[vsnet-chat 2621] Re: Tmz85

[aah@nofs.navy.mil]

Kato-san has raised a good point.  If, for a faint source,
  (a) all data is collected with the same telescope/camera/filter
  (b) no intrinsic shape variations change the light curve shape
        from one cycle to the next
  (c) no systematic errors are present in your magnitude extractions
then you can take short exposures, phase your data, and smooth
the data to improve the signal/noise in the mean light curve.  This
is the same technique used by observers in the photographic era to
obtain mean light curves of short-period variable stars, or in the
photoelectric era to obtain the mean light curve of the Crab Pulsar.
  However, keep the three restrictions in mind.  I won't go into
the statistical reasons, but even accepted psf programs like DAOPHOT
have systematic errors at low signal/noise or bright sky background.
Arne

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