Euclid prep. XXVII. UV-NIR spectral atlas

To this end, we use the emission lines in the spectra of compact planetary nebulae (PNe), which were selected from a PN data base. To ensure completeness of the PN sample, we developed a novel technique to identify compact and strong line emitters in Gaia spectroscopic data using the Gaia spectra shape coefficients. We obtained VLT/X-SHOOTER spectra from 0.3 to 2.5um for 19 PNe in excellent seeing conditions and a wide slit, mimicking Euclid's slitless spectroscopy mode but with 10 times higher spectral resolution.

Additional observations of one northern PN were obtained in the 0.80-1.90um range with the GMOS and GNIRS instruments at the Gemini North observatory. The collected spectra were combined into an atlas of heliocentric vacuum wavelengths with a joint statistical and systematic accuracy of 0.1{AA} in the optical and 0.3{AA} in the near-infrared. The wavelength atlas and the related 1D and 2D spectra are made publicly available.