Hubble Space Telescope How can I maximize SNR when observing a faint diffuse target in the UV with the SBC?
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* Are there any special things I should consider if I'm worried about
getting enough signal-to-noise when observing a faint diffuse target
in the ultra-violet with the SBC ?
Remember, the SBC is a flight spare for the STIS MAMA; and similar
considerations may apply. The MAMA pixel size is very small projected
on the sky (0.03 arcseconds per pixel).
Therefore, the counts per pixel per second may be very low for a
diffuse source. However, the MAMA has no read noise and
the per pixel detector plus sky background in the ultraviolet is very
small. Thus you may be able to gain substantially on the
signal-to-noise ratio you achieve in a given integration time if do
not need the very high spatial resolution provided by the SBC,
simply by planning to integrate the data over multiple spatial
pixels on the ground. Also, be sure to use the broadest filter
that excludes the bright geocoronal Lyalpha line and the
OI airglow at 1300 Angstrom (F140LP).
The approx 10x fainter OI airglow at 1300 Angstrom may dominate
the background noise even for F125LP.