Opportunity is exploring 'Marathon Valley' located on the rim of Endeavour crater. The objective is to identify specific outcrops for evidence of clay minerals.

Opportunity has completed a mini-'walkabout' with extensive imaging of the region and is now beginning the in-situ (contact) investigation.

On Sol 4345 (April 14, 2016), the rover moved just about 8 feet (2.5 meters), approaching a target for investigation with the robotic arm instruments.

On Sol 4347 (April 16, 2016), Opportunity used the robotic arm to collect a Microscopic Imager (MI) mosaic of the surface target, named 'Pierre Pinaut.'

This was followed by the placement of the Alpha Particle X-ray Spectrometer (APXS) on the same target for a multi-hour integration.

In between these activities, the rover continues to collect extensive Panoramic Color (Pancam) color panoramas, Navigation Camera (Navcam) panoramas and targeted multi-filter images.

On Sol 4350 (April 19, 2016), Opportunity attempted to collect additional MI mosaics, but a goal error occurred because the first image with the MI camera did not complete.

This is an anomaly that has seen before where a camera image fails to complete. The project is investigating this and is preparing diagnostics to run on the camera system.

As of Sol 4350 (April 19, 2016), the solar array energy production is 635 watt-hours with an atmospheric opacity (Tau) of 0.461 and a solar array dust factor of 0.762.

Total odometry is 26.58 miles (42.78 kilometers), more than a marathon.