The following document lists the file abstract/BARR_AGN_BARR_VAR.abs
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SCIENTIFIC ABSTRACT We propose to study the mid- and far-IR variability in BL Lac objects already known to vary in the IRAS bands. The light curves will be sampled on timescales of seconds to hours, days , weeks and months with PHT multiband photometry. The raefets are 3C371 and OJ287. Our goals are; - to search for evidence of relativistic bulk motions through the observation of any large-amplitude, short-term variability; - to study the characteristic nature of the IR light curves; - flares, flickering, possible coherent signals; - to study any variation on the IR continuum spectrum and look for between different wavebands, as possible diagnostics for inhomogeneous jet models OBSERVATION SUMMARY 3C371 to be observed repeatedly with the following concatenated chain; Photometry with PHT03 at 11.5 and 25 Microns, followed by photometry with PHT22 at 60 and 160 microns, followed by PHT03 at 11.5 microns to check for any very rapid variability. Times include rectangular chopping and aim for a signal-to-noise ratio of at least 10. OJ287 would be studied in a single uninterupted observation consisting of a (long!) concatenated chain. The observing time for OJ287 is determined, not by any required signal-to-nosie ratio, but by the desire to observe for long enough to characterise the light curve. The strategy is to cycle through three filters, 25, 70 and 170 microns, concatenating AOTs PHT03 and PHT22 and observing for the maximum 2048s in each filter, including recaangular chopping. This cycle is performed four times in a single pointing, so at each wavelength approximately 35min of uninterrupted coverage is obtained, four times, separated by 100 minutes. For the case of a spring launch, one observation of OJ 287 and 16 repeated observations of 3C371 would be performed. OJ 287 is unobservable in the case of an Autumn launch; therefore, all time would be dedicated to 3C371, with 16 observations (concatenated chains) as priority 1 and a further 9 as priority 2.