Abstract
To accomplish its mission, the spaceborne observatory SNAP (SuperNova Accel- eration Probe) requires a pointing stability of < 0.03 arcseconds during exposures lasting up to 500 seconds. A Monte Carlo simulation of the photoelectron statistics from the guiding star investigates geometrical (such as the pixel size of the detector or the plate scale) and physical parameters (such as the magnitude of the star). It is shown that simple centroiding calculations can lead to the desired accuracy with guide stars as faint as magnitude 16. Availability of these stars is verified thanks to the HST Guide Star Catalog complemented with a statistical model of the distribution of stars. Thus a through-the-lens sensor that uses stars as faint as magnitude 16 to provide the necessary guiding signals is feasible. In one year of study, the SNAP (SuperNova Acceleration Probe) satellite can discover, follow the light curve, and obtain spectra at peak brightness for more than 2000 supernovae. SNAP instrumentation includes a wide field optical imager (field of view of one square degree) and a small IR imager, which, combined with filters, will allow photometry from 0.35 to 1.7 µm and a three arm spectrograph sensitive in the same range of wavelengths. SNAP instrumentation will be used with a simple, predetermined observing strategy designed to monitor a 20 square degree region of sky both near the north ecliptic pole (16 h 25 min + 57 deg) and near the south ecliptic pole (4 h 30 min 52 deg), discovering and following supernovae that explode in these regions. More information on the scientific background of this mission can be found at the URL http://snap.lbl.gov. The data from the wide field optical imager will serve both as search images and for follow-up photometry. The detection of supernovae is ac- complished by a repeated comparison of fixed fields to reference images. The optical photometer obtains wide-field frames overlapping the positions of
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
