There are two fits files for each band for each epoch (24 files), one that shows the earliest possible observation time, and one that shows the latest possible observation time. The fits image units are "Minutes past Julian Date 2453400.5" as stated in the fits header. The fits files are 2" pixels. The files are: Epoch0 (S3MC) SAGE_SMC_IRAC3.6_E0.earliest_obstime.fits SAGE_SMC_IRAC3.6_E0.latest_obstime.fits SAGE_SMC_IRAC4.5_E0.earliest_obstime.fits SAGE_SMC_IRAC4.5_E0.latest_obstime.fits SAGE_SMC_IRAC5.8_E0.earliest_obstime.fits SAGE_SMC_IRAC5.8_E0.latest_obstime.fits SAGE_SMC_IRAC8.0_E0.earliest_obstime.fits SAGE_SMC_IRAC8.0_E0.latest_obstime.fits The region files for each are: SAGE_SMC_IRAC3.6_E0.reg SAGE_SMC_IRAC4.5_E0.reg SAGE_SMC_IRAC5.8_E0.reg SAGE_SMC_IRAC8.0_E0.reg Epoch 1 SAGE_SMC_IRAC3.6_E1.earliest_obstime.fits SAGE_SMC_IRAC3.6_E1.latest_obstime.fits SAGE_SMC_IRAC4.5_E1.earliest_obstime.fits SAGE_SMC_IRAC4.5_E1.latest_obstime.fits SAGE_SMC_IRAC5.8_E1.earliest_obstime.fits SAGE_SMC_IRAC5.8_E1.latest_obstime.fits SAGE_SMC_IRAC8.0_E1.earliest_obstime.fits SAGE_SMC_IRAC8.0_E1.latest_obstime.fits The region files for each are: SAGE_SMC_IRAC3.6_E1.reg SAGE_SMC_IRAC4.5_E1.reg SAGE_SMC_IRAC5.8_E1.reg SAGE_SMC_IRAC8.0_E1.reg Epoch 2 SAGE_SMC_IRAC3.6_E2.earliest_obstime.fits SAGE_SMC_IRAC3.6_E2.latest_obstime.fits SAGE_SMC_IRAC4.5_E2.earliest_obstime.fits SAGE_SMC_IRAC4.5_E2.latest_obstime.fits SAGE_SMC_IRAC5.8_E2.earliest_obstime.fits SAGE_SMC_IRAC5.8_E2.latest_obstime.fits SAGE_SMC_IRAC8.0_E2.earliest_obstime.fits SAGE_SMC_IRAC8.0_E2.latest_obstime.fits The region files for each are: SAGE_SMC_IRAC3.6_E2.reg SAGE_SMC_IRAC4.5_E2.reg SAGE_SMC_IRAC5.8_E2.reg SAGE_SMC_IRAC8.0_E2.reg ============================================================================= Brian has written an IDL program get_smc_jd.pro which given an input RA & Dec, and the appropriate timestamp fits file, outputs the earliest (or latest) MJD. It will take either a single position or an array of positions. There are examples of usage in the IDL program. The baseline Julian Date offset is 2453400.5