Abstract
A complete sample of PPN candidates was selected mainly based on the IRAS colors(Hu et al.,1990). For total 62 unknown objects in the sample we have made 1. ground-based infrared astrometry; 2. optical identifications; 3. near infrared and optical photometry; 4. optical spectroscopic observations; 5. radio molecular line observations(OH maser and CO thermal lines); and 6. check the optical variations from historical plates. Some additional observations such as high resolution spectraoscopic, optical/NIR CCD imaging observations for particularly interested objects were also carried out.
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