US focused oil group Nighthawk flew higher Monday after an independent valuation estimated oil in place at its Jolly and Craig Ranch fields to be 1.462 billion barrels gross.Nighthawk has a 50% stake in the fields, part of the Jolly Ranch project, Lincoln County, Colorado.Broker Ambrian called it a "positive" for the company and suggests a recoverable volume of oil net to Nighthawk of 128.6 million barrels, "a material number for company of Nighthawk's size". It maintains 'buy' advice and 62p price target.