ISSA Explanatory Supplement
APPENDIX C
Pre-Production Anomalies
Prior to production, a list of anomalies to be removed from the ISSA was assembled from three sources. The list was a composite of the anomalies found in calibration and pointing reconstruction, in the SkyFlux image product, and in the IRAS Faint Source Survey.
Not all anomalies in the SkyFlux images were placed on the list. Only particle hits (p) and radiation hits (r) were removed. Other anomaly types from the SkyFlux image product were thought to be salvageable using the calibration and destriping techniques employed in making the IRAS Sky Survey Atlas.
The following table summarizes the composite list of anomalies. The anomaly type is given along with the number of seconds removed or number of complete scans removed. An explanation of the anomaly type code is also included. A total of 42 or 0.7% of total number of scans were removed due to calibration problems along with 32,288 seconds or approximately 0.3% of the entire mission due to other problems.
| Source of Anomaly Identification |
Type | # scans removed |
# seconds removed |
|---|---|---|---|
| Calibration and Pointing Reconstruction |
lg t bb xs re | 25 7 10 |
123 52 |
| Original Image Anomalous Scans |
p r | 13,735 3,170 | |
| Faint Source Survey | 15,208 | ||
| SUBTOTAL | 42 ~ 0.7% | 32,288 ~ 0.3% | |
| TOTAL | 42 ~1% | ||
| lg = | low-gain ao/survey |
| t = | survey following TFCAL (see §III.A.2.b) (not recommended due to bias boost) |
| bb = | bias boost problem |
| xs = | cross-scan excursions (pointing) |
| re = | roll excursions (pointing) |
| p = | particle hits |
| r = | radiation hits |