Discovery of planetary nebulae using predictive mid-infrared diagnostics

Accepted. Received; in original form We demonstrate a newly developed mid-infrared (MIR) planetary nebula (PN) selec-tion technique. It is designed to enable efficient searches for obscured, previously un-known, PN candidates present in the photometric source catalogues of Galactic plane MIR sky surveys. Such selection is now possible via new, sensitive, high-to-medium res-olution, MIR satellite surveys such as those from the Spitzer Space Telescope and the all-sky Wide-Field Infrared Survey Explorer (WISE) satellite missions. MIR selection is based on how different colour-colour planes isolate zones (sometimes overlapping) that are predominately occupied by different astrophysical object types. These tech-niques depend on the reliability of the available MIR source photometry. In this pilot study we concentrate on MIR point source detections and show that it is dangerous to take the MIR GLIMPSE (Galactic Legacy Infrared Mid-Plane Survey Extraordi-naire) photometry from Spitzer for each candidate at face value without examining the actual MIR image data. About half of our selected sources are spurious detection