ABOUT LAMBDA

Product Name
ARCADE Sky Map
Mission
ARCADE

Description

The Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE 2) measures the absolute temperature of the cosmic microwave background and astrophysical foregrounds at frequencies from 3 to 90 GHz. Differential radiometers compare the sky intensity to a full-aperture blackbody calibrator maintained within a few mK of the sky temperature. Careful control of the instrumental signature establishes the zero level of the sky maps to an accuracy of several mK (see Table 3 of Fixsen et al. 2011).

The delivered files contain sky maps from the 2006 flight of the ARCADE 2 instrument. Each FITS file 'arc2_fffff_v19.fits' consists of a sky map in Galactic coordinates with units K thermodynamic temperature. The string "fffff" denotes thecenter frequency in MHz, so for example file arc2_9720_v19.fits contains the sky map from the 9720 MHz channel. There are two channels at 29500 MHz with different beam widths. File arc2_29500s_v19.fits has a 4 deg FWHM beam width while file arc2_29500_v19.fits has the same 11.6 deg beam width as all of the other maps.

Each file contains a map in a binary FITS extension; this extension contains two fields:

  • TEMPERATURE contains the absolute sky intensity in units K thermodynamic temperature for each pixel. The CMB dipole has been removed from the maps, but no other Galactic or cosmological source has been removed.
  • N_OBS contains the number of observations within each pixel. Each observation corresponds to 0.5 seconds integration time. Table 2 of Singal et al 2011 lists the corresponding white noise amplitude for each map.

Additional Details

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A service of the HEASARC and of the Astrophysics Science Division at NASA/GSFC
Goddard Space Flight Center, National Aeronautics and Space Administration
HEASARC Director: Dr. Alan P. Smale
LAMBDA Director: Dr. Eric R. Switzer
NASA Official: Dr. Eric R. Switzer
Web Curator: Mr. Michael R. Greason