ancillary science program



The Orion A cloud: target selection

The IN-SYNC Orion survey is currently obtaining APOGEE spectra for radial velocity along the entire Orion A population, from north of the Orion Nebula Cluster to the end of the Orion A filament, i.e., the entire L1641 cluster. This is 6 degrees in the sky, corresponding to more than 40 parsecs. The image below shows the 5 APOGEE plate pointings we selected for the survey.

15 APOGEE fiber plates have been designed to allocate 3450 fibers onto 2697 unique stars down to H=12.5 (0.2 solar masses for sources with moderate extinction).

The selection of the targets has been done giving higher priority to candidate young members (with either MIR excess, or available stellar parameters). This enables us to cover nearly 100% of the young members down to our detection limit for the low-density regions of the cloud. The completeness decreases to about 50% in the core of the Orion Nebula Cluster, where crowding is a limitation due to the large radius for APOGEE fiber collision.