Open Access
Table 1.
Reasons for missing or unusable EIT images.
| Reason | Affected bands | Effect | Text reference |
|---|---|---|---|
| Near mission loss | All | No EIT images between 25 June and 12 October 1998 | 2.1 |
| High gain antenna failure | All | Data gaps (“keyhole” periods) of ∼2 weeks every ∼6 months between May 2003 and August 2009. We note these gaps overlap with CCD bakeout periods, occurring throughout the mission's lifetime. | 2.1 |
| CCD bakeouts | All | Data gaps of varying duration (∼a few days to ∼2 weeks) and frequency, often scheduled to coincide with keyholes. The combined keyhole-bakeout duty cycle is ≲15% of the mission baseline. Bakeouts also introduce discontinuities in the EIT light curves. | 2.1, 2.6.2 |
| Missing or corrupted data blocks | All | Some images have missing pixels. ∼9% of the total number of EIT images must be discarded. | 2.2 |
| Pinholes | 284 Å band to a significant extent; other bands negligibly | Before May 1998, a significant number of 284 Å images, and a handful of images in the other bands, have bright spots due to pinholes in EIT's front heat-rejection filter. 5.6% of the total number of 284 Å images must be discarded, and there is no 284 Å data between August 1996 and May 1998. | 2.5 |
| Solar proton events | All | ∼5% of all images appear “staticky” and must be discarded. | 2.5 |
| Other one-off camera errors | All | <0.1% of all images must be discarded due to random problems (blurriness, underexposure, overexposure, etc.). | 2.5 |
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