Foreground: Maipu and MU
Maipu and MU Radar 45 MHz Map
HEALPix, nested, res 6 (Nside=64)
2.4° to 4.6°
Original Data Source:
Guzmán et al. (2011) produced an all-sky map of 45 MHz emission by combining data from the 45 MHz survey of Alvarez et al. (1997) between declinations -90° and +19.1° with data from the 46.5 MHz survey of Maeda et al. (1999) between declinations +5° and +65°. The southern survey was made with the Maipu Radio Astronomy Observatory 45-MHz array with a beam of 4.6° (right ascension) x 2.4° (declination) FWHM. The northern survey was made with the Japanese Middle and Upper atmosphere (MU) radar array with a beam of 3.6° x 3.6°.
The Centre d'Analyse de Données Etendues group used the Guzmán et al. brightness temperature data on a Galactic coordinate grid from the Max Planck Institute for Radioastronomy Survey Sampler site to form an all-sky HEALPix format map following the method described in Appendix A of Paradis et al. 2012, A&A, 543, 103, ADS. Their HEALPix map is mirrored here.
Monsalve et al. 2021, ApJ, 908, 145, ADS determined scale and zero-level corrections to the 45 MHz map based on comparison with measurements from the Experiment to Detect the Global EoR Signature (EDGES). They found that the map of Guzmán et al. requires a scale correction of 1.076 ± 0.034 (2σ) and a zero-level correction of -160 ± 78 K (2σ) to best fit the EDGES data. These correction factors have not been applied to the map that is hosted here.
More details can be found in:
Guzmán et al. 2011, A&A, 525, A138, ADS
Maeda et al. 1999, A&AS, 140, 145, ADS
Alvarez et al. 1997, A&AS, 124, 315, ADS