A 45-MHz continuum survey of the northern hemisphere

Maeda, K.; Álvarez, H.; Aparici, J.; May, J.; Reich, P.

doi:10.1051/aas:1999413

Cited by 73 publications

(70 citation statements)

References 17 publications

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“…Both the Haslam map and the GSM have become widely used and cited in both simulations and data reduction pipelines for redshifted 21 cm observations (Bowman, Morales, & Hewitt 2009;Patra et al 2013;Subrahmanyan & Cowsik 2013;Thyagarajan et al 2015;Bernardi et al 2016). Guzmán et al 2011 created an all-sky temperature map at 45 MHz based upon the surveys of Alverez et al (1997) and Maeda et al (1999). In addition, they produced an allsky Galactic spectral index map based upon two frequency points by using their 45 MHz and the Haslam 408 MHz map after corrections for zero-level, extragalactic non-thermal emission, and CMB factors.…”

Section: Introductionmentioning

confidence: 99%

Improved measurement of the spectral index of the diffuse radio background between 90 and 190 MHz

Mozdzen¹,

Bowman²,

Monsalve³

et al. 2016

Mon. Not. R. Astron. Soc.

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We report absolutely calibrated measurements of diffuse radio emission between 90 and 190 MHz from the Experiment to Detect the Global EoR Signature (EDGES). EDGES employs a wide beam zenith-pointing dipole antenna centred on a declination of −26.7 • . We measure the sky brightness temperature as a function of frequency averaged over the EDGES beam from 211 nights of data acquired from July 2015 to March 2016. We derive the spectral index, β, as a function of local sidereal time (LST) and find −2.60 > β > − 2.62 ±0.02 between 0 and 12 h LST. When the Galactic Centre is in the sky, the spectral index flattens, reaching β = −2.50 ±0.02 at 17.7 h. The EDGES instrument is shown to be very stable throughout the observations with night-to-night reproducibility of σ β < 0.003. Including systematic uncertainty, the overall uncertainty of β is 0.02 across all LST bins. These results improve on the earlier findings of by reducing the spectral index uncertainty from 0.10 to 0.02 while considering more extensive sources of errors. We compare our measurements with spectral index simulations derived from the Global Sky Model (GSM) of de Oliveira-Costa et al. (2008) and with fits between the Guzmán et al. (2011) 45 MHz andHaslam et al. (1982) 408 MHz maps. We find good agreement at the transit of the Galactic Centre. Away from transit, the GSM tends to over-predict (GSM less negative) by 0.05 < ∆ β = β GSM − β EDGES < 0.12, while the 45-408 MHz fits tend to over-predict by ∆ β < 0.05.

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Section: Introductionmentioning

confidence: 99%

Improved measurement of the spectral index of the diffuse radio background between 90 and 190 MHz

Mozdzen¹,

Bowman²,

Monsalve³

et al. 2016

Mon. Not. R. Astron. Soc.

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“…The accuracy of the GSM is given to 1-10 % depending on frequency and sky region. For our observation frequency the GSM is highly dependent on the 45 MHz surveys of Maeda et al (1999), which have been performed with the MU radar for the Northern declinations and on Roger et al (1999) using the 22 MHz DRAO radio telescope. The angular resolution and beam width in both surveys is better than the beam width we used for the observations with MAARSY.…”

Section: Comparison Of a Single Day Data Set Of Observations With A Gmentioning

confidence: 99%

Validation of the radiation pattern of the Middle Atmosphere Alomar Radar System (MAARSY)

et al. 2012

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The Middle Atmosphere Alomar Radar System (MAARSY) allows studies with high spatial and temporal resolution in the troposphere/lower stratosphere and in the mesosphere/lower thermosphere of the Arctic atmosphere. The monostatic radar is operated at 53.5 MHz with an active phased array antenna consisting of 433 Yagi antennas. Each individual antenna is connected to its own transceiver with independent phase control and a scalable power output of up to 2 kW, which implies high flexibility of beam forming and beam steering. During the design phase of MAARSY several model studies have been carried out in order to estimate the radiation pattern for various combinations of beam forming and steering. However, parameters like mutual coupling, active impedance and ground parameters have an impact on the radiation pattern, but can hardly be measured. Hence, experiments need to be designed to verify the model results. For this purpose, the radar has occasionally been used in passive mode, monitoring the noise power received from both distinct cosmic noise sources like e.g. Cassiopeia A and Cygnus A, and the diffuse cosmic background noise. The analysis of the collected dataset enables us to verify beam forming and steering attempts. These results document the current status of the radar during its development and provide valuable information for further improvement.

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“…Note that (S sys + S sky ) must be evaluated at the same time resolution as the measurements of P r , while DS sky is a single number evaluated by considering the daily variation of the noise over several days, to eliminate effects of interference and anomalous absorption of the sky noise (primarily a problem in Kiruna). DT sky is estimated using published maps of calibrated surveys of the radio-sky at 45 MHz [Maeda et al, 1999;Alvarez et al, 1997]. Values at 45 MHz are reduced by the expected frequency dependence of galactic noise ( f À2.8 ) and by a factor 2 since we receive only a single polarisation [see e.g., Ellington, 2005].…”

Section: Calculation and Cross-calibration Of Pmse Volume Reflectivitiesmentioning

confidence: 99%

Polar mesosphere summer echoes at Wasa, Antarctica (73°S): First observations and comparison with 68°N

Kirkwood

Wolf

Nilsson

et al. 2007

Geophysical Research Letters

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A 45-MHz continuum survey of the northern hemisphere

Cited by 73 publications

References 17 publications

Improved measurement of the spectral index of the diffuse radio background between 90 and 190 MHz

Improved measurement of the spectral index of the diffuse radio background between 90 and 190 MHz

Validation of the radiation pattern of the Middle Atmosphere Alomar Radar System (MAARSY)

Polar mesosphere summer echoes at Wasa, Antarctica (73°S): First observations and comparison with 68°N

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