Landsat-8 operates in the EARTH OBSERVATION mode for nominal routine operations. The satellite acquires all day-lit descending land images between 57° North and 57° South, and on average 90% day-lit descending land images at higher latitudes; combined to approximately 725 images per day. Night, ocean, and day-lit ascending images are only acquired by special request.

Almost all imaging is performed with both the OLI and TIRS instruments. The exception is for some night data, acquired for TIRS calibration and therefore with only the TIRS sensor (identified by a "T" in the product filename). If either the TIRS or OLI is not available, the available sensor that acquired is noted in the filename.

Off-nadir imaging is currently only done at night for TIRS-calibration purposes when it does not impact Nadir day-time imaging; it must be approved by the Data Acquisition Manager, as must the special requests for night, ocean, and day-lit ascending imaging. Having said this, Landsat is not a tasking mission hence; off-nadir daytime acquisitions are mostly resisted since they cost nearly an entire orbit of nadir data.

Learn more about the OLI instrument:

• OLI on the eoPortal*
• OLI on USGS website*

*The information provided is sourced and updated by external entities. For further details, please consult our Terms and Conditions page.