Near IR observations of the Arecibo sample of OH/IR stars

We have obtained near IR J, H and K images of the full Arecibo sample of OH/IR stars 350 sources) at the Calar Alto 1.23m telescope equipped with MAGIC. These data will be used to identify first the near IR counterparts and then the sources optically on the POSS plates, whenever possible, and to improve their coordinates. About 70% of the observations were made under photometric conditions, which permits us to combine the near IR with the IRAS fluxes and to study the spectral energy distribution for a great part of the sample. One focus is the identification of PPNe in a region of the IRAS color-color diagram which is populated mostly by variable OH/IR stars. At the present time approximately 75% of the observations have been reduced. Due to their unusual colors in the near IR we propose three new PPNe candidates.