Summary

This is a report of a possible Gamma Ray Burst (GRB) observed by Radio Astronomy methods.

Background

Daily continuum observations have been in progress for several months using both the 406.7 MHz, 3.3-meter dish (UHF) and a 40 kHz system with an east/west antenna (VLF). A PC controls each system (UHF and VLF).

The data collection software and receivers are from Radio Astronomy Supplies (RAS). The PC clocks are synchronized each night at local midnight, when the new daily observations Que. are set. Sample rate for both UHF and VLF system was set at 1 sample every 5 seconds.

General Conditions

There were no storms near the observation location. The UHF system was set at an elevation of 65 degrees looking due south from my location in Grand Rapids Michigan. A second receiver, that checks the frequencies both above and below the 406.7 MHz frequency, was quite. A check was done of space weather to see if there were any reported events, there were none (see the web sight at: http://www.sec.noaa.gov/today.html).

Event Description

At about 11:53 local time I was working on software for the Beowulf cluster computer (on a different computer) when I noted a general rise in the UHF continuum, a check of possible source was done using Jim Sky’s Radio Sky Planetarium, no objects were in the radio telescopes beam. The event continued to grow in amplitude until local midnight, the system was down for about 90 seconds to switch the Que.’s and returned to observing the event. Several min. after local the event appeared to end. Near the end of the UHF event the VLF system started to display a SID (Sudden Ionosphere Disturbance), this lasted for several min.

Observatory Location: 42 Deg. 58 min. N
85 Deg. 40 min. W

Sky Location of UHF Beam: Dec = +18.23
RA = 17.67

Maximum Flux Density observed: ~ 500 Jy

Using Virgo A (3C274) as a reference source.

UHF Event Start Time: 11:53:08 EDT 03:53:08 UTC

UHF Event End Time: 12:08:58 EDT 04:08:58 UTC

UHF Event Length: ~16 min. 10 seconds

VLF Event Start Time: 12:06:04 EDT 04:06:04 UTC

VLF Event End Time: 12:15:39 EDT 04:15:39 UTC

VLF Event Length: ~9 min. 35 seconds

Summary

If the events are related and the VLF event is a true SID then we may have an observation of a GRB on 406.7 MHz. Dual frequency observation may be the key to finding GRB events on frequency.

James H. Van Prooyen

Data Plots

Listed below are plots of the events, the first plot is the start of the UHF event the second plot is the end of the UHF event, the third plot is the VLF event.

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Will n Company 2004