NOAA-15 is one of the NASA-provided TIROS

TIROS

TIROS, or Television Infrared Observation Satellite, is a series of early weather satellites launched by NASA, beginning with TIROS-1 in 1960. TIROS was the first satellite that was capable of remote sensing of the Earth. This initial remote-sensing effort was significant because it enabled Earth...

 series of weather forecasting satellite run by NOAA. It was launched on 13 May 1998, and is currently operational, in a sun-synchronous orbit

Sun-synchronous orbit

A Sun-synchronous orbit is a geocentric orbit which combines altitude and inclination in such a way that an object on that orbit ascends or descends over any given point of the Earth's surface at the same local mean solar time. The surface illumination angle will be nearly the same every time...

, 807 km above the Earth, orbiting every 101 minutes. It hosts the AMSU

Advanced Microwave Sounding Unit

The Advanced microwave sounding unit is a multi-channel microwave radiometer installed on meteorological satellites. The instrument examines several bands of microwave radiation from the atmosphere to perform atmospheric sounding of temperature and moisture levels.-Products:Level-1 radiance data...

-A and AMSU-B instruments, the AVHRR and High Resolution Infrared Radiation Sounder (HIRS/3) instruments, as well as a Space Environment Monitor (SEM/2).

APT

Automatic Picture Transmission

The Automatic Picture Transmission system is an analog image transmission system developed for use on weather satellites. It was introduced in the 1960s and over four decades has provided image data to relatively low-cost user stations at locations in most countries of the world...

 transmission frequency is 137.62 MHz. Due to problems with the S-band transmitter high-gain antennas, NOAA-15 has been configured for High Resolution Picture Transmission

High resolution picture transmission

Weather satellite pictures are often broadcast as High Resolution Picture Transmissions , Color High Resolution Picture Transmissions for Chinese Weather Satellite transmissions or Advanced High Resolution Picture Transmissions for EUMETSAT Weather Satellite transmissions...

using the S-Band Transmitter #2 (1702.5 MHz) omnidirectional antenna.