Very deep spectroscopy of the bright Saturn nebula NGC 7009 – I. Observations and plasma diagnostics
in Monthly Notices of the Royal Astronomical Society
July 2011; p ublished online July 2011 .
Journal Article. Subjects: Astronomy and Astrophysics. 13309 words.
We present very deep CCD spectrum of the bright, medium-excitation planetary nebula NGC 7009, with a wavelength coverage from 3040 to 11 000 Å. Traditional emission line identification is...