Date range query for past 24 hour in Mongo shell

Found answer here: https://stackoverflow.com/questions/1296358/subtract-days-from-a-date-in-javascript

db.system.profile.find({ 
  "timestamp" : { 
    $lt: new Date(), 
    $gte: new Date(new Date().setDate(new Date().getDate()-1))
  }   
})

db.system.profile.find({ 
 "timestamp" : 
    {     
        $gte:   new Date(new Date().setHours(00,00,00)) ,     
        $lt :  new Date(new Date().setHours(23,59,59)) 
   } 
})