RadioAstronomyAtHome: Scanning the sky by 1420 MHz with FDM-S2

Searching for signals

Current scanned Sky

For this analysis logged data of some days of September 2015 were taken, with the purpose of finding out if there is any significant radio source detectable with the previously described (see older post) handmade radio telescope and a 4m diameter parabolic dish. A complete sky scan is being made, which will probably take some weeks (or even months). Within this post we take first a look on declination -2° 22'.

Declination -2° 22'

The following plot shows the software detector data for the 7th September 2015.

24 Hours Plot of 7th September 2015 for DEC -2° 22'

The plot includes two different representations of the recorded data in these 24 hours. The X-axis contains the timestamp in local form. The Y-axis of the upper plot shows the calculated power in every scan on basis of a developed algorithm, which makes a conversion of the real scan (1420 to 1421MHz) to a flatted scan, tries to recognize the existence of a signal on it and integrates the area of the found signal as a result. For the current scanned sky position (RA-DEC) a possible detectable radio source extracted from 1420MHz catalogue in http://vizier.cfa.harvard.edu/ is logged and shown vertically (mostly not really readable on a 24 hours plot). The color of the text depends on the flux of the source, in Jy. The plot below shows in the left Y-axis the frequency band of found signal on scan, with his corresponding bandwidth on the right side.

For a better recognition of detected radio sources it is always necessary a comparison of data of different days, so that the expected time shifting of 4 minutes per day is obvious. The next picture includes the 7^th and 9^th September:

24 Hours Plot of 7th and 9th September 2015

00h 25min UTC, 3C29 ?

A catalogue of radio sources on 1420 MHz indicates for 3C29 (RA 00h 55min and DEC -01° 42') a Flux of 7Jy.

Radio Sources Catalogue extract with 3C29

The signal detected on 1420.5 MHz that produces the little broad peak on the detector curve is shown here. Time of Scan is 00h 25' 37'' UTC.

Scan 7th Sep 2015 at 00h25min19sec on RA 00h 25min DEC -2° 22'

Sky on 7th Sept 2015 at 00h 25' 37'' UTC for RA 00h 55' DEC -2° 22' (Antenna Focus)

02h 13in UTC, 3C71 ?

Observing the time period between 02:00 and 02:30 UTC we appreciate the peak caused by a signal centered on 1420.5 MHz. The sky view on this time for the scanned area shows several sources, being the starkest one 3C71 or M77 (NGC 1068). This source still lies more than 1° above the antenna focus.

Zoom of plot for a better analysis around 04:13 local or 02:13 UTC

A search through the scanned area with planetarium software lets us guess it could be M77 or even 023507-040205, a very faint radio source, catalogued with just 1495.3 mJy.

Sky on 7th Sept 2015 at 02h 13' UTC for RA 02h 55' DEC -2° 22' (Antenna Focus)

PSK0336-01, 3C89 ?

A higher peak is observed around 03h UTC. This region of the sky contains many radio sources but trying to identify which one could be responsible for this fluctuation, we find two possible sources, named PKS0336-01 (2423mJy) and 3C89 (2200mJy).

Little peace of Catalogue of radio sources near 1420 MHz with information about PKS0336 and 3C89

Plot of detector data with unshadowed area around 05h Local or 03h UTC

Sky at 03h UTC on 7th Sep 2015

3° above Orion

Scanning some degrees above Orion we still receive radiation from 3C145 (M42), very faint but perceptible.

Transit of the area 3° above Orion

Sky on 7th Sept 2015 at 04h 40' UTC for RA 05h 57' DEC -2° 22' (Antenna Focus)

Milky Way transits

Following plots provide a view of the spectrum between 1420 and 1421 MHz The bottom X-axis contains the frequency values. The Y-axis shows the calculated signal power in decibel. The top X-axis shows the corresponding radial speed for every frequency value without correction. This correction should take into account the influence of several speed components coming from Earth rotation around own axis, earth rotation around the solar system barycenter and solar system rotation around our galaxy barycenter.

Around 5:50h UTC (7:50 Local) we detect the transit of the Milky Way by the galactic coordinates Lat 0° Long 214°.