Remove giblets and neck from the turkey; reserve for other uses, if desired. Rinse turkey with cold water and pat dry.
Loosen skin from the turkey breast a bit, but not totally detaching. Place rosemary and sage under skin, then smooth skin over the herbs and back into place.
Place apple, celery and onion into the neck cavity. Place the turkey, breast side up on a rack in a shallow roasting pan and brush with melted butter. Cover turkey loosely with an aluminum foil "tent" or place into a turkey size cooking bag.
Bake at 325 degrees F until meat thermometer registers about 180 degrees F. This should take from 3 1/2 to 4 hours, but begin checking after 3 hours. Remove turkey and let stand 15 minutes before carving.