Nobeyama 45 m mapping observations toward the nearby molecular clouds OrionA, Aquila Rift, and M17: Project overview

We carried out mapping observations toward three nearby molecular clouds, Orion A, Aquila Rift, and M 17, using a new 100 GHz receiver, FOREST, on the Nobeyama 45 m telescope. We describe the details of the data obtained such as intensity calibration, data sensitivity, angular resolution, and velocity resolution. Each target contains at least one high-mass star-forming region. The target molecular lines were (CO)-C-12 (J = 1-0), (CO)-C-13 (J = 1-0), (CO)-O-18 (J = 1-0), N2H+ (J = 1-0), and CCS (J(N) = 8(7)-7(6)), with which we covered the density range of 10(2) cm(-3) to 10(6) cm(-3) with an angular resolution of similar to 20 and a velocity resolution of similar to 0.1 kms(-1). Assuming the representative distances of 414 pc, 436 pc, and 2.1 kpc, the maps of Orion A, Aquila Rift, and M 17 cover most of the densest parts with areas of about 7 pc x 15 pc, 7 pc x 7 pc, and 36 pc x 18 pc, respectively. On the basis of the (CO)-C-13 column density distribution, the total molecular masses are derived to be 3.86 x 10(4) M-circle dot, 2.67 x 10(4) M-circle dot, and 8.1 x 10(5) M-circle dot for Orion A, Aquila Rift, and M 17, respectively. For all the clouds, the H-2 column density exceeds the theoretical threshold for high-mass star formation of greater than or similar to 1 gcm(-2) only toward the regions which contain current high-mass star-forming sites. For other areas, further mass accretion or dynamical compression would be necessary for future high-mass star formation. This is consistent with the current star formation activity. Using the (CO)-C-12 data, we demonstrate that our data have enough capability to identify molecular outflows, and for the Aquila Rift we identify four new outflow candidates. The scientific results will be discussed in detail in separate papers.