Eintrag weiter verarbeiten
Small‐comet “atmospheric holes” are instrument noise
Gespeichert in:
| Zeitschriftentitel: | Geophysical Research Letters |
|---|---|
| Personen und Körperschaften: | , , , |
| In: | Geophysical Research Letters, 25, 1998, 19, S. 3713-3716 |
| Format: | E-Article |
| Sprache: | Englisch |
| veröffentlicht: |
American Geophysical Union (AGU)
|
| Schlagwörter: |
| Zusammenfassung: | <jats:p>Frank and Sigwarth claim that dark pixel clusters observed by the VIS Earth Camera are atmospheric holes created by small comets. We have examined their catalog, which contains about 700,000 of these “atmospheric holes”, for consistency with this small‐comet hypothesis and with instrument noise. A geometrical requirement of the small‐comet hypothesis is that the number of pixels in a typical cluster must vary by a factor > 100 with spacecraft altitude because of the inverse‐square law of the apparent cluster area versus distance. We find no systematic variation of duster size with spacecraft altitude. The Iowa catalog data are consistent with instrument noise because neither the size distribution nor the event rate of dark pixel clusters depend on altitude. At altitudes outside of the radiation belts during the one day of available raw data, more than 75% of the dark pixel dusters result from the process that Frank and Sigwarth employ to remove bright pixels caused by energetic particles. This data processing also causes additional meaningless dark pixel clusters to occur in the dark sky or over the dark Earth.</jats:p> |
|---|---|
| Umfang: | 3713-3716 |
| ISSN: |
0094-8276
1944-8007 |
| DOI: | 10.1029/98gl02572 |