H.Bushouse, J.MacKenty, C.Skinner
STScI
E.Stobie
U.Arizona
The Hubble Space Telescope second-generation instruments offer new challenges to the pipeline systems that will be used to process the data they produce. This is due in large part to the production of multiple, contemporaneous images for a single observation of a target. For the Near Infrared Camera and Multi-Object Spectrometer (NICMOS), contemporaneous observations will mainly result from the use of two particular observing strategies: 1) measurement of the infrared background from regions of the sky adjacent to the target; and 2) ``mosaicing'' of images of large angular-sized targets. The NICMOS calibration pipelines that are being developed and implemented at the Space Telescope Science Institute (STScI) and at the University of Arizona Steward Observatory by the NICMOS Investigation Definition Team (IDT) will utilize the concept of ``associations'' of images, which will allow the multiple images that constitute either a series of target and background observations or a mosaic pattern to be processed collectively as a set. The processing is divided into two distinct phases. The first phase treats each image in an association individually and performs the routine work of instrumental calibration, such as dark-current subtraction and flat fielding. The second phase proceeds once all the images in the association have completed phase 1 and treats the calibrated images collectively, performing the operations of background measurement and removal, as well as combining or mosaicing the calibrated images into a single final image of the target. This paper describes the concept of ``associated'' observations as utilized in the STScI proposal, observing, and data processing systems, as well as the software methodologies employed in the data processing pipelines.