it at higher elevation anyway... I guess it was about 45° elevation when I captured these.

Al.

[Merlin66 (Ken)]

Again from memory, the profiles were under Nick Glumac's chapter in PAS...his 2 spectroscope designs, I think the Hi dispersion section....

[sheeny (Al)]

Originally Posted by Merlin66

Again from memory, the profiles were under Nick Glumac's chapter in PAS...his 2 spectroscope designs, I think the Hi dispersion section....

Yeah I found them, thanks Ken. There wasn't anything there of use. I'm part way through browsing Kaler again.

The other thing I found the other day was a Molecular Spectrum database... there heaps of data in the IR band, but I'll have to find the URL (I found it after giving up on the NIST Moleular database) and work through it methodically for the visible / near IR band. I found I could get simulated spectra out of it, but the data is bogged down with lots of extra stuff that we don't need to construct an artificial spectrum for Vspec. I need to spend more time working out the best way to extract what I need.

I suspect it is a telluric line, but why it appears in this spectrum and not the others defies me. I need to repeat it for that reason.

Al.

[Terry B]

I haven't been using my Sa much recently but I did take some images of Nova Sgr2009 no3 on 13th August. At the time it was V mag 9.66 and R mag 8.61.
The spectrum is a composit stack of 5 frames of 20 sec exposures.
It is very low res at just under 32A/pixel.
The Ha dominence is very obvious.

[Merlin66 (Ken)]

Very nice!!!!
Just goes to show what can be done with a (good!) 8" telescope and a Star Analyser grating.
Here we have an almost 10 mag star spectrum recorded in less than a two minute total exposure.

[Merlin66 (Ken)]

Christian Buil has just published his results from the 10th through the 13th Aug. C11, 2.1A/pixel and exposures from 35 to 90min!!


http://astrosurf.com/buil/nova_sgr2009_n3/obs.htm

[Swanssm (Peter)]

Hey Folks,

I am interested in doing a Blog Post on my blog about amateur spectroscopy, featuring a bit of the local "legenday" IceinSpace talent.

As I don't know much about it myself...I am curious, but also haven't seen much comment on this other than here in Iceinspace.

If a couple of folks are happy to answer a few questions (message me) I'd be keen to do a feature, link to some interesting examples/photos etc & highlight some of your talent.

Just reading though some of your work on this thread sounds like some amazing stuff is going on. If you interested message me with the answers to a few questions and may be provide a quote and or varified "discoveries/interesting work".

Q: How did you get stated?
Q: What equipment do you use? (Basic, Intermediate and advanced)
Q: Examples of "build your own" (websites/photos to link to etc)
Q: Whats your most exciting work so far?
Q: Any examples of where you have collaborated/confirmed professional astronomers etc
Q: What are the limits/boundries/best practices


Peter
SWANSSM
(or as I now like to say Page 79 of the compendium)
aartscope.blogspot.com

[Swanssm (Peter)]

Hi all,

My article has been published on Universe Today. Enjoy....thanks to Ken and those who assisted.

http://www.universetoday.com/2009/11...-spectroscopy/

Keep up the good work!!!!
Regards
peter

[sheeny (Al)]

Well done. Its a good read.

Al.

[Waxing_Gibbous (Peter)]

Thanks for that. I think this is a fascinating branch of astronomy and I've decided to take it up. Your article was very helpful.
Regards,
PJH

[sheeny (Al)]

I've finally managed to get out and capture some spectra again.

This is the first run with a new setup: ED80, SA 100 on the end of an Orion 3x barlow body and the DMK 41AU02.AS. On paper I thought I could get about 4 A/pixel dispersion with this setup if I can achieve focus.

Well I can achieve focus but ATM the focus is not very good... With my C8 and Motofocus I could be sitting at the puter and tweaking the focus. Unfortunately, I'm not that sophisticated with the ED80, and its obviously much harder to get a good sharp focus looking at a screen on the other side of the obs! I think I need an assistant!

Anyway, the dispersion is encouraging. Actually I think the 3.4 A/pixel is better than I calculated (estimating distances etc), I just need to work on focus, and maybe guiding for dimmer objects. If I can nail focus, I reckon I should achieve a resolution of low 20's A/pixel.

ATM I could always go back to the C8 if I want to...

Unfortunately, I can't achieve focus at this sort of dispersion with either the C8 or C11 . The extra aperture would be nice!

Al.

[Merlin66 (Ken)]

Al,
Good to see you've managed to some results.. the weather ( everywhere?) has been terrible!!
The ED80 is a nice instrument, you could fit one of those SW electronic focusers....
Increasing the distance can give some increase in plate scale, but the resolution is swamped by the aberrations. Adding a Grism would help!
Good result though!!
Keep at it!

[Terry B]

I'm been pretty slow at processing this but I took a simple spectrum of the nova in Eri early in Dec. It is designated KT Eri
It is taken with my SA grating that I had put in the filter wheel of my camera. It is too close to the CCD and the result is that the resolution is ~25A/pixel.
At least it gives the idea.

[Heian (Mark)]

Nice one Terry!

It's been so long since I did any sort of spectra collection and analysis, I'm pretty sure I've forgotten exactly how to do it!

cheers
Mark

[Terry B]

Originally Posted by Heian

Nice one Terry!

It's been so long since I did any sort of spectra collection and analysis, I'm pretty sure I've forgotten exactly how to do it!

cheers
Mark

Likewise. I had the analysis program crash about 10 times before I realised I was pushing an incorrect button.
I will try to get a better system going to improve the resolution.

[Merlin66 (Ken)]

Increasing the distance to the CCD chip, as Al has done, will give a marginal improvement. The next step would be to add a Grism, this will reduce the aberrations and improve resolution.
To go further, then we're moving into a collimated design either with the SA or a reflection grating.......

Sitting under 4" of snow at the moment and more to come.....

[sheeny (Al)]

I see SBIG have released a hires version of the SGS with an 1800 l/mm grating:

http://www.sbig.com/sbwhtmls/online.htm

It's in the price list but nowhere else on the web page that I can find.

LHires III must be being felt...

Al.

[Glenpiper (Bernard)]

I think an SGS (not STS) 1800 l/mm grating has been available from SBIG, as a special request, for a long time. I recall reading a few years back that a US amateur (I think it was Dale Mais) had been able to talk SBIG into this.

Bernard

[sheeny (Al)]

Whoops! Fixed the typo now.

I had read in several places that SBIG may release higher resolution grating for the SGS, but I hadn't realised that it had already happened.

Al.