Wilkinson Microwave Anisotropy Probe

The data made available through this page has been updated. The most recent version of this data may be accessed through /product/map/current/

Collage image of the Microwave Anisotropy Probe (MAP) images and data.

FIRST-YEAR DATA
FIRST-YEAR PAPERS
COSMOLOGICAL PARAMETERS TABLE
WMAP MISSION SITE

WMAP Overview

The WMAP (Wilkinson Microwave Anisotropy Probe) mission is designed to determine the geometry, content, and evolution of the universe via a 13 arcminute FWHM resolution full sky map of the temperature anisotropy of the cosmic microwave background radiation. The choice of orbit, sky-scanning strategy and instrument/spacecraft design were driven by the goals of uncorrelated pixel noise, minimal systematic errors, multifrequency observations, and accurate calibration. The skymap data products derived from the WMAP observations have 45 times the sensitivity and 33 times the angular resolution of the COBE DMR mission. The WMAP mission characteristics are summarized in the table below.

WMAP Mission Characteristics:
	K-Band^a	Ka-Band^a	Q-Band^a	V-Band^a	W-Band^a

Wavelength (mm)^b	13	9.1	7.3	4.9	3.2
Frequency (GHz)^b	23	33	41	61	94
Bandwidth (GHz)^{b, c}	5.5	7.0	8.3	14.0	20.5
Number of Differencing Assemblies	1	1	2	2	4
Number of Radiometers	2	2	4	4	8
Number of Channels	4	4	8	8	16
Beam size (deg)^{b, d}	0.88	0.66	0.51	0.35	0.22
System temperature, Tsys (K)^{b, e}	29	39	59	92	145
Sensitivity (mK sec^½ )^b	0.8	0.8	1.0	1.2	1.6

Sky coverage	Full sky
Optical system	Back-to-Back Gregorian, 1.4 x 1.6 m primaries
Radiometric system	differential polarization sensitive receivers
Detection	HEMT amplifiers
Radiometer Modulation	2.5 kHz phase switch
Spin Modulation	0.464 rpm = ~ 7.57 mHz spacecraft spin
precession Modulation	1 rev hr ^-1 = ~ 0.3 mHz spacecraft precession
Calibration	In-flight: amplitude from dipole modulation, beam from Jupiter
Cooling system	passively cooled to ~ 90 K
Attitude control	3-axis controlled, 3 wheels, gyros, star trackers, sun sensors
Propulsion	blow-down hydrazine with 8 thrusters
RF communication	2 GHz transponders, 667 kbps down-link to 70 m DSN
Power	419 Watts
Mass	840 kg
Launch	Delta II 7425-10 on June 30, 2001 at 3:46:46.183 EDT
Orbit	1° - 10° Lissajous orbit about second Lagrange point, L2
Trajectory	3 Earth-Moon phasing loops, lunar gravity assist to L2
Design Lifetime	27 months = 3 month trajectory + 2 yrs at L2

	^a Commercial waveguide band designations used for the five MAP frequency bands
	^b Typical values for a radiometer are given.
	^c Effective signal bandwidth.
	^d The beam patterns are not Gaussian, and thus are not simply specified. The size given here is the square- root of the beam solid angle.
	^e Effective system temperature of the entire system.

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Wilkinson Microwave Anisotropy Probe