Local HI: Constraints on the evolution of the HI content of the Universe

Analyses of QSO absorption lines are showing that HI content has evolved over the redshift range z=5 to z= 0. The 21cm line measurements of the z=0 HI content avoid several biases inherent in the absorption line technique, such as the influence of evolving dust content in the absorbers, and will produce a reliable measure to anchor theories of galaxy evolution. Examples of important questions to be addressed by local HI surveys are: (1) is there a significant population of gas-rich galaxies or intergalactic clouds that are missing from the census of optically selected galaxies? (2) is there an adequate reservoir of neutral gas to substantially prolong star formation at its present rate? and (3) are there massive objects of such low HI column density that they can have escaped detection in the ``unbiased'' HI surveys that have been conducted so far?Comment: 8 pages; Latex; 2 encapsulated postscript figures. Presented at the workshop `HI in the Local Universe', Sydney, May 13-15 1996. Accepted for publication by Publications of the Astronomical Society of Australia. Also available from http://www.atnf.csiro.au/Publications/HI_workshop/proceedings.htm

Radio observations of Titan

Saturn and Titan have been observed at three frequencies (1420, 2695, and 8085 MHz) with the NRAO interferometer. A clear positive Titan detection has been obtained at 8085 MHz. Assuming Titan's radius is 2500 km, the radio brightness temperature (i.e. for unit emissivity) is 115 + or - 35 K

Moon - Optical properties of Apollo 11 samples

Optical properties of lunar powder samples from Tranquility Bas

HI 21cm observations of the PG1216+069 sub-DLy-alpha absorber field at z=0.00632

The Westerbork Synthesis Radio Telescope finds a weak 21cm line emission feature at the coordinates (RA-Dec-velocity) of the sub-Damped Lyman-alpha absorber observed at z_abs=0.00632 in the spectrum of PG1216+069. The emission feature, WSRT-J121921+0639, lies within 30" of the quasar sightline, is detected at 99.8% (3 sigma) confidence level, has M_HI between 5 and 15x10^6 M_solar, and has velocity spread between 20 and 60 km/s. Other HI emitters in the field include VCC297 at a projected distance of 86/h_75 kpc and a previously unreported HI cloud, WSRT-J121919+0624 at 112/h_75 kpc with M_HI ~ 3x10^8 M_solar. The optically identified, foreground galaxy that is closest to the quasar sightline appears to be VCC339 (~L*/25) at 29/h_75 kpc and velocity offset 292 km/s . A low surface brightness galaxy with the HI mass of the sub-DLA absorber WSRT-J121921+0639 would likely have m_B ~ 17, and its diffuse optical emission would need to compete with the light of both the background QSO and a brighter foreground star ~10" from the QSO sight line.Comment: 10 pages, 2 figures, accepted for publication in ApJLet