Sgr A* radio signal anyone?

Gentlemen,

Does anyone have any references which depict the radio signal emitted by Sgr A*
(center of the Milky Way) as a function of the time domain?

I've googled for several hours for Sgr A* and could only find static diagrams of
the source.

What I am looking for is the actual GRAPH of the source's signal as a function
of time, presumably bounded in some specific measured time domain, [t1, t2], the
time window used to graph the source's behavior.

Many thanks in advance,
--
Ioannis --- "There's _always_ a mistake, somewhere."

On May 4, 5:38*pm, "I.N. Galidakis" wrote:
Gentlemen,

Does anyone have any references which depict the radio signal emitted by Sgr A*
(center of the Milky Way) as a function of the time domain?

I've googled for several hours for Sgr A* and could only find static diagrams of
the source.

What I am looking for is the actual GRAPH of the source's signal as a function
of time, presumably bounded in some specific measured time domain, [t1, t2], the
time window used to graph the source's behavior.

Perhaps Macquart & Bower (2006) Astrophys.J. 641 302 would suit your
needs.

The place to look is NASA ADS and arxiv.org. The Macquart & Bower
paper is also availble for free on arxiv, with a link to a higher
resolution version.

Craig

On May 4, 3:38*pm, "I.N. Galidakis" wrote:
Gentlemen,

Does anyone have any references which depict the radio signal emitted by Sgr A*
(center of the Milky Way) as a function of the time domain?

I've googled for several hours for Sgr A* and could only find static diagrams of
the source.

What I am looking for is the actual GRAPH of the source's signal as a function
of time, presumably bounded in some specific measured time domain, [t1, t2], the
time window used to graph the source's behavior.

Many thanks in advance,
--
Ioannis --- "There's _always_ a mistake, somewhere."

Google never gives you what one is looking for. The only thing in
Google coming up
on Uma Thurman is her and her stalker. Stalk stalk stalk, everything
you ever wanted
to know about stalking, use Google.

On May 5, 12:28*am, gb wrote:
On May 4, 3:38*pm, "I.N. Galidakis" wrote:

Gentlemen,

Does anyone have any references which depict the radio signal emitted by Sgr A*
(center of the Milky Way) as a function of the time domain?

I've googled for several hours for Sgr A* and could only find static diagrams of
the source.

What I am looking for is the actual GRAPH of the source's signal as a function
of time, presumably bounded in some specific measured time domain, [t1, t2], the
time window used to graph the source's behavior.

Many thanks in advance,
--
Ioannis --- "There's _always_ a mistake, somewhere."

Google never gives you what one is looking for. The only thing in
Google coming up
on Uma Thurman is her and her stalker. Stalk stalk stalk, everything
you ever wanted
to know about stalking, use Google.

Google likes stalking stories. They put a high rating to such words
themselves so they
remain top search items for decades. Stalking to them means
collecting, the word
stalk translates to them that way. I switched to Yahoo, 30 percent
improvement
in to the point searches and in life. Long live Google and CCTV and
the deep recession
world of hours of searches on Google. Those who use Google do that.

On May 5, 12:34*am, gb wrote:
On May 5, 12:28*am, gb wrote:





On May 4, 3:38*pm, "I.N. Galidakis" wrote:

Gentlemen,

Does anyone have any references which depict the radio signal emitted by Sgr A*
(center of the Milky Way) as a function of the time domain?

I've googled for several hours for Sgr A* and could only find static diagrams of
the source.

What I am looking for is the actual GRAPH of the source's signal as a function
of time, presumably bounded in some specific measured time domain, [t1, t2], the
time window used to graph the source's behavior.

Many thanks in advance,
--
Ioannis --- "There's _always_ a mistake, somewhere."

Google never gives you what one is looking for. The only thing in
Google coming up
on Uma Thurman is her and her stalker. Stalk stalk stalk, everything
you ever wanted
to know about stalking, use Google.

