Objects in the Milky Way

M42 = OrionA = Orion nebula

This emission line nebula is a HII region, consisting of gas which is ionized and excited to emit optical lines by the hot stars which are embedded in it. The entire region lies on the rim of a giant cloud of molecular gas, from which the stars were born. A drift scan on 1.3 GHz on 31 Dec. 2009 shows that the signal is about 0.3 dB above the background.
A missing flux calibration can be substituted by assuming that the system temperature is 50 K and the zenith temperature is 5 K. The antenna temperature at an elevation of 30º is Tsky = 5 K /sin(30º) = 10 K.
With Y = 100.3 dB/10 = 1.071 and TCMB = 2.7 K one gets for the antenna temperature of the nebula:
Tant(M42) = (Y-1) * (Tsys + TCMB + Tsky) = 4.5 K
As the antenna has a sensitivity of about 15 mK/Jy, the radio flux is 300 Jy, somewhat smaller than the literature value of 400 Jy (Shaver & Mills, 1969).

M1 = Tau A = Crab nebula

This emission nebula is the remnant of a supernova explosion, when in 1054 a massive star terminated its life. The gas which was expelleed from the star at high speed collides with the ambient interstellar gas, ionizes and excites it to emit radiation. The core of the star collapses into a rapidly neutron star which flashes out pulses of radiation from the radio to X-rays, like a lighthouse beaming off its light into the surroundings. A drift scan at 1.3 GHz on 31 Dec. 2009 shows a signal of about 0.75 dB above the background. Two short impulses near UT 1749 are of terrestrial origin.
Assuming a system temperature of 50 K and a zenith temperature of 5 K yields the antenna temperature of the sky background at the elevation 26º Tsky = 11.4 K. With Y = 100.75 dB/10 = 1.189 and TCMB = 2.7 K one gets the source's antenna temperature: Tant(M1) = 12.1 K and the radio flux 805 Jy, in good agreement with the literature value 930 Jy (Kellermann et al. 1969).

Pulsars

Inside the Crab nebula, there sits a pulsar: the rapidly spinning neutron star is another left-over of the supernova explosion, being the remains of the core of the progenitor star. It emits a narrow beam of radiation into its suroundings, like the beam of a lighthouse. 30 times a second, this beam hits the Earth and a radio flash is observed ...

The plot shows the pulse of a different pulsar - B0329+54, the strongest on in the northern sky, with a period of 0.7145 s. More about Our pulsar observations

Cas A

This strong radio source is also a supernova remnant probably from 1667. In the optical only thin filaments are observed. Radio emission comes from the hot gas inside the nebula, whose electrons spiral around the magnetic field lines and produce (non-thermal) synchrotron continuum emission. The drift scan at 1.3 GHz of 31 Dec. 2009 reveals a signal of about 1.7 dB above the background
We may assume a system temperature of 50 K and a zenith temperature of 5 K. The antenna temperature of the sky background at the elevation of 83º is Tsky = 5 K. From Y = 101.7 dB/10 = 1.48 one gets the source antenna temperature Tant(Cas A) = 27.6 K and the radio flux 1840 Jy, which is somewhat smaller than the value from the literature 2580 Jy (Vinogradova et al. 1971).

The Widths of the Profiles

The measured profiles are rather similar. A drift scan of a point source maps the pattern of the antenna's main lobe, which can be well represented by a Gaussian function. The full widths at half maximum (FWHM) are:
Object Declination FWHM FWHM (corr.) Diameter [º]
Orion A -5 1.78 1.78 1.2
Crab 22 1.89 1.75 0.1
Cas A 58 3.33 1.76 0.1
The profile's width which is measured by the time it takes the object to pass through the main lobe, is corrected for the declination of the source in order to get the true angular width: FWHM * cos(Dec). Solar measurements gave the width of the antenna beam (HPBW) as 1.8..1.9º. Only the large Orion nebula could have marginally been resolved by our 1 GHz antenna. The profiles of the point sources Crab and Cas A agree with the antenna's HPBW.