Spitzer Space Telescope - General Observer Proposal #3644 Far Infrared Study of SN Ia Host Galaxies Principal Investigator: Lajos Balazs Institution: Konkoly Observatory of the Hungarian Academy of Sc Co-Investigators: Peter Meszaros, Pennsylvania State University Peter Abraham, Konkoly Observatory Attila Moor, Konkoly Observatory Csaba Kiss, Max-Planck-Institut fur Astronomie Science Category: intermediate-z galaxies 0.05 0.1 from the list of Tonry et al. (2003) and 10 more ones which were cross-identified with IRAS galaxies. We propose to get MIPS photometry from all targets at 24, 70 and 160 micron. The sample of the SN Ia hosts gives a unique opportunity to study the star formation activity and dust property as a function of the redshift. Although, the Ia type supernovae are not directly related to the star formation the anomalous dust properties have to be taken into account at their photometry. The SN Ia sample is biased towards objects of law extinction where the bulk of the dust is only in the background. However, the direction of the observer's line of sight is fully random and in a considerable fraction of cases the influence of the intrinsic dust extinction could be quite significant. The result might serve a useful input information for studying the proper conditions for optical afterglows of gamma ray bursts (GRB). There is a so far not fully understood dichotomy of the GRBs having or not optical after glow. A possible interpretation appears to be the absorption of the optical radiation in the interstellar dust. The suspected progenitors of these GRBs are the very massive stars strongly related to dense giant interstellar dust clouds. Normally, the observed GRBs are at higher z than the known Ia type SNs. However, the FIR results obtained for the SN Ia hosts might deliver a useful input information for planning FIR observations of GRB hosts. The observing time calculated for MIPS photomery amounts to 29.2 hours.