Jupiter high resolution spectrum

[Jack Martin]

Taken 01/01/13 18.08 through Lhires III spectrograph 2400g/mm grating C11 Atik 314L 10 sec exposure around H alpha region.

Thank you to John Strachan for calibrating image in V Specs.

The system needs tweeking.

Any comments?

Jack

[the rev]

Really great HA area image, lots of detail. Never used vspec but trying to learn hoe to use it.

Great work.

Kate

[Merlin66]

Jack,

It's good to see you've got the Lhires up and running!

Well done.

The Ha curve is a great starting point...look forward to seeing your progress.

[Jack Martin]

Thanks Merlin 66,

More to follow but the weather here in London town is cloudy.

Regards,

Jack

[Jack Martin]

Thanks Kate V Specs is not difficult to use the question is which lines are from Jupiters atmosphere?

Regards,

Jack

[Merlin66]

If you remove the telluric lines (earth's atmosphere) and get a similar solar spectrum, you can use that to apply corrections to the Jupiter spectrum.....

[Jack Martin]

Merlin 66,

Thanks for your input I will look into that.

Regards,

Jack

[NLO]

This may be a silly question, but how do you remove the telluric lines?

I've removed G class star from Neptune before to get the spectra, but not the telluric lines

Kate

[Merlin66]

Kate,

This can easily be done in Vspec.

You can call up ( under Radiometry tab) the Atmospheric H20/ telluric line database and scale it to your atmospheric absorption and then divide to remove the atmospheric lines.

This is covered on pages 109-111 of the VSpec Manual....

[Jack Martin]

Merlin 66,

Thanks for pointing us in the right direction.

Regards,

Jack

[the rev]

Thanks Merlin66

[robin_astro]

Hi Jack,

Merlin 66,

Thanks for your input I will look into that.

Regards,

Jack

This is really easy to do. Just point your scope at the sky (not at the sun!) and take a spectrum with the same setup. (Put a cloth or something over your LHIRES to shield it from stray sunlight) You just then divide your Jupiter spectrum by your solar spectrum - job done :-). Because this is high resolution covering a narrow range of wavelength it will not matter that the continuum of the sky spectrum is distorted by the atmospheric scattering (ie the solar spectrum will be too blue of course)

You might even be lucky and find the telluric water lines cancel out too but if not you can use VSpec or ISIS to fo the job

Cheers

Robin

[the rev]

Hi Jack,

This is really easy to do. Just point your scope at the sky (not at the sun!) and take a spectrum with the same setup. (Put a cloth or something over your LHIRES to shield it from stray sunlight) You just then divide your Jupiter spectrum by your solar spectrum - job done :-). Because this is high resolution covering a narrow range of wavelength it will not matter that the continuum of the sky spectrum is distorted by the atmospheric scattering (ie the solar spectrum will be too blue of course)

You might even be lucky and find the telluric water lines cancel out too but if not you can use VSpec or ISIS to fo the job

Cheers

Robin

Hi Robin,

Will this work with a star analyser as well?

Kate

[Gasman]

Nice spectrum Jack :-) Has that been divided by a G2A spectrum at all?

Best

Steve

[Jack Martin]

Steve,

No it has not been divided by a G2V spectrum.

Thanks for your interest.

Jack

[Jack Martin]

Robin,

The Lhires is not attached to the C11 at the moment can I just point the Lhires at the sky to get the required image?

Thanks for your input,

Jack

[robin_astro]

Robin,

The Lhires is not attached to the C11 at the moment can I just point the Lhires at the sky to get the required image?

Thanks for your input,

Jack

Yep that will work, or without the scope you can point it directly at the sun without risk and get a more accurate spectrum (no blue sky effect from Rayleigh scattering) provided your camera can take a short enough exposure. (Remember for best results to subtract darks for both spectra and a sky backgound subtraction for the Jupiter spectrum otherwise zero offset levels could cause problems)

Cheers

Robin

[robin_astro]

Hi Robin,

Will this work with a star analyser as well?

Kate

Hi Kate

Only If you include a slit in the setup eg

http://www.threehillsobservatory.co.uk/astro/spectroscopy_4.htm

More usually a G2V star is used with the Star Analyser though you could record the solar spectrum from sunlight glinting off a needle or ball bearing

(I suspect correcting using a G2V star at high resolution as in Jack's case may not work too well as the match to the solar spectrum may not be that good when looking at the detailed shape of the lines)

Cheers

Robin

[robin_astro]

Hi Kate

Only If you include a slit in the setup eg

http://www.threehill...ctroscopy_4.htm

More usually a G2V star is used with the Star Analyser though you could record the solar spectrum from sunlight glinting off a needle or ball bearing

(I suspect correcting using a G2V star at high resolution as in Jack's case may not work too well as the match to the solar spectrum may not be that good when looking at the detailed shape of the lines)

Cheers

Robin

Sorry, I just realised you probably meant the bit about removing the Tellurics. I tried it a while agowith low resolution spectra and it sort of works but you have to filter the individual lines so they merge into the band we see at th Star Analyser resolution. Also the telluric line database in Vspec is limited in range. An alternative is to make a Telluric band template using our old friend the A type star and use that, scaling it accordingly. You can see how I used this technique here.

http://www.threehillsobservatory.co.uk/astro/Classifying_red_stars_using_a_Star_Analyser_VdS_poster.pdf

Cheers

Robin

[Gasman]

No it has not been divided by a G2V spectrum.

Sorry Jack I meant G2V

Steve

[the rev]

Sorry, I just realised you probably meant the bit about removing the Tellurics. I tried it a while agowith low resolution spectra and it sort of works but you have to filter the individual lines so they merge into the band we see at th Star Analyser resolution. Also the telluric line database in Vspec is limited in range. An alternative is to make a Telluric band template using our old friend the A type star and use that, scaling it accordingly. You can see how I used this technique here.

http://www.threehillsobservatory.co.uk/astro/Classifying_red_stars_using_a_Star_Analyser_VdS_poster.pdf

Cheers

Robin

Thanks Robin will have a look at the web page.

Kate

[jsandse]

Jack,

Unfortunately your spectrum doesn't have a high enough SNR to elicit much information about jupiter from it - well it was only a 10second exposure .

However if you persevere and get longer exposures across the visible spectral range then you can have quite a lot of fun with Jupiter.

You could for instance:

- take full disk spectra of Jupiter to:

- identify the ammonia and methane bands in Jupiter

- derive the temperature of the planet from the thickness of the methane bands

- identify Ramen scattering

- and if you can take spectra of different parts of the planet you can see how the spectra changes relating to the belts,zones and storms on the planet.

A lot of this has been done before by professionals but Jupiter I reckon is probably not particularly well observed at the moment as there are no probes going round it - unlike Saturn which has Cassini. In fact the next mission Juno is on its way and wont be there till August 2016 - and it doesnt have a spectrometer on it which covers the visible region from what I have read. So there must be a good opportunity to make discoveries.

On its way to Saturn Cassini flew past Jupiter and captured some spectra of it which can be seen here:

http://vims.artov.rm...ta/res-jup.html

The papers by Karkoschka which are referred to in the Cassini web page are well worth looking at. The paper records in the process of how to take spectra of Jupiter and the other gas giants in a scientific way from the earth - and describe a good way of processing your data in order to get a nice albedo spectrum of Jupiter.

As always plenty of opportunity for some fun amateur spectroscopy

cheers

John