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Re: more details of signal-to-noise calculations for Mark IV
- To: Chris Albertson <email@example.com>
- Subject: Re: more details of signal-to-noise calculations for Mark IV
- From: Stupendous Man <firstname.lastname@example.org>
- Date: Thu, 29 Oct 1998 09:27:47 -0500
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- Delivery-Date: Thu Oct 29 09:28:46 1998
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> I'm still reading Michael's message but I don't see where he
> assumes we are pointing. Is it to zenith (airmass = 1.0)
> or down at the equator?
> Is atmospheric extinction built into the "photons from a mag
> zero star" constant?
Good point. The calculation assumes that one is looking at a
star _above_ the atmosphere, at an airmass of zero. The extinction
due to ordinary air is
20% in the V-band at zenith 30% in V-band at 45 degrees over
8% in the I-band 11% in I-band at 45 degrees over
So the numbers in my previous tables are slight overestimates of
the expected signal-to-noise.
Michael Richmond "This is the heart that broke my finger."