The FUSE Archival Data Handbook - MAST - STScI

Chapter 5
Ancillary Files
This section describes additional data files available from the FUSE archive that can be used
to support the analysis and understanding of FUSE data. Some of these data files were used
by CalFUSE to produce the calibrated data products, and others contain information which
can be used to verify the pointing, performance, or status of the satellite or instrument during
data acquisition.
This chapter contains information potentially useful to the “Advanced” and “Intermediate”
users. However its contents are not of immediate relevance to the “Casual” user. The file
naming convention used throughout this chapter has been described in Section 4.1.2.
5.1 FES Image Files (*fesfraw.fit, *fesfcal.fit)
Two nearly identical Fine Error Sensor (FES) cameras were available on FUSE. FES A was
prime for most of the mission, and observed the LiF1A FPA. FES B became prime on 12 July
2005 and was used for the remainder of the mission. It observed the LiF2A FPA. Because the
two cameras are on opposite sides of the instrument, the astronomical orientation in the images
will appear flipped with respect to each other. Referring to the guide star plots for a given
observation will provide confirmation of the expected astronomical orientation and star field
expected for a given target (see Section 5.6 below).
An image from the active FES camera was routinely acquired at the end of an observation
to allow verification of the pointing of the spacecraft. Depending on the phase 2 observing
proposal instructions provided by the user, this FES image would be obtained either with the
target in the observing aperture or at the reference point (55.18 ′′ from the HIRS aperture,
displaced towards the center of the FES field of view; see Fig. 2.2). By convention, this exposure
always has exposure ID 701, which is used to distinguish this image from acquisition images.
Other FES images were obtained throughout each observation during the initial guide star
acquisition and subsequent reacquisitions (usually after the target had been occulted). These
images are also stored and are available to the observer, although the target may be offset or
even absent in these images (e.g. if the target had drifted during occultation, etc.). These
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