Re: (IAAC) [amastro] Re: limiting magnitude at WSP

Lew Gramer wrote:
> Alex Langoussis writes:
> >Your mileage may vary.  When comparing skies at different observing
> >sites, I would think the best results would be obtained by  the same
> >observers using the same scopes at the different sites.
> This is key, Alex: using unaided-eye Limiting Magnitude as an analog, two
> observers on the same night at the same location, with the same full (40+ min)
> dark adaptation, can differ in their LM as much as a full magnitude.
> And in fact, for the same INSTRUMENT and conditions, I'd be interested to hear
> what relationship holds between unaided and telescopic LMs across a sample of
> several different observers. With all-important individual variations accounted
> for, I suspect these two numbers are pretty well linked.
> BTW there is one problem with the sorts of charts published in S&T, and in the
> excellent guidebooks of some of our 'amastro' participants: unintentional bias.
> Particularly with estimates using intermittent averted vision, there seems to be
> a tendency for HONEST and EXPERIENCED observers to "see" what they know is
> there, even if strictly speaking it is not really visible.
> To completely avoid this, you have to sample multiple preselected, well-defined
> star fields in a session, and to do "double-blind" estimates: either plotting of
> the field without prior knowledge, or simply counting stars in the field.
> Lew Gramer
I couldn't agree more.  When a human being is the subject of an experiment,
utilizing a double blind design is often of vital importance.
Dave Mitsky
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