MicroCosm® Year 2000 Readiness
Beginning with Version 2011.00, all of the MicroCosm® programs now measure time as 32-bit integral minutes and 64-bit floating point seconds elapsed since January 6.0, 1941 [JD 2430000.5]. The integral portion of this time will remain valid until January 30.0, 6024 [JD 3921308.5]. Two new input observation data formats have been defined: 1) PVK Data Format has been developed as a modernization of the PCE Data Format and uses four-digit years when defining dates; 2) MicroCosm® Character Data Format has been developed as a modernization of both the GEOS-C Data Format and the GEOS-C 120 Byte Extended Format and uses four-digit years when defining dates. Version 2 of the MicroCosm® Binary Metric Tracking Format has been defined and now represents times as 32-bit integral minutes and 64-bit floating point seconds elapsed since January 6.0, 1941 [JD 2430000.5]. Times defined in the original version of the data format would have begun to overflow beginning on January 18, 2036 [JD 2464710.5]. Version 2 times will not begin to overflow until January 30, 6024 [JD 3921308.5]. Version 2 of the MicroCosm® Attitude Quaternion File Format has been defined and now represents times as 32-bit integral minutes and 64-bit floating point seconds elapsed since January 6.0, 1941 [JD 2430000.5]. Times defined in the original version of the data format would have begun to overflow beginning on January 18, 2036 [JD 2464710.5]. Version 2 times will not begin to overflow until January 30, 6024 [JD 3921308.5]. A new optional environment varibale (MicroCosm_CALENDAR_YEAR1) has been defined to allow MicroCosm® programs to continue to utilize two-digit year inputs. The MicroCosm_CALENDAR_YEAR1 environment variable allows users to define the beginning of a 100 year window over which the two-digit year inputs will be valid. By default, if this variable is not defined, it will be assumed to take on the value 1957. For example, if this variable is defined as 1980, then values of 80-99 will be treated as being in the 20th century and values 00-79 will be considered to be in the 21st century. This will allow the continued utilization of data in the GEOS-C formats as well as data in the PCE format. Furthermore, existing setup files for MicroCosm® Control will remain fully compatible. A new keyword option (YEAR1) for MicroCosm® Control will also be available to override the MicroCosm_CALENDAR_YEAR1 environment variable. MicroCosm® TDF may override the MicroCosm_CALENDAR_YEAR1 environment variable for each individual input observation data file. With these improvements, the MicroCosm® Software Version 2011.00 iand later versions are now fully functional through the year 2200. The year 2200 limitation is imposed by the availability of precise JPL Lunar and Planetary Ephemeris only through year 2200. Back to MicroCosm®
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