chi Cyg how to correct?

[Gasman]

Guys

I did this spectrum of chi Cyg the other evening and wondering how to create an instrument response curve for it as Sinbad lists it as a S6-9 type star and I don`t have any S type reference curves in the software?.

Thanks

Steve

[Merlin66]

Steve,

My answer....don't!

Use a standard A type star to generate the Instrument response then apply that to your spectrum..

[robin_astro]

Steve,

My answer....don't!

Use a standard A type star to generate the Instrument response then apply that to your spectrum..

Indeed. Where is the value in taking a star's spectrum then forcing it to look like "the one in the book" ?

And further to this, for best accuracy, try to measure your reference star as near as possible to the same time, elevation and part of the sky as your target to minimise atmospheric extinction effects, preferably using a star with an actual published spectrum (eg one from the Miles database) rather than a generic Pickles spectrum which can differ from the actual spectrum of the reference star you choose for a whole host of reasons. (Essentially like doing diferential photometry, which is effectively what we are doing in spectroscopy but simultaneously at hundreds of different wavelengths)

Cheers

Robin

[Gasman]

Thanks guys but now I`m a little confused I thought we had to correct for instrument response to rule out the differences in our optical setups ?

Steve

[Merlin66]

Steve,

Yes....if we use different set-ups and change telescopes/ gratings/ distances/ cameras every time.

If you are using EXACTLY the same set-up night after night, then the instrument response shouldn't change.

Get a good instrument response from the A type star (neglecting atmospheric effects for the moment) and that should see you through.

Do you agree??

[Gasman]

See what you mean Ken but on one of Toms Rspec videos he suggests having a different response curve for each class of star implying I think that a curve created using say Vega would not suffice for all the other groups, unless I've read that wrong ( which is more likely!)

Steve

[Merlin66]

Steve,

To meet your needs, one instrument resoponse curve will do the job.

Try it.

[Gasman]

Hows this look Ken, corrected using AOV curve

cheers

Steve

[Merlin66]

Looks better.

It shows the typical rising of the continuum towards the red associated with the cooler M class stars.....