The connection between the Exposure Logsheet that each observer fills
out during the Phase II proposal process and the datasets and associations that the observer receives once the observations are executed can be better understood through some examples.
The science data file in the dataset will contain 13 imsets (corresponding to
the MULTIACCUM NSAMP=12 parameter plus the 0’th read), and some of the header keywords will be filled with the relevant information from the target and exposure logsheets of the Phase II (e.g., the keywords targname, ra_targ, dec_targ,....).
In this observation, eight datasets (one for each position of the pattern) and
one association will be created. The pipeline products will include the eight reduced datasets, one mosaic of the background-subtracted target, and one mosaic of the background.
The number of iterations is 3, implying that three datasets will be generated
from this exposure logsheet, plus an association table containing the three datasets. The collection of multiple iterations into an association is a new feature introduced by the NICMOS and STIS pipelines. In our specific example, the co-added image from the three iterations will be one of the products of the pipeline.