CVZ Monitoring

Monitoring the subscription of the CVZ is important. An example of how neglect can contribute to the long delay of programs is 7410. This CVZ program took over 2 years to complete, but could have taken 1 or 2 years longer had subscription problems & competition with other CVZs not been clearly identified.

How filled the CVZs are can be determined by running the unix tool cvz-targs .

unixprompt> cvz-targs

Print the resulting plot from ghostview.

This produces an IDL plot file showing the distribution of CVZ est_orbits as a function of RA for northern CVZ targets plus RA+180-degrees for southern targets. The reason that southern targets are shifted halfway around the sky in this plot is that they compete for CVZ time with northern targets which are at RAs 180 degrees away.

Bin sizes in this plot are a half-day in size (HST sidereal precession cycle is 56 days, so there are 112 bins). Although this is a higher resolution than necessary, it shows the distribution very discretely. CVZ opportunities vary in length depending upon bright earth limb avoidances, target declination, and other factors, so some visits could have longer or shorter contiguous CVZ opportunities than others. This plot does not show how broad or narrow individual opportunities are nor how many integrated days or orbits per year are available for given targets. Closely spaced peaks can have CVZ opportunities that overlap, so the potential for interference between neighboring peaks exists.

Once the plots are produced, you should manually identify (with the tool's screen output) the proposals in each of the largetst peaks, load them in SPIKE and examine the PW distribution. If there are ways to smooth the distribution to help mitigate conflicts, move the plan windows, being mindful of the total subscription levels, in particular the SAA-free.