I spoke with Thom this morning about what path he is taking with the reference files. I believe he is using each mast pipeline .drz image to do the photometry on the .flc images that are in the frame of that reference image. I am interested to see how this works. I am personally still not sure what the best way to proceed on reference images is. I am even confused about what the reference image does. My current understanding is that it provides the coordinate system over which to overlay dolphot’s photometry. I am confused about the necessity of it though, since the flt images have accurate wcs data. The enhanced resolution of drz images would enhance the source positional accuracy, so perhaps that is why we use dr(z/c) images as references.

To cover my bases, I am taking the time now to download comprehensive flc, flt, drc, and drz files from MAST of the NGC6819. I am unsure whether some of my errors (such as the free point not allocated error) may come from using flc and drc instead of flt and drz. While the flc and drc are more accurate data since they account for CTE corrections, much of the documentation around dolphot mentions flt and drz. Although I assumed they were interchangeable terms since accounting CTE correcting seems like it would be minimally invasive, I am not going to count on it, and I am downloading everything. These downloads are going to take nearly all day.

Upon further thought, drc and drz images should both be equally good at functioning as reference images, since sources will appear in the same place even if the noise is different.

Next Few Days Schedule

Tomorrow I head down to New Hampshire, but I will have a few hours to work in the morning. I hope to make more progress then. After tomorrow, I will have a few days off the grid and I hope to be back here on Thursday to continue.