Fw: Re: [SARA] GRB Question

[Robert Fritzius]

Forwarded with permission. Note on names below: Fishman was NASA's PI on the Burst and Transient Source Experiment (BATSE) aboard the Compton Gamma-Ray Observatory.  Lestrade was a BATSE team member. -- On Fri, 5/17/13, John Patrick Lestrade <jp...@msstate.edu> wrote: From: John Patrick Lestrade <jp...@msstate.edu> Subject: Re: [SARA] GRB Question To: "Robert Fritzius" <frit...@bellsouth.net> Date: Friday, May 17, 2013, 10:02 PM Bob, The following may be germane to your recent query. For a short while Jerry Fishman and I were interested in the effect that some nearby GRB's seemed to have on the ionosphere. For ELF (extremely low frequency radio waves), like the kind that submarines use to "phone home", and which have wavelengths like 1000 km long, the effect of a grb blast was to cause a glitch in the phase of the radio waves. This is because the surface of the Earth and the ionosphere form a waveguide for these ELF. They bounce around the Earth like between two mirrors. The sudden compression of the ionosphere caused the glitch in the reflected wave. We looked at some data from the large Rugby antenna array (which I have visited and which is now torn down!). If memory serves there was a paper written about this effect, but I do not remember the authors. Patrick

[Robert Fritzius]

All, Correction to earlier post. (Lestrade concurs.) Most of you know already that submarines don't use VLF or ELF to "phone home." For them either frequency range is a "receive only" operation. Bob F.  --- On Sat, 5/18/13, Robert Fritzius <frit...@bellsouth.net> wrote:

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[Den Koawl]

Bob Hi,

 

Good information, Tnx......... so it is possible that these odd up / down spikes are not the GRB itself ( which i didnt think ) but the reaction of the ionosphere to pressure being forced on it. ?

 

Den

[Marcus D. Leech]

> Bob Hi,
> Good information, Tnx......... so it is possible that these odd up /
> down spikes are not the GRB itself ( which i didnt think ) but the
> reaction of the ionosphere to pressure being forced on it. ?
> Den
>

Those types of detector responses are usually due to an out-of-band
strong signal driving the front end the receiver into compression, and then
when it "lets go", your filter response on the detector tends to
produce that "bounce" type response.

I've seen that with aircraft radar altimeters at C-band.


--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

[Robert Fritzius]

Den, When I saw those "odd" up-down spikes first time, I didn't like them! (I was chasing a different rabbit.  Was expecting two "up" spikes (or two "down' spikes.) You go with what you have. You could be very well on the right track. I now like the spikes you have. Bob F. --- On Sat, 5/18/13, Den Koawl <dko...@gmail.com> wrote:

[Den Koawl]

Ok Bob, I find this interesting in that, i havent been able to match one of these double spikes to the exact time of a GRB event, which i guess makes some sense due to the fact i have been looking at the SWIFT page and seeing when SWIFT ddetects an event........... I have had a ffew come close but every one of my spikes occurs as much as some minutes or more after the SWIFT time and i have a few which occured on a day when SWIFT does not show any event...... Hmmmm.....

 

Den

[David Fields]

Hi Den,
I agree with Bob -- your double spikes may be the RF tail of the GRBs.  If they were the atmospheric (Compton scattering) respons to GRBs, then they would be seen almost immediately. The thing to do is to see how they correlate with SWIFT GRB data. SWIFT gets about 80 events per year but of course misses some of them (maybe the satellite is behind the earth's ionosphere, and has different sensitivites in different directions).  The BAT detector on SWIFT is (I think) what registers the first detection and BAT watches less than 0.1 of the sky at high sensitivity.  But I think that there are other ways of triggering SWIFT than just BAT.

Your receiver (what frequency and equipment?) watches less than half of the sky for all but the largest events. You can use a planetarium program and see if you were watching the proper direction when SWIFT registered a GRB, which would show why you might not observe the RF pulse.   I hope that this doesn't sound too complicated -- if you'll tell me your location then I will work out and tell you what are the 'overhead' coordinates for a few times of interest, for your loction.

You also might want to see how many of the 'biggest' SWIFT events showed up (some are below).  Especially check March 28, 2011, for SwiftJ1644+57, which may have been detected by a kid in Huntsville with a geiger counter.  If you want to write this up with him then I can put you in touch.
(more on this event, from Wiki entry, with some useful links) [March 28, 2011: Swift detected GRB 110328A, which subsequent analysis showed to possibly be the signature of a star being disrupted by a black hole or the ignition of an active galactic nucleus.^[19]"This is truly different from any explosive event we have seen before," said Joshua Bloom of the University of California at Berkeley, the lead author of the study published in the June issue of Science.[20

(good summary reference) http://www.cosmosmagazine.com/news/black-hole-eats-star-produce-gamma-ray-flash/
(good science writeup) http://en.wikipedia.org/wiki/GRB_110328A

Cheers,
David Fields
.....

• March 19, 2008: Swift detected GRB 080319B, a burst of gamma rays amongst the brightest celestial objects ever witnessed. At 7.5 billion light-years, Swift established a new record for the farthest object (briefly) visible to the naked eye. It was also said to be 2.5 million times intrinsically brighter than the previous brightest accepted supernova (SN 2005ap). Swift observed a record four GRBs that day, which also coincided with the death of noted science-fiction writer Arthur C. Clarke.^[13]

• September 16 and 17, 2012, "BAT triggered multiple times on a previously unknown hard X-ray source a few degrees from the Galactic Center. The trigger marked the onset of a dramatic transition from the low/hard to the high/soft state of the X-ray Nova “Sw J1745-26”, revealing a previously unknown black hole in our galaxy."^[10]

• April 24, 2013, Swift detected an X-ray flare from the Galactic Center. This proved not to be related to Sgr A* but to a previously unsuspected magnetar. Later observations by the NuSTAR and the Chandra X-Ray Observatory confirmed the detection.^[21]

• April 27, 2013, Swift detected the "shockingly bright" Gamma-ray burst GRB 130427A. Observed simultaneously by the Fermi Gamma-ray Space Telescope, it is one of the five closets GRBs detected and one of the brightest seen by either space telescope.^[22]

[Tom Crowley]

Current thinking by the Pros is that only 30% of the GRBs may be detected in radio.  Here is a presentation discussing this view:

 

http://www.asa2012.phys.unsw.edu.au/pdfs/Paul_Hancock_ASA_July2012_talk.pdf

 

Expected GRBs in SN afterglow.  This paper is interesting, it appears almost all 99+% are detected at sometime after the SN has light has reached Earth, kind of an poor way to word it.  Just can’t find a better way.  In any case most all are found several days after the light has reached Earth and in the case of Type 2s, it’s possible for the SN to remain bright for well over a year.  I’ve been caught with 2 that are almost at detection brightness 12-14 months later.  

 

http://iopscience.iop.org/0004-637X/508/2/760/fulltext/38226.text.html

 

In any case detecting and correlating GRBs to radio detection is a non-trivial task.

 

Tom Crowley

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[Den Koawl]

David Hi, i am running the SDR-IQ from RFSpace with SpectraVue software and the frequency is 24 kc, NAA ...... monitoring for SID. I am using a 1 meter loop antenna at present. I have used a dipole and and actually get a few dB higher signal strength, but the loop seems to be sufficient.

 

The location here is: 65 15 48 N    - 166 21 49

 

I am very near the Arctic Circle. I have only been noticing this since Feb 2013 when i started to monitor SID, so i dont have a lot of data yet, but since then i have 5 charts which I have marked this type of observation.

 

Den

[Den Koawl]

Tom Hi, interesting because all of these spikes occured later than what SWIFT showed for a detection, in fact a day or more later. Or possibly as another has mentioned that i may have detected something that SWIFT didnt. I dont have a lot of data yet on these since i have only noticed this since Feb of this year, and i dont have any data saved prior to that.

 

Can a GRB be detected at 1420 ? i hope to get my Dish back up this summer.

 

Den

[Den Koawl]

David Hi,

 

 i am running the SDR-IQ from RFSpace with SpectraVue software and the frequency is 24 kc, NAA ...... monitoring for SID. I am using a 1 meter loop antenna at present. I have used a dipole and and actually get a few dB higher signal strength, but the loop seems to be sufficient.

The location here is: 65 15 48 N - 166 21 49    Teller, Alaska

I am very near the Arctic Circle. I have only been noticing this since Feb 2013 when i started to monitor SID, so i dont have a lot of data yet, but since then i have 5 charts which I have marked this type of observation. After digging through my latest chart and checking for other observasions, i found something interesting today..... my 24 hr scan showed two different spikes, but very close to another observasion. ( See Attached File )..... I copied my plot and cut out all but the area of interest.

 

Den

On Sun, May 19, 2013 at 5:53 AM, David Fields <fiel...@aol.com> wrote:

[Arto Oksanen]

Hi Den,

Is there wrong date on your timestamps? Time in UTC? Is this today or May 18 as the GRB 130518A?

arto

2013/5/20 Den Koawl <dko...@gmail.com>

--
Arto Oksanen
arto.o...@jklsirius.fi
Muurame, Finland

"In a world where I feel so small, I can't stop thinking big."

[David Fields]

Hi Den,
If I read your plot and notes correctly, that's a very nice correspondence. Congratulations!

I'm wondering if you were able to reject noise better with your RFSpace rig, or perhaps do baseline averaging to maintain a reference value, than with other receivers.  Did you tune the loop and is it wound with 100m long wire?  I enjoy your polar location because you more or less observe the same celestial hemisphere at all times -- you don't have to always do the Ra/Dec calculation.  Is there some old date information hiding in your display (15/3/2012).

Cheers,
David

[Den Koawl]

Arto Hi, yes the date stamps are wrong in Excel, i cant get it to change..... the time stamps seem to be off near the end of the plot. The time / date stamps are good in the SpectraVue software, but everything goes out of wack in the Excel graph..... the csv file from the software doesnt seem to want to match up in Excel....... and i havent been able to correct it.

 

Den

[Den Koawl]

Tnx David. Well the Rcvr has some amount of adjustable filtering, and i have played with it and it is difficult to remove all the statics that it is picking up. I am getting the VLF pkg from RAS supply and im hoping it has the Spectra Cyber software with it, maybe i can get better results with that.

 

Yes the date stamp on the chart is wrong, i cant get it to change... it is an Excel graph, and although the SpectraVue software generates a csv file it is not quite compatible with Excel for some reason, and i dont know how to fix it. Time is ok, except towards the end of the chart i have notice the time being off as much as 20 minutes. So in other words, if i see a SID event at 2100...... the correct time would be 2040. The SpectraVue screen however seems to be right on, almost to the minute with GOES satellite..... usually, but not always when i see the trace starting up, i look at the GOES 6 hr 1 minute plot and im right on time. Interesting.......

 

The loop is wound with the length of wire i got when i ordered the SuperSID, i cant remember now what it was, i think about 120 meter of wire. Havent had no luck with the SuperSID device, it just shows a wild trace..... i love software tho and maybe that will work with this RAS VLF rcvr im getting. Other than that, if have to i could did out the old tube rcvr and run it plus have the benefit of the extra heat !  :-))  Yes the Polar region does offer a unique perspective for RA, and I am very much awaiting to see what happens after the coming ISON comet gives us a dusting........  i have read that it should create a nice aurora like event in our night sky which by Jan we will be in our 24 hr darkness period.

 

Ok, Tnx,

 

Den

[David Fields]

Hi Den,
I think that your VLF pkg will be a good one for monitoring 40kHz.  Spectra Cyber software is more specialized, and drives a software-tunable receiver that scans across the 1420 MHz hydrogen spinflip line. Of course, there may be some new features.

Please get your camera ready to share aurora photos when events occur.  You have the responsibility to do this for us!
Cheers,
David

[Den Koawl]

Yes i tried to some fotos about 2 weeks ago of a very nice auroral display...... which also made some humps on my chart ....... but when i loaded the fotos into the pc i got black screens..... i dont think its the right camera for the job. From what read this blue display that may occur as a result of the comet dust will only be visible from the polar regions..... so i really would like to get some fotos to share. With that please note their is also a live web cam in Fairbanks, AK which captures auroral displays.... might be an option for folks, i cant find the link at the moment, but i will try and then post it on here so Folks can check it out ..... in the fall of course when the darkness returns !

 

Ok on the VLF pkg,, the specs say it covers 10 to 40 kc, and works with 3 different types of software. I am going to try the SuperSID software since it is so easy to use, captures the data and generates the plots. Spectrumlab can also be used and the specs mention the Spectra Cyber software...... not sure what other software it will work with. But i need something else to try and eliminate the Excel graphing if possible so i can get more accurate Date / Time stamping on the plots.

 

Also i have my dish repaired but have to wait for better weather to get the neighbor boys over here to put it up for me, then i will be able to start monitoring at 1420 MHz.

 

73 & Tnx,

Den

[Den Koawl]

Yes the time is UTC and the plot is for 130518, the day of the event.

 

Den

On Mon, May 20, 2013 at 3:47 AM, Arto Oksanen <arto.o...@jklsirius.fi> wrote: