The IRAS point source catalogue

We have cross-correlated the IRAS point source catalogue [15] with the FBS. There are 10537 IRAS sources in the area of interest. We expect ten chance coincidences within 2$^\prime$ from the 1103 FBS objects and 2.5 within 1$^\prime$. We found 17 IRAS sources within 2$^\prime$ of the FBS objects. We have measured accurate optical positions for these objects (Table 1); two turned out to be more than 2$^\prime$ from the IRAS sources; one (FBS 1340+813), a white dwarf, is located near the bright K2 star SAO 2257 which is identified with the source IRAS 13407+8118 [8]. FBS 0432+763 is located near the M star SAO 5262 which is associated with the IRAS source. IRAS 04378+7532 is associated with the galaxy UGC 3130 rather than with FBS 0437+756. IRAS 16402+3611 is associated with the M star CLS 106 [52] rather than with FBS 1640+362. IRAS 17562+4412 coincides with an uncatalogued bright star and is therefore probably not associated with FBS 1756+441. These seven objects are certainly chance coincidences.

All the four FBS planetary nebulae are detected by IRAS, while none of the UV excess stars is. Five QSOs are also detected, i.e. only $\sim$14% of all known QSOs in the field. The position of FBS 1821+643 coincides with that of the nucleus of the planetary nebula PK 094+27.1 [4]; it is not the QSO KUV 18217+6419 which is located 84$^{\prime\prime}$ away. There is only one unclassified FBS object coinciding with an IR source, IRAS 11334+7523 which however is located 14$^{\prime\prime}$ away from a 16$^{\rm th}$ mag galaxy, a more likely identification.

The small fraction of all QSOs which are detected as IRAS sources make this survey of little use to check the completeness of the FBS.