Optical SETI Map Conferences Map Illustrations Map Photo Galleries Map Observations Map Constructing Map
Search Engines Contents Complete Site Map Tech. Support Map Order Equip. Map OSETI Network

Search WWW Search www.coseti.org Search www.oseti.net Search www.photonstar.org Search www.opticalseti.org

colorbar.gif (4491 bytes)


Optical Signal Visibility & Detectability




EIRP Distance Magnitude Bandwidth CNR
1 kW 2.3 x 1018 W 10 L.Y. +23 1 Hz 34 dB
1 MW 2.3 x 1021 W 10 L.Y. +15.5 10 kHz 24 dB
1 GW 2.3 x 1024 W 10 L.Y. +8 30 MHz 19 dB
1 GW 2.3 x 1024 W 10 L.Y. +8 4.6 GHz -3 dB

Wavelength = 656 nm, 10 meter diameter T/R telescopes.

1 Light Year (L.Y.) = 9.461 x 1015 m.

Eye sensitivity = 6th magnitude.

Planckian starlight at 2nd magnitude ignored.


A 1 GW transmitted signal is just below the threshold for naked eye visibility in very good seeing conditions. This received signal would be strong enough for high quality "real-time" FM modulated NTSC/PAL TV signals (30 MHz bandwidth). An incoherent filter with spectral resolution of 1 part in 100,000 would have a bandpass of 0.0066 nm, equivalent to an optical bandwidth of 4.6 GHz. In this situation, the recovered CNR would be -3 dB, and thus the signal would not be detectable without further post-detection signal integration. A high-resolution spectrometer/CCD system would detect this signal because such instrumentation integrates the received signal for a considerable period of time.

Home Glossary
SPIE's OSETI I Conference SPIE's OSETI II Conference
SPIE's OSETI III Conference
The Columbus Optical SETI Observatory
Copyright , 1990-2006 Personal Web Site:
Last modified:  10/28/06
Contact Info