Generates MESSENGER SPKs from the output of kerneldbgen and the NAIF utility
commnt.
This program was created to help automate the process of generating new
SPK DB files for the MESSENGER mission, as the output from the ISIS
program kerneldbgen requires some further tweaking in order to be fully
accurate. Specifically, it sets the end date of the reconstructed time
period far into the future, which should be moved into a separate
predicted section.
This program creates the predicted section. In order to determine the
proper end time for the reconstructed range (and start time for the
predicted range), a NAIF utilitt known as commnt is used (available as
part of ISIS). Prior to running this program, the user should run commnt
as shown in the following example:
commnt -r msgr_20040803_20120401_od233sc_0.bsp
Here, replace the argument with whatever the most recent BSP file happens
to be. This will, however, dump far more information than this program is
actually interested in. To get the relevant end time, pipe the output of
commnt into the following:
grep -A 1 "Orbit" | sed -n "2p"
An example of all this can be found in the downloadMessengerKernels
script.
This program will typically be run automatically, and update the most
recent DB file (generated by kerneldbgen) in place. The user optionally
specify any UTC time or any output file, not conforming to the process
laid out above.
