What combination of data sources helped confirm the massive, previously undetected local molecular cloud system?

Faint infrared emission from dust combined with carbon monoxide tracers

The massive molecular cloud system located near our local stellar neighborhood remained hidden for a long time primarily because it is cold and non-luminous, absorbing background light. Its eventual confirmation relied on specialized techniques capable of probing these cold environments. Researchers utilized observations mapping the faint infrared emission specifically originating from its embedded dust component. This data was crucial when combined with gas tracers, particularly observations of the carbon monoxide ($ ext{CO}$) molecule, which allows astronomers to map the presence and distribution of the otherwise invisible molecular gas.