code: def isPositiveMap(self):
          
          x0, y0 = self.skyToPix(self.ra0_deg, self.dec0_deg)
          x1, y1 = self.skyToPix(self.ra0_deg + 1/3600., self.dec0_deg)
  
          if x1 > x0:
              return True
          return False
docs: Returns true if increasing ra increases pix in skyToPix()