We carried out mapping observations toward three nearby molecular clouds , Orion A , Aquila Rift , and M17 , using a new 100 GHz receiver , FOREST , on the Nobeyama 45-m telescope .
In the present paper , 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 ^ { 12 } CO ( J = 1 - 0 ) , ^ { 13 } CO ( J = 1 - 0 ) , C ^ { 18 } O ( J = 1 - 0 ) , N _ { 2 } H ^ { + } ( 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 \sim 20 \arcsec and a velocity resolution of \sim 0.1 km s ^ { -1 } .
Assuming the representative distances of 414 pc , 436 pc , and 2.1 kpc , the maps of Orion A , Aquila Rift , and M17 cover most of the densest parts with areas of about 7 pc \times 15 pc , 7 pc \times 7 pc , and 36 pc \times 18 pc , respectively .
On the basis of the ^ { 13 } CO column density distribution , the total molecular masses are derived to be 3.86 \times 10 ^ { 4 } M _ { \odot } , 2.67 \times 10 ^ { 4 } M _ { \odot } , and 8.1 \times 10 ^ { 5 } M _ { \odot } for Orion A , Aquila Rift , and M17 , respectively .
For all the clouds , the H _ { 2 } column density exceeds the theoretical threshold for high-mass star formation of \gtrsim 1 g cm ^ { -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 ^ { 12 } CO data , we demonstrate that our data have enough capability to identify molecular outflows , and for Aquila Rift , we identify 4 new outflow candidates .
The scientific results will be discussed in details in separate papers .