Instructions for Interpreting the Radio Astronomy Report

*** CloudSat radar operations have been discontinued and there is no longer a need to avoid astronomical observations during satellite overpasses. The instructions below and the Radio Astronomy Overpasses file no longer apply and will be removed from this website in the near future. ***

The CloudSat Radio Astronomy Report provides information on when the radio energy from CloudSat's Cloud Profiling Radar might cause a problem for radio astronomy sites. When CloudSat is actively taking data in its current operations mode, CloudSat aims the Cloud Profiling Radar points roughly four degrees to the left of nadir, with a variation around this pointing angle that ranges from positive to negative five degrees. Radio astronomy sites who wish to avoid receiving energy from the Cloud Profiling Radar will want to avoid observations when the footprint of the Cloud Profiling Radar passes over their ground location. This report provides the start and stop times for those periods of time for each of the sites analyzed. 

The report consists of six main columns of data: the site, the Rise Time in UTC, the Set Time in UTC, the Duration of the overflight, and a boolean flag indicating whether or not CloudSat is in the sun at the time of the overflight. 

- The Site is the name of the radio astronomy site affected by the overflight
- The Rise Time gives the UTC time of the start of a potentially damaging overflight
- The Set Time gives the UTC time of the end of a potentially damaging overflight
- The Duration is the length, in seconds, of the overflight
- The first boolean flag indicates if CloudSat is in sun (1) or eclipse (0) at the *start* of the overflight
- The second boolean flag indicates if CloudSat is in sun (1) or eclipse (0) at the *end* of the overflight

At this time, CloudSat does not take science data during eclipse, so any overflight where both boolean flags are set to zero (0) poses no threat to radio astronomy sites. It is recommended that radio astronomy sites cease observations, or limit observations to elevation angles below 80 degrees above the horizon, between the start times and the end times listed in the report for their sites, if the boolean flags are set to "1" indicating that CloudSat is in the sun during the overflight. 

The report will be updated weekly on Mondays, and at any point following a CloudSat maneuver, as the report relies on an accurate projection of CloudSat's orbital position.