About ETM+
The Enhanced Thematic Mapper Plus (ETM+) is the main instrument on board Landsat-7 and has been operational since 1999.
ETM+ is an 8-band whiskbroom scanning radiometer consisting of:
- A primary mirror that sweeps side-to-side (across-track) to produce forward and reverse image scans, and
- A Scan Line Corrector (SLC) mirror assembly that sweeps forward-to-back to compensate for the forward motion of the spacecraft during integration time. The motion of these mirrors deviates from an ideal line profile, introducing along- and cross-track geometric distortions that require compensation.
The principal functional differences between the ETM+ and the former TM series are the addition of a 15 m resolution panchromatic band and two 8-bit "gain" ranges. The ETM+ adds a 60 m resolution thermal band, replacing the 120 m band on ETM/TM (band Number 6). ETM+ data therefore cover the visible, Near Infra-Red (NIR), shortwave, and Thermal Infra-Red (TIR) spectral bands of the electromagnetic spectrum.
ETM+ Instrument Parameters
Swath Width |
185 km |
Spatial Resolution |
15 m PAN
30 m VNIR/SWIR
60 m TIR |
Sensor Modes
Landsat operated in the SAM (Scan Angle Monitor) Mode for nominal routine operations. On 1 April 2007, Landsat-7 was switched to the 'backup' BUMPER mode to help correct issues associated with the end of an instruments lifetime. More information on this mode-switch is available in the monthly update from April 2002.
TM Band Information
Band No. |
Wavelength (µm) |
|
8 |
0.52 - 0.90 |
PAN |
1 |
0.45 - 0.52 |
(VIS, blue) |
2 |
0.53 - 0.61 |
(VIS, green) |
3 |
0.63 - 0.69 |
(VIS, red) |
4 |
0.77 - 0.90 |
NIR |
5 |
1.55 - 1.75 |
SWIR |
7 |
2.08 - 2.35 |
SWIR |
6 |
10.4 - 12.5 |
TIR |