Re: SETI public: Interesting Radio Observations of Gamma Ray Burst

• Previous message: Greg Preston: "SETI public: Interesting Radio Observations of Gamma Ray Burst"
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NA5N wrote:

> If you look at the above link, "signal strengths" of the radio energy is
> measured by scientists by "flux density," using units of mJy ... milli
> Jansky's. For example, current VLA detected flux density of this event
> is about 100 mJy at L-band (1 GHz) and 30 mJy at C-band (8 GHz).
> 1 Jy (1 Jansky) = 1.7 x 10EE-23 mW.
> 1 mJy = 1.7 x 10EE-26 mW.
>

That's actually a bit misleading, because Jansky is a measure of flux
density, NOT of power. Flux density is power per unit bandwidth over
capture area, so the calculation includes receive antenna size, and
receiver IF filter bandwidth. One Jansky is 10^-26 Joules per second
per hertz per square meter. See my article "understanding the Jansky"
<http://www.setileague.org/askdr/jansky.htm> for an elaboration. Or,
for a memory aid to assist in remembering the constant, see the last
verse of my song "Karl Jansky," at
<http://www.setileague.org/songbook/jansky.htm>.

> Figure out what the dBm is of that. Now THAT is QRP!

No doubt about it, that IS qrp (weak signal), at any receiver bandwidth
and any antenna capture area!
        73, Paul N6TX

-- 
H. Paul Shuch, Ph.D.    Executive Director, The SETI League, Inc.
433 Liberty Street, PO Box 555, Little Ferry NJ 07643 USA
voice (201) 641-1770;  fax (201) 641-1771; URL http://www.setileague.org
email work: n6tx_at_setileague.org;  home: drseti_at_cal.berkeley.edu
"We Know We're Not Alone!"

• Previous message: Greg Preston: "SETI public: Interesting Radio Observations of Gamma Ray Burst"
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