Dear fellow MARMAMers, "MMO Range Finder" app for iPhone and iPad is now available on the AppStore. I developed this app to help MMOs like myself quickly calculate the horizontal distance from the animal to the source providing an instant decision making tool for mitigation. What makes it different from basic Trigonometry apps is that it takes two bearings and calculates the angle for you, allowing your brain to focus on the task at hand. See blurb below for more info. If you have any queries, qualms or questions I'd be delighted to hear from you. Link to App Store https://appsto.re/au/PRVblb.i Many thanks, James Marine Mammal Observers mitigate for the potential impact of sound exposure on marine fauna during seismic surveys, UXO clearance or civil engineering projects. A fundamental function of the observer is to calculate the distance of an animal to the source of noise irrespective of their own position and recommend actions based on specified mitigation zones around the source of the sound. This app calculates the distance from the animal (Target) to the origin of the sound (Source) using a trigonometric cosine function. The user simply enters the distance and bearing to the Target and Source from their observation position and the app calculates the rest. The user can enter all data manually using either relative or true bearings (in degrees) and distances (in metres) they have estimated using standard methodology (reticule binoculars, range finding stick etc). The user can also use their devices in-built compass to automatically fix bearings by simply pointing towards the Target or Source and clicking the relevant "Fix" buttons (Target; top-left button or Source; top-right button). Pressing solve returns the answer in metres. When Location Services are enabled and the device has good GPS satellite connectivity (Settings>Privacy>Location Services) the app displays the users current position, course over ground (COG) and speed over ground (SOG). This output can be calibrated in Settings>Range Finder as follows; Coordinate format in DD.DDD°, DD° MM' SS" or DD° MM.MM'. Speed in knots (kts) or kilometres per hour (km/h). Should the user have concern about compass interference they can set the compass (also in Settings>Range Finder) to read True North instead of Magnetic North. This requires Locations Services to be enabled. There is a screenshot button in the bottom right corner to allow the user to save data for their records. MMO Range Finder App should be used as a reference tool and is only as precise as the users ability to range find. Any decision making is the responsibility of the user. If in use, the compass and location should be verified often. James Keating, PhD Marine Ecological Consultant Perth, Western Australia +61 (0) 47 5075340 keating.marine@gmail.com