Heliocentric correction

[Andrew Smith]

Not withstanding specific campaign requirement is it standard to correct spectra for heliocentric velocity? Specifically I am think of my echelle spectra at R ~ 9000.

Also is R ~ 9000 considered medium or high resolution?

Thanks Andrew

[Robin Leadbeater]

Hi Andrew,

I dont think there are definitive right answers to these questions

The "BeSS standard" is to not heliocentric correct (and also leave tellurics in so that the wavelength calibration can be verified) As long as you include the observatory location in the fits header though it does not matter because the user can always do the correction. This was a potential problem with ISIS until recently when the new location keywords were added. There are many published amateur spectra in the ARAS archives which cannot easily be corrected as the observatory location is not included in the header. If the observatory location is not included (or well known and published somewhere), my view is the spectrum must be heliocentric corrected as this cannot be done subsequently.

There are no hard and fast rules on resolution categories. I would say R~ 9000 is "amateur high" but "professional medium" (some professionals call my R ~15-20k LHIRES spectra medium) I tend to think of sub angstrom resolution as being high for amateurs (so R > 6500 at H alpha for example) and > ~5A resolution (R <1300 at H alpha) as low resolution but that is only my classification

Cheers
Robin