I wanted to insert synthetic moving objects in HSC images with a catalog containing visit number, filters and magnitudes of a given object. I noticed that there is no option to just insert only star like objects. The default code requires that the catalog specify galaxy specific information (such as ellipticity, size, etc) which is odd. There is also no facility to input a given object into a particular visit.

This improvement will 

1) add an option, `insertOnlyStars` which will not require extraneous information to be passed in the fake object catalog.

2) add an option which allows the user to inject objects belonging to a particular visit.

3) Also deal with an issue where the fakes were not inserted at the edge CCDs of a field of view, as the pixscale on those CCDs was checked at the center of the FOV rather than the center of the CCD itself. Because the jointcal WCS has a reference at the center of the visit, this caused some fake insertions to not work correctly.

I have a working branch for this code built on top of a recent weekly build. So if this sounds like something interesting to be added, this functionality can be added to the pipeline.