D-RAP and Gamma Ray Bursts

[hamateur 1953]

That GRB of last year got me thinking about D-RAP.   I actually use it as a “ heads up” so to speak of large or persistent solar activity.  I would think A GRB should show on D-RAP however briefly, but as far as I am aware its main purpose is ionospheric monitoring. Anyone know more?? Tnx. Mike. 

[Newbie]

26 minutes ago, hamateur 1953 said:

That GRB of last year got me thinking about D-RAP.   I actually use it as a “ heads up” so to speak of large or persistent solar activity.  I would think A GRB should show on D-RAP however briefly, but as far as I am aware its main purpose is ionospheric monitoring. Anyone know more?? Tnx. Mike. 

 

Interesting question @hamateur 1953 

The first article explains the technology behind D-rap detection of Solar X-Rays .

Gamma rays are much more energetic and are detected by spectrometry and photometers and also by the more difficult task of gamma ray imaging.

These are outlined in the second article.

N.

https://imagine.gsfc.nasa.gov/observatories/technology/gammaray_detectors1.html#

https://www.swpc.noaa.gov/content/global-d-region-absorption-prediction-documentation

 

[helios]

Coincidentally, there was a very bright GRB yesterday evening:
https://gcn.nasa.gov/circulars/35221


Another question would be, if the GOES/ACE satellites could detect such short events. 
The EPAM chart doesn't show anything in this energy range:


The energy doesn't seem to have been exceeding much above 1 MeV, so it would be below the GOES proton channels, which are used for D-RAP.
https://grb.mpe.mpg.de/grb/GRB231129799/

Edited November 30, 2023 by helios

[hamateur 1953]

Very interesting, and that was what I was wondering.  Also since D-RAP is mainly concerned with our star, not wide-field so to speak, perhaps entire events even within its frequency ranges might be missed. Of course, this is only idle speculation on my part.  Thanks for weighing in @helios!

Obviously, myself  and others use D-RAP for its revelations on X radiation to our ionosphere primarily, but it’s also nice to know it also incorporates particle involvement as well to some degree.   I followed your link @helios No kidding that was bright!  Makes you wonder what either blew up, collapsed, or perhaps both!! 

Edited November 30, 2023 by hamateur 1953

[Philalethes]

I think that ideally a GRB that strong should show on D-RAP since it most likely caused similar levels of attenuation as an M-flare would have (not 100% sure about that though, maybe someone has more detailed information about it), but I don't think it actually does; if I'm not mistaken the D-RAP is essentially just a model that includes various parameters like Solar flares and doesn't actually monitor and reflect reality. The description says this, so maybe it's just those two parameters:

Quote

All of the components update continuously, driven by one-minute GOES X-ray flux data and by five-minute GOES proton flux data.

Looking at the D-RAP archive of that day it's at least clear that there's no sign of the GRB there, as all the minor and major disturbances during the relevant period are accounted for by the flaring on that day as seen here on SWL archive:

Since the declination of the event was just ~20° it would definitely have been visible there if the D-RAP had a more advanced form of live monitoring rather than just being a simple model based on X-ray flux and proton levels (again assuming that the GRB in fact did cause similar interference as a low-level M-flare).

 

I suppose the better question is: if the GRB had similar effects to a low-level M-flare as I've read a few times by now (although I haven't looked too much into it), why doesn't it show up on the GOES X-ray flux monitoring? Newbie mentions that gamma ray detection is something quite different, but if I'm not mistaken this burst occurred over a wide range of frequencies, and was detected by a lot of different X-ray imaging instruments; maybe the energy in that part of the spectrum was simply too low?

[helios]

Another thought:
While the GRB event is rather short (seconds), it's effect on the ionosphere can last for several minutes, because recombination takes time.
But the D-RAP model relies entirely on satellite data from X-rays and protons, not on ionospheric measurements.
So if the event is too short, it might not show up at all.

The strongest observed GRB so far (221009A) had an impact on the ionosphere comparable to a higher level C flare. This was derrived from indirect ionospheric measurements, from amplitude and phase anomalies of VLF signals.

I don't know yet how yesterdays GRB compares to this. But from reports and my own observations, there were no VLF anomalies observed. But it's location was also not above any typical VLF propagation path for me.

The goes-xray detectors are sort of narrow band, which might also limit the energy they receive. 1-8 Angstrom would correspond to 12.4-99.2 keV.

Edited November 30, 2023 by helios

[Philalethes]

Looks like I was brutally misled by my Google search for the date:

In reality the burst occurred the day before, so I guess the imagery above can be discarded. I did however check again for October 9, and there doesn't seem to be any sign of it there either on the X-ray flux monitoring (and thus not on the D-RAP system either). I briefly checked SDO imagery too to confirm that the low-level flaring we see was indeed from Solar activity, which checks out.

One things remains to be checked though, and that's where exactly the GRB was coming from relative to Earth at the time, because when I think about it there's not that much of a chance that it'd come from a direction aligned enough with Sol for the GOES instruments to pick it up. I've found the celestial coordinates, but I doubt it will be easy, if possible at all, to find any satellite that was measuring X-rays in that direction at the time.

In any case, that would explain why GOES doesn't pick it up, and thus why it's not included in the D-RAP. A possible solution for including such events in the D-RAP would be for it to include data from the X-ray imaging systems that pick up these events from all over the celestial sphere, and feed in the appropriate energy (assuming the energy in the X-ray range is indeed high enough to have a similar effect as flares).

[hamateur 1953]

I remember @KW2P and myself were both puzzled a few months or more back when it seemed to us that the D layer absorption levels were much higher than might be accounted for by normal C level X radiation. I think @Newbie or perhaps another made us aware that the D-RAP modeling had been upgraded to incorporate anticipated additional signal attenuation a few years back. 

Yes

On 11/30/2023 at 3:32 AM, helios said:

Another thought:
While the GRB event is rather short (seconds), it's effect on the ionosphere can last for several minutes, because recombination takes time.
But the D-RAP model relies entirely on satellite data from X-rays and protons, not on ionospheric measurements.
So if the event is too short, it might not show up at all.

The strongest observed GRB so far (221009A) had an impact on the ionosphere comparable to a higher level C flare. This was derrived from indirect ionospheric measurements, from amplitude and phase anomalies of VLF signals.

I don't know yet how yesterdays GRB compares to this. But from reports and my own observations, there were no VLF anomalies observed. But it's location was also not above any typical VLF propagation path for me.

The goes-xray detectors are sort of narrow band, which might also limit the energy they receive. 1-8 Angstrom would correspond to 12.4-99.2 keV.

I was aware of the modeling too. But wasn’t aware that VLF spherics were being incorporated also.  I think @Newbie practically caused me trauma awhile back trying to envision vlf waves from another perspective last year.  Haha. Cool stuff.   I misstated this.  For those few reading this. It is perhaps unlikely that vlf spherics are incorporated in the calculations of D-RAP. Mike. 

Edited December 1, 2023 by hamateur 1953
Reflections

[Newbie]

7 minutes ago, hamateur 1953 said:

I remember @KW2P and myself were both puzzled a few months or more back when it seemed to us that the D layer absorption levels were much higher than might be accounted for by normal C level X radiation. I think @Newbie or perhaps another made us aware that the D-RAP modeling had been upgraded to incorporate anticipated additional signal attenuation a few years back. 

Gamma  rays can be affected by D-layer absorption in the Earth's ionosphere. The D layer is known for attenuating high-frequency electromagnetic waves, including gamma rays, due to the presence of free electrons. This absorption phenomenon is an important consideration in various fields, including radio communication and space science.

The absorption of gamma rays in the D layer may not be explicitly represented on a standard ionospheric absorption graph, as these graphs often focus on radio frequency bands relevant to communication. However, the general principle of increased absorption in the D layer for higher frequencies applies to gamma rays as well. Specific gamma-ray absorption graphs exist for research purposes.

Typically they showcase the exponential decrease in intensity as gamma rays pass through matter. The material's thickness and density influence the absorption rate. The absorption coefficient (μ) is often plotted against the gamma-ray energy. This graph demonstrates how gamma rays lose intensity as they travel through a substance due to interactions such as photoelectric absorption, Compton scattering, and pair production. The specifics vary based on the material and energy range considered in the graph.

https://www.sciencedirect.com/topics/physics-and-astronomy/gamma-ray-absorption

33 minutes ago, helios said:

Another thought:
While the GRB event is rather short (seconds), it's effect on the ionosphere can last for several minutes, because recombination takes time.
But the D-RAP model relies entirely on satellite data from X-rays and protons, not on ionospheric measurements.
So if the event is too short, it might not show up at all.

The strongest observed GRB so far (221009A) had an impact on the ionosphere comparable to a higher level C flare. This was derrived from indirect ionospheric measurements, from amplitude and phase anomalies of VLF signals.

I don't know yet how yesterdays GRB compares to this. But from reports and my own observations, there were no VLF anomalies observed. But it's location was also not above any typical VLF propagation path for me.

The goes-xray detectors are sort of narrow band, which might also limit the energy they receive. 1-8 Angstrom would correspond to 12.4-99.2 keV.

The time period is indeed short and I would agree it may not show up at all on D - rap.

N.

[helios]

But I doubt that the D-RAP model would know the origin of the x-rays. I think it assumes that everything is coming from the sun (so, affecting only the sunlit side of the earth), which would not be accurate in this case.

[hamateur 1953]

Agreed. And outta likes yet again. Thanks fer replies guys and gal!! 

Edited November 30, 2023 by hamateur 1953

[Philalethes]

1 hour ago, helios said:

But I doubt that the D-RAP model would know the origin of the x-rays. I think it assumes that everything is coming from the sun (so, affecting only the sunlit side of the earth), which would not be accurate in this case.

Yep, that's what I concluded with as well, since it uses X-ray and proton flux values from GOES, so it's pretty much only based on what GOES measures.

Also, haven't looked into how powerful the burst was in the X-ray part of the spectrum yet, maybe I'll check if it's available anywhere later. If it were powerful enough then including such data into the model could be an idea, but then again it's so rare for such strong bursts to occur in the first place, so it's probably not worth the effort to integrate the data just for that.