[{_id:ObjectId("61cae11f8fc0b2e3b045be04"),location:"Station One",datetime:ISODate("2019-02-02T12:54:57.937Z"),sensorType:"temperature",value:-1.8,__v:0},{_id:ObjectId("61cae11f8fc0b2e3b045be05"),location:"Station two",datetime:ISODate("2019-02-02T09:49:39.200Z"),sensorType:"temperature",value:-2,__v:0},]

db.collection.aggregate([{$sort:{location:1,value:1}},{$group:{_id:{location:"$location"},min:{$first:"$$ROOT"},max:{$last:"$$ROOT"}}},{$project:{_id:1,max:{value:"$max.value",datetime:"$max.datetime"},min:{value:"$min.value",datetime:"$min.datetime"}}}])