18 Scorpii is located about 45.7 light-years (ly) from Sol. It lies at the northern edge of (16:15:37.3-8:22:10.0, ICRS 2000.0) of Constellation Scorpius, the Scorpion -- just off its left claw. The star can be found northwest of Zeta Ophiuchi, south of Yed Posterior (Epsilon Ophiuchi) and Yed Prior (Delta Ophiuchi), north of Graffias or Acrab (Beta1,2 Scorpii), and east of Zubeneschamali (Beta Librae). As 18 Scorpii has become one of the top 100 target stars for NASA's planned Terrestrial Planet Finder (TPF), images of this star and its position relative to the Milky Way in Earth's night sky are now available from the TPF-C team.

In late September 2003, astrobiologist Maggie Turnbull identified 18 Scorpii as one of the best candidates for hosting Earth-type life. The star was chosen from a shortlist of 30 stars (screened from the 5,000 or so stars that are estimated to be located within 100 ly of Earth) that were presented to a group of scientists from NASA's TPF and the ESA's Darwin planned groups of observatories (Astrobiology Magazine). The stars examined were selected from a larger list of 17,129 (of which 75 percent are located within around 450 ly, or 140 parsecs, of Sol) that were assembled into a Catalog of Nearby Habitable Stellar Systems (HabCat) by Turnbull and Jill Tarter of the SETI Institute (see: Margaret C. Turnbull, 2002, in pdf). Selection criteria for the 30-star shortlist included: X-ray luminosity, rotation, spectral types or color, kinematics, metallicity, and Strömgren photometry. On February 19, 2006, Turnbull named 18 Scorpii as a Sun-like star that is old enough to qualify as a top-five candidate for those listening for radio signals from intelligent civilizations (e.g., SETI Institute).

Searching on 2008-05-11 the following hit occurred.

Thumbnail of JPG

2008-05-11T00-36-36.WAV 13.7 Meg

Notes:

1. The JPG shows the results of reset as the receiver chirped
2. Running at full resolution and chirping so the lines appear to have Doppler
3. The system recorded from the time of the hit until 5:20 AM with no further carriers
4. The JPG shows that there are 5 files spaced by 60 Hz, each one lower amplitude than the last
5. The fact that the first like appeared at 60 Hz makes me think I am seeing some sort of power line noise
6. Full details of the observation are contained in the SML inside either the WAV or the JPG files