Google likes stalking stories. They put a high rating to such words
themselves so they
remain top search items for decades. Stalking to them means
collecting, the word
stalk translates to them that way. I switched to Yahoo, 30 percent
improvement
in to the point searches and in life. Long live Google and CCTV and
the deep recession
world of hours of searches on Google. Those who use Google do that.

Think about it. Uma Thurman and her stalker is a five year old news,
and she had tons of news since. But the only thing that comes up
on Google on Uma Thurman is 'Uma Thurman and her stalker'.
You read what Google thinks is the stuff, you read what Google
likes you to read. They dominate, every intelligent person knows
that. You are stuck with the first 5000 labeled stories, which
is not dated stuff, but Google stuff of labeled stuff stuff.

I.N. Galidakis wrote:
Gentlemen,

Does anyone have any references which depict the radio signal emitted by Sgr A*
(center of the Milky Way) as a function of the time domain?

I've googled for several hours for Sgr A* and could only find static diagrams of
the source.

Google isn't very good at searching the primary literature.

ADS abstracts or arXiv are much better bets. Although even there you are
unlikely to find the raw data, rather some interpretation of the more
interesting bits out of long runs of boring sameness.

Try ADS:
http://adsabs.harvard.edu/cgi-bin/nph-basic_connect?qsearch=sgr+a+time+resolved+radio&ve rsion=1

ADS seem to have "improved" their user interface too.
It is now clunkier and much slower

What I am looking for is the actual GRAPH of the source's signal as a function
of time, presumably bounded in some specific measured time domain, [t1, t2], the
time window used to graph the source's behavior.

You will need to specify a waveband as well radio covers anything from
38MHz up to 30GHz in the various observing bands.

Many thanks in advance,

I can't see any obvious candidates to answer your question so my best
guess is that it doesn't vary all that much (at least not in a manner
that single dish radio telescopes can observe). If it did vary
significantly on an hourly timescale then the variability would spoil
aperture synthesis images of the galactic centre (and there are some
very good ones around). eg

http://rsd-www.nrl.navy.mil/7213/lazio/GC/

Regards,
Martin Brown

Craig Markwardt wrote:

On May 4, 5:38 pm, "I.N. Galidakis" wrote:
Gentlemen,

Does anyone have any references which depict the radio signal emitted by Sgr
A* (center of the Milky Way) as a function of the time domain?

I've googled for several hours for Sgr A* and could only find static
diagrams of the source.

What I am looking for is the actual GRAPH of the source's signal as a
function of time, presumably bounded in some specific measured time domain,
[t1, t2], the time window used to graph the source's behavior.

Perhaps Macquart & Bower (2006) Astrophys.J. 641 302 would suit your
needs.

The place to look is NASA ADS and arxiv.org. The Macquart & Bower
paper is also availble for free on arxiv, with a link to a higher
resolution version.

Exactly what I was looking for. Many thanks to all who replied.

Craig
--
Ioannis

Martin Brown wrote:
I.N. Galidakis wrote:
Gentlemen,

Does anyone have any references which depict the radio signal emitted by Sgr
A* (center of the Milky Way) as a function of the time domain?

I've googled for several hours for Sgr A* and could only find static
diagrams of the source.

Google isn't very good at searching the primary literature.

ADS abstracts or arXiv are much better bets. Although even there you are
unlikely to find the raw data, rather some interpretation of the more
interesting bits out of long runs of boring sameness.

Try ADS:

http://adsabs.harvard.edu/cgi-bin/np...+time+resolved
+radio&version=1

ADS seem to have "improved" their user interface too.
It is now clunkier and much slower

What I am looking for is the actual GRAPH of the source's signal as a
function of time, presumably bounded in some specific measured time domain,
[t1, t2], the time window used to graph the source's behavior.

You will need to specify a waveband as well radio covers anything from
38MHz up to 30GHz in the various observing bands.

Many thanks in advance,

I can't see any obvious candidates to answer your question so my best
guess is that it doesn't vary all that much (at least not in a manner
that single dish radio telescopes can observe). If it did vary
significantly on an hourly timescale then the variability would spoil
aperture synthesis images of the galactic centre (and there are some
very good ones around). eg

http://rsd-www.nrl.navy.mil/7213/lazio/GC/

I agree, and after consulting with the article, the article seems to agree with
you: There seems to be no "apparent" quasi-periodic behavior for a max deltaT of
200 days, according to the conclusion.

On the other hand, I don't know about you, but when I step out on a clear summer
night, one of the first things that my intelligent faculties are attracted to,
is the sheer IMMENSITY of the light signal from the Sagittarius region, as a
whole.

I am not sure I trust myself on this, but I find the simultaneous existence of
these two, somewhat contradictory:

A radio signal with total non-periodicity emanating from something so
unimaginably huge, that would be visible from any star system anywhere inside
it?

I am probably going crazy sooner than expected.

Many thanks,

Regards,
Martin Brown
--
Ioannis --- "There's _always_ a mistake, somewhere."

On May 5, 9:05*pm, "I.N. Galidakis" wrote:
I am not sure I trust myself on this, but I find the simultaneous existence of
these two, somewhat contradictory:

A radio signal with total non-periodicity emanating from something so
unimaginably huge, that would be visible from any star system anywhere inside
it?

Actually, in visible light Sgr A* is completely invisible. It is
detectable in radio and X-ray. Periodic emission doesn't really have
anything to do with "hugeness." In fact it's quite difficult for a
large thing to pulsate.

The Sagittarius region is so bright because that is the direction of
the galactic center, where most of the stars in the galaxy are
located.

CM

I.N. Galidakis wrote:
Martin Brown wrote:
I.N. Galidakis wrote:
Gentlemen,

Does anyone have any references which depict the radio signal emitted by Sgr
A* (center of the Milky Way) as a function of the time domain?

Google isn't very good at searching the primary literature.

ADS abstracts or arXiv are much better bets. Although even there you are
unlikely to find the raw data, rather some interpretation of the more
interesting bits out of long runs of boring sameness.

Try ADS:

http://adsabs.harvard.edu/cgi-bin/np...+time+resolved
+radio&version=1
ADS seem to have "improved" their user interface too.
It is now clunkier and much slower
What I am looking for is the actual GRAPH of the source's signal as a
function of time, presumably bounded in some specific measured time domain,
[t1, t2], the time window used to graph the source's behavior.
You will need to specify a waveband as well radio covers anything from
38MHz up to 30GHz in the various observing bands.
Many thanks in advance,

I can't see any obvious candidates to answer your question so my best
guess is that it doesn't vary all that much (at least not in a manner
that single dish radio telescopes can observe). If it did vary
significantly on an hourly timescale then the variability would spoil
aperture synthesis images of the galactic centre (and there are some
very good ones around). eg

http://rsd-www.nrl.navy.mil/7213/lazio/GC/

I agree, and after consulting with the article, the article seems to agree with
you: There seems to be no "apparent" quasi-periodic behavior for a max deltaT of
200 days, according to the conclusion.

That is sort of what I expected although it is always worth looking for
periodic behaviour.

On the other hand, I don't know about you, but when I step out on a clear summer
night, one of the first things that my intelligent faculties are attracted to,
is the sheer IMMENSITY of the light signal from the Sagittarius region, as a
whole.

Where I live it barely makes it over the horizon and extinction takes
away a fair proportion of the light. Cygnus looks good though. If I am
on holiday at lower latitudes with dark skies then I know what you mean.

I am not sure I trust myself on this, but I find the simultaneous existence of
these two, somewhat contradictory:

A radio signal with total non-periodicity emanating from something so
unimaginably huge, that would be visible from any star system anywhere inside
it?

I am probably going crazy sooner than expected.

A big area source tends not to change brightness quickly even if
individual components are varying independently. The surrounding
brightness makes it hard to detect changes in a faint point source.

A compact radio source tends to vary more rapidly. That is why you might
expect that the very compact black hole at the galactic centre would
show transient signals if you could isolate them from the rest of the
surrounding mush. I expect Chandra