Airborne Thematic Mapper (ATM)

• ATM Background information:

  The NERC Airborne Research and Survey Facility (ARSF) has flown two ATM instruments over the period 1982 - present: the Daedalus 1268 was operated from 1982 until 1998. Since 1996 an upgraded version - the Azimuth Systems AZ-16 has been used, along with an improved data acquisition system.

  The eleven spectral channels of these instruments cover the visible and near-infrared (Chs: 1-8), shortwave infrared (SWIR - Chs: 9 & 10) and thermal infrared (TIR - Ch: 11) many of which closely match the seven channels of the Landsat Thematic Mapper satellite (see Fig.1 and Table 1):

  ATM Band	Spectral range (μ m)	Equivalent Landsat TM band
  1	0.42 - 0.45
  2	0.45 - 0.52	1
  3	0.52 - 0.60	2
  4	0.605 - 0.625
  5	0.63 - 0.69	3
  6	0.695 - 0.75
  7	0.76 - 0.90	4
  8	0.91 - 1.05
  9	1.55 - 1.75	5
  10	2.08 - 2.35	7
  11	8.5 - 13.0#	6
  12	Spare thermal channel

  Table 1. Band characteristics of the Daedalus 1268 Airborne Thematic Mapper instrument compared to those of the Landsat Thematic Mapper instrument. [# Thermal band broadened for aircraft operation.]

  

  Figure 1. Comparison of ATM and LANDSAT-7 bands in the visible and near-infrared spectrum. ATM band 11 (not shown) is in the thermal infrared region, spanning 8400-11500 nm. Landsat-7 Band 8 (not shown) is a panchromatic band spanning the region 520-900 nm.

  Comparative Specifications of the Airborne Thematic Mapper - in its Daedalus 1268 and AZ-16 configurations?are provided in Table 2, below:

  	Daedalus 1268	AZ-16
  Operational period	1982-1985	1996-present
  IFOV	2.5 mrad	2.5 mrad
  Pixel swath	716	992/1984
  Digitised FOV	86 °	90 °
  S-bend correction	73 °
  Scan rate	12.5, 25, 50 Hz	12.5, 25, 50 Hz
  Roll correction	+/-15 °
  Resolution	8-bit (0-255)	16-bit (0-65535)
  Thermal channel calibration	Two black bodies

  Table 2. Comparison of Daedalus 1268 and AZ-16 systems.

  A fully automated Integrated Data System (IDS) was commissioned in late 1998/early 1999 and can now routinely provide geometrically registered, radiometrically calibrated data for both the multi-spectral ATM and the hyper-spectral CASI systems as operated by the NERC Airborne Research and Survey Facility.