Montag, 1. Mai 2017

Radio Galaxy Hercules A (3C348) detected ?

3C348 - Scanning the sky by 1420 MHz ( SPA  GE)

Radio Galaxy Hercules A (3C348) detected?

During the acquisition of data for our sky scanning map, a maximum on 10th February 2017 was observed for RA 16h 50' and DEC around 5° (little uncertainty due to the oscillation of the messed altitude value got from a 10DOF chip, see site ) about 50 KHz underneath the first vestiges of the neutral hydrogen emissions of the Milky Way by 1420.406 MHz Our records were compared with the data published through the Vizier Databank on this site. We found a mismatch by the position of all detected signals (perhaps also width) around the 1420.406 MHz, as if our
Spectrum was twice wider than it should. The source of error will be investigated and eliminated. Nevertheless it seems that the relative position of our detections to the 21cm not Doppler shifted frequency is correct. 

Following plots show the mentioned received signal under investigation in this report:

Figure 1: Calculated Power and Frequency of detected signals along the day 10th eb 2017
The plot is a composition with data calculated from the scans recorded along the day. In upper side we can see the estimated signal power (calculated via integration of detected signal area in the scan without calibration with the messed antenna temperature). Over the graph you find the name of known radio sources near antenna focus, every one of them in the corresponding color depending on its flux density (information extracted from NRAO survey) and with a distance to the belonging plot point, depending on its distance to antenna focus. The name of known sources does not imply that we also detected the transit of this object. On the lower side we see the area of detected signal in light blue and the position of found peaks inside this area with variable color, which depends on detected amplitude. The right side reveals the amplitude of peak, color-coded.

Around the expected time of Herc A transit there is a second peak on the scan and the estimated signal power graph shows also a little but perceivable rise. A zoom of this area:

Figure 2: Power of detected signal and peaks position around the supoused transit of 3C348

Next plot shows another point of view, the 2D-projection of all recorded scans (spectrums) along the day. The Y-axis was replaced by the scanned RA coordinate. The information published in Wikipedia about RA-DEC coordinates of Herc A gives us RA 16h 51m 08.15s and DEC +04° 59' 33.32''. This area was zoomed and the expected transit is again visible. 

Figure 3: 2D-Projection of spectrum superposition along the 10th Feb 2017

Figure 4: Zommed area from Plot 3 around the 3C348 coordinates

The maximum was found on this day at 7:00 local time and a comparison with the data extracted from Vizier Catalog lets us see, despite of the frequency mismatch mentioned before, an analogy. 

Figure 5: Recorded spectrum (possibly of 3C348) for time of maximum

Figure 6: Spectrum published in Vizier for 3C348

Other comparisons with Vizier data were made for following radio sources:

  • 3C138

Figure 7: Spectrum recorded during transit of 3C138

Figure 8: Spectrum of 3C138 found in Vizier Catalog


Figure 9:  Spectrum recorded during transit of  4C13.67

Figure 10:  Spectrum of 4C13.67 found in Vizier Catalog

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