Abstract: The results of the author’s radio meteor observations for December 2019 are presented, as well as the observing results of the meteor shower of the Geminids according to the Canadian Meteor Orbit Radar, (CMOR).
The observations were carried out at a private astronomical observatory near the town of Molodechno (Belarus) at the place of Polyani. A 5 element-antenna directed to the west was used, a car FM-receiver was connected to a laptop with as processor an Intel Atom CPU N2600 (1.6 GHz). The software to detect signals is Metan (author – Carol from Poland).
In the first week of December meteor activity was higher due to the combined activity of many minor streams, on top of the main Geminid meteor stream. The total activity with the Chi Orionids on December 2 reached about 45 signals per hour. The peak activity of the Geminids was recorded during 05h00m-07h00m UT on December 14, while the visual peak occurred around 23h40m UT on December 14 (according to imo.net). The difference in time can be explained by the difference in the observing methods. The Earth first encounters the smaller meteoroids (radio observations) and a bit later the larger particles being recorded visually. The second reason is the radiant reaching the optimal reflection geometry of the antenna’s directional pattern.
In the first half of the month, according to the recorded activity of CMOR (identification of on radar images) the following minor streams displayed activity: NOO, DPC, QUA, DGE, ZLE, DTH, HYD, ACA, DSA, DTA, DNA, DEL, DRV, DEC, ORN, DAD, DCC, KLI, SSE, ORS, GCM, RLE, MON, PUP, PHO, Chi Orionids, GEM, DMT. In the second half of the month there were less minor streams, so the total activity was less: MON, ACA, HYD, SSE, DHY, ORS, DLM, QUA, DMT, DMH, ALY, DLN, DCM, AHY, DDL, GEM, URS, COM. Noticeable activity around December 4 and 5 seems to confirm the activity of the meteor streams GEM and NOO (the total activity of these two showers was the same as that of the GEM stream alone in the period from December 9 to 11). Figure1 shows the maxima of minor meteor showers in black, medium activity showers in blue, variable activity showers in green and the major meteor shower in red.
The Geminid meteor shower has been detected on radar maps from November 23 onward. Confident identification of the shower occurs from November 24. However, according to IMO’s visual data, the meteor stream starts later – on December 4. On December 1, for the first time there was a noticeable “redness” of the radiant, i.e. the activity of the stream then became stable and evident. The discrepancy with my data can be explained by the higher sensitivity of the radar, which causes the peak activity to occur about 15 hours earlier. December 23 is the last date when the radiant of this stream is identified on radar maps. The shower activity ends around December 25th.
The SNR value determined by the MaximDL photometry software with correction modifications (R,Y,G) was used to determine the activity level. A manual search was performed to detect the most optimal SNR value. SNR values were obtained by moving the cursor over the radiant image on the radar maps. General formula for calculating the shower activity level :
SNRact = SNR1 + R + Y + G, where SNR1 is the total SNR level of the white and pink radiant area, R is the size in pixels of the radiation area on the radar maps, marked in red, Y is the size in pixels of the radiation area, marked in yellow on the radar maps, G is the size in pixels of the radiation area, marked in green on the radar maps.
According to the CMOR data, peak activity of the stream was kept at a high level during the period from 13 December 2019 around 01h00m UT to 14 December 2019 around 13h00m UT probable peak of activity of the stream occurred around 15h00m UT 13 December 2019.
I would like to thank Sergey Dubrovsky for the software they developed for data analysis and processing of radio observations. Thanks to Paul Roggemans for his help in the lay-out and the correction of this article.
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Rendtel Jurgen (2019). “Meteor Shower Calendar”. IMO.