We present the metallicities and carbon abundances of four newly discovered metal-poor stars with -2.2 < [ Fe/H ] < -1.6 in the Sagittarius dwarf spheroidal galaxy .
These stars were selected as metal-poor member candidates using a combination of public photometry from the SkyMapper Southern Sky Survey and proper motion data from the second data release from the Gaia mission .
The SkyMapper filters include a metallicity-sensitive narrow-band v filter centered on the Ca II K line , which we use to identify metal-poor candidates .
In tandem , we use proper motion data to remove metal-poor stars that are not velocity members of the Sagittarius dwarf spheroidal galaxy .
We find that these two datasets allow for efficient identification of metal-poor members of the Sagittarius dwarf galaxy to follow-up with further spectroscopic study .
Two of the stars we present have [ Fe/H ] < -2.0 , which adds to the few other such stars currently identified in the Sagittarius dwarf galaxy that are likely not associated with the globular cluster M54 , which resides in the nucleus of the system .
Our results confirm that there exists a very metal-poor stellar population in the Sagittarius dwarf galaxy .
We find that none of our stars can be classified as carbon-enhanced metal-poor stars .
Efficiently identifying members of this population will be helpful to further our understanding of the early chemical evolution of the system .