4.4 Missing Minor Frame Detection

Missing minor frames (MMFs) or ``data dropouts'' are flagged and recorded in the $\nu$ flag image, as well as noted in the output core data item keyword ABNMINFR. A minor frame consists of 96 consecutive pixel values read down in batch from the satellite. Minor frames are used to reconstruct the image, beginning at line 1, sample 1 by assigning values for incremental samples. Occasionally, one or more minor frames are corrupted or missing from the telemetry stream resulting in consecutive values of zero in the image. Such missing minor frames are detected automatically in the NEWSIPS system by screening the data for 96 consecutive values of zero. Only the target region is screened for missing minor frames; therefore, any MMFs outside the target area will not be detected or flagged. These 96 pixels are then flagged with a $\nu$ flag value of -8192. No attempt is made to interpolate across or correct for such data loss. A more detailed description of the IUE telemetry system can be found in IUE Technical Note No. 30.