J/A+AS/135/273 408MHz obs. of GPS sources from JVAS survey (Marecki+ 1999) ================================================================================ Gigahertz Peaked Spectrum sources from the Jodrell Bank-VLA Astrometric Survey I. Sources in the region 35{deg}<={delta}<=75{deg} Marecki A., Falcke H., Niezgoda J., Garrington S.T., Patnaik A.R. =1999A&AS..135..273M (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Radio sources Keywords: catalogs - galaxies: active - quasars: general - radio continuum: general Abstract: Observations with MERLIN at 408 MHz have been used to establish the low-frequency part of the spectra of more than a hundred compact radio sources taken from the part of the Jodrell Bank-VLA Astrometric Survey (JVAS) limited by 35{deg}<={delta}<=75{deg}. These sources were selected from JVAS and other catalogues to have convex spectra between 1.4 and 8.4GHz, characteristic of Gigahertz Peaked Spectrum sources. We have confirmed convex shapes of the spectra of 76 objects. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 46 98 Subsample Two - flux densities at 408 MHz table3.dat 41 27 Subsample Two - sources not measured at 408 MHz table4.dat 61 76 GPS sources' spectra fitting parameters -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 8 A8 --- IAU IAU name 11- 12 I2 h RAh Right ascension (J2000) 14- 15 I2 min RAm Right ascension (J2000) 17- 23 F7.4 s RAs Right ascension (J2000) 26- 27 I2 deg DEd Declination (J2000) 29- 30 I2 arcmin DEm Declination (J2000) 32- 37 F6.3 arcsec DEs Declination (J2000) 40- 42 I3 mJy S408MHz Flux density at 408 MHz 45- 46 A2 --- Type Object type (1) -------------------------------------------------------------------------------- Note (1): BL: BL Lac object BS: blue stellar object (without the spectrum - basically a quasar) BG: blue galaxy? CW: crowded field - too many objects for a clean identification EF: empty field G: galaxy NS: neutral stellar object (same magnitude in both E and O prints) OB: obscured field Q: quasar RS: red stellar object -------------------------------------------------------------------------------- Byte-by-byte Description of file: table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 8 A8 --- IAU IAU name 11- 12 I2 h RAh Right ascension (J2000) 14- 15 I2 min RAm Right ascension (J2000) 17- 23 F7.4 s RAs Right ascension (J2000) 26- 27 I2 deg DEd Declination (J2000) 29- 30 I2 arcmin DEm Declination (J2000) 32- 37 F6.3 arcsec DEs Declination (J2000) 40- 41 A2 --- Type Object type (1) -------------------------------------------------------------------------------- Note (1): BL: BL Lac object BS: blue stellar object (without the spectrum - basically a quasar) BG: blue galaxy? CW: crowded field - too many objects for a clean identification EF: empty field G: galaxy NS: neutral stellar object (same magnitude in both E and O prints) OB: obscured field Q: quasar RS: red stellar object -------------------------------------------------------------------------------- Byte-by-byte Description of file: table4.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 2 I2 --- Seq Sequence number on our list 5- 12 A8 --- IAU IAU name 15- 20 F6.1 mJy S0 S_0_ parameter (1) 23- 28 F6.3 GHz nu0 {nu}_0_ parameter (1) 31- 37 F7.4 --- k Spectral index of the rising part 40- 45 F6.3 --- l Spectral index of the declining part 48- 51 I4 mJy Smax ? Flux density at the maximum 54- 58 F5.3 GHz numax ? Frequency of the maximum flux density 61- 61 A1 --- Flag Note (2) -------------------------------------------------------------------------------- Note (1): S_0_ and nu_0_ are just parameters in the formula (2): S({nu})=S_0_/(1-e^-1^)*({nu}/{nu}_0_)^k^*(1-e^-({nu}/{nu}_0_)^l-k^) Note (2): We fitted the so called broken power-law to our spectra - see formula (2) in the paper. Even though it seems to be the physically more sensible choice for a model spectrum compared to a simple second-order polynomial, it has the disadvantage that it is unconstrained if the peak of the spectrum falls beyond the 2nd highest or below the 2nd lowest available frequency. In these cases we fixed the peak of the model spectrum (i.e. Smax and numax) at the peak of the measured data - this was usually the measurement at 4.85GHz - and marked the fit as "unconstrained" by putting a "+" sign in col. 61. -------------------------------------------------------------------------------- Acknowledgements: Andrzej Marecki ================================================================================ (End) Patricia Bauer [CDS] 02-Mar-1999