Absorption and Emission Spectra Towards Continuum Background Sources in the CGPS

Below you will find the ON and OFF source spectra obtained towards CGPS continuum sources at 1420 MHz. All sources with peak continuum brightness temperature (before removing any foreground continuum) above 30 K in the CGPS region are included. To obtain the foreground continuum subtraced source brightness, and the ON and OFF spectra the continuum sources were fitted with an elliptical Gaussian. The continuum brightness temperature (Tbg) of the sources was taken to be the peak value minus the baselevel of the Gaussian. Each ON-source data point is the average of all the pixels within one HWHM from the source centre position plus pixels outside of that distance with signal to noise higher than 5. The OFF-spectrum is the average of all the pixels in an annulus of 1 arcminute width around the source. The inner edge of the annulus is 2 HWHM from the centre and follows the same elliptical shape as the fitted Gaussian ( FIGURE).

Summary:

There are a total of 405 sources.
File names reflect the Galactic coordinates of the sources (l_b.dat)
First line of each file is a header containing
- l (deg), b (deg), Tbg (K)
Each file has 7 columns:
- LSR velocity (km/s)
- T_OFF (K) - Average emission brightness temp. in the annulus
- T_ON (K) - Average on-source brightness temperature
- exp(-tau) - Optical depth
- dT_OFF (K) - Uncertainty in T_OFF. Given by (annulus RMS)/(# beams in annulus)
- dT_ON (K) - Uncertainty in T_ON. Given by annulus RMS.
- dexp(-tau) - Uncertainty in optical depth. Analytically calculated from dT_OFF and dT_ON
For a detailed description of the spectra extraction and error calculations please see my thesis.

References:

Strasser, S.T., Taylor, A.R., "1420 MHz Continuum Absorption Towards Extragalactic Sources in the Galactic Plane" (2003), ApJ, 603, 560.
DOWNLOAD current PDF version.
Strasser. S.T., MSc Thesis (2002), University of Calgary.
DOWNLOAD postscript version.
Strasser, S.T., Taylor, A.R. (2002), ASP Conference Series, 276, 145.
Taylor, Gibson, S. J., Peracaula, M., Martin, P. G., Landecker, T. L., Brunt, C. M., Dewdney, P. E., Dougherty, S. M., Gray, A. D., Higgs, L. A., Kerton, C. R., Knee, L. B. G., Kothes, R., Purton, C. R., Uyaniker, B., Wallace, B. J., Willis, A. G., Durand, D., "The Canadian Galactic Plane Survey" (2003), AJ, 125, 3145.

DOWNLOAD DATA here. Please cite first and/or second Reference if you use the spectra.

Simon Strasser

Last modified: Mon Jun 14 13:13:11 CDT 2004