2008MNRAS.388.1775H

Query : 2008MNRAS.388.1775H

2008MNRAS.388.1775H - Mon. Not. R. Astron. Soc., 388, 1775-1786 (2008/August-3)

Radio source calibration for the Very Small Array and other cosmic microwave background instruments at around 30 GHz.

HAFEZ Y.A., DAVIES R.D., DAVIS R.J., DICKINSON C., BATTISTELLI E.S., BLANCO F., CLEARY K., FRANZEN T., GENOVA-SANTOS R., GRAINGE K., HOBSON M.P., JONES M.E., LANCASTER K., LASENBY A.N., PADILLA-TORRES C.P., RUBINO-MARTIN J.A., REBOLO R., SAUNDERS R.D.E., SCOTT P.F., TAYLOR A.C., TITTERINGTON D., TUCCI M. and WATSON R.A.

Abstract (from CDS):

Accurate calibration of data is essential for the current generation of cosmic microwave background (CMB) experiments. Using data from the Very Small Array (VSA), we describe procedures which will lead to an accuracy of 1 per cent or better for experiments such as the VSA and CBI. Particular attention is paid to the stability of the receiver systems, the quality of the site and frequent observations of reference sources. At 30 GHz the careful correction for atmospheric emission and absorption is shown to be essential for achieving 1 per cent precision.

The sources for which a 1 per cent relative flux density calibration was achieved included Cas A, Cyg A, Tau A and NGC 7027 and the planets Venus, Jupiter and Saturn. A flux density, or brightness temperature in the case of the planets, was derived at 33 GHz relative to Jupiter which was adopted as the fundamental calibrator. A spectral index at ∼30 GHz is given for each.

Cas A, Tau A, NGC 7027 and Venus were examined for variability. Cas A was found to be decreasing at 0.394 ±0.019 per cent/yr over the period 2001 March to 2004 August. In the same period Tau A was decreasing at 0.22±0.07 per cent/yr. A survey of the published data showed that the planetary nebula NGC 7027 decreased at 0.16±0.04 per cent/yr over the period 1967-2003. Venus showed an insignificant (1.5±1.3 per cent) variation with Venusian illumination. The integrated polarization of Tau A at 33 GHz was found to be 7.8±0.6 per cent at position angle =148°±3°.

Journal keyword(s): methods: observational - techniques: interferometric - cosmic microwave background - cosmology: observations - radio continuum: ISM - radio continuum: Solar system

Simbad objects: 7

Full paper

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Number of rows : 7

N	Identifier	Otype	ICRS (J2000) RA	ICRS (J2000) DEC	Mag U	Mag B	Mag V	Mag R	Mag I	Sp type	#ref 1850 - 2026	#notes
1	M 1	SNR	05 34 31.8	+22 01 03						~	6516	1
2	V* CM Tau	Psr	05 34 31.9474694616	+22 00 52.153698024						~	5476	0
3	LDN 1622	DNe	05 54 28	+01 48.2						~	110	0
4	MCG+07-41-003	Bla	19 59 28.35656837	+40 44 02.0972325		16.22	15.10			~	2537	2
5	NGC 7027	PN	21 07 01.571952	+42 14 10.47120		10.358	8.831	10.157		~	2541	1
6	NGC 7293	PN	22 29 38.5454047152	-20 50 13.747242408	11.894	13.158	13.524	13.689	13.898	DAO.5	983	1
7	NAME Cas A	SNR	23 23 26.0	+58 48 41			14.30			~	3033	1

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