A New 100-GHz Band Front-End System with a Waveguide-Type Dual-Polarization Sideband-Separating SIS Receiver for the NRO 45-m Radio Telescope

We developed a waveguide-type dual-polarization sideband-separating SIS receiver system of the 100-GHz band for the 45-m radio telescope at the Nobeyama Radio Observatory, Japan. This receiver is composed of an ortho-mode transducer and two sideband-separating SIS mixers, which are both based on the waveguide technique. The receiver has four intermediate frequency bands of 4.0--8.0 GHz. Over the radio frequency range of 80--120 GHz, the single-sideband receiver noise temperatures are 50--100 K and the image rejection ratios are greater than 10 dB. We developed new matching optics for the telescope beam as well as new IF chains for the four IF signals. The new receiver system was installed in the telescope, and we successfully observed the 12CO, 13CO and C18O emission lines simultaneously toward the Sagittarius B2 region to confirm the performance of the receiver system. The SSB noise temperature of the system, including the atmosphere, became approximately half of that of the previous receiver system. The Image Rejection Ratios (IRRs) of the two 2SB mixers were calculated from the 12CO and HCO+ spectra from the W51 giant molecular cloud, resulting in > 20 dB for one polarization and > 12 dB for the other polarization.Comment: 10 pages, 13 figures, Accepted for publication in PASJ, version with high resolution figures is available via http://www.nro.nao.ac.jp/library/report/list.htm

ASTE CO(3-2) Observations of the Barred Spiral Galaxy M 83: I. Correlation between CO(3-2)/CO(1-0) Ratios and Star Formation Efficiencies

We present CO(J=3-2) emission observations with the Atacama Submillimeter Telescope Experiment (ASTE) toward the 5' x 5' (or 6.6 x 6.6 kpc at the distance D = 4.5 Mpc) region of the nearby barred spiral galaxy M 83. We successfully resolved the major structures, i.e., the nuclear starburst region, bar, and inner spiral arms in CO(J=3-2) emission at a resolution of 22'' (or 480 pc), showing a good spatial coincidence between CO(J=3-2) and 6 cm continuum emissions. We found a global CO(J=3-2) luminosity L'_CO(3-2) of 5.1 x 10^8 K km s^-1 pc^2 within the observed region. We also found L'_CO(3-2) in the disk region (0.5 < r < 3.5 kpc) of 4.2 x 10^8 K km s^-1 pc^2, indicating that CO(J=3-2) emission in the disk region significantly contributes to the global L'_CO(3-2). From a comparison of a CO(J=3-2) data with CO(J=1-0) intensities measured with Nobeyama 45-m telescope, we found that the radial profile of CO(J=3-2)/CO(J=1-0) integrated intensity ratio R_3-2/1-0 is almost unity in the central region (r < 0.25 kpc), whereas it drops to a constant value, 0.6--0.7, in the disk region. The radial profile of star formation efficiencies (SFEs), determined from 6 cm radio continuum and CO(J=1-0) emission, shows the same trend as that of R_3-2/1-0. At the bar-end (r ~ 2.4 kpc), the amounts of molecular gas and the massive stars are enhanced when compared with other disk regions, whereas there is no excess of R_3-2/1-0 and SFE in that region. This means that a simple summation of the star forming regions at the bar-end and the disk cannot reproduce the nuclear starburst of M 83, implying that the spatial variation of the dense gas fraction traced by R_3-2/1-0 governs the spatial variation of SFE in M 83.Comment: 13 pages, 11 figures, PASJ in press, version with high resolution figures is available via http://www.nro.nao.ac.jp/~z5001km/m83-aste.pd

Assignment of CPS1, OTC, CRYD2, ARG2 and ASS genes to the chicken RH map

An attempt was made to assign five genes, CPS1, OTC, ASS, CRYD2, and ARG2, to chicken chromosomes (GGA) by radiation-hybrid mapping. OTC was assigned to GGA1; ARG2 to GGA5; CPS1 to GGA7; and CRYD2 to GGA19. ASS was not, however, assigned to a specific chromosomal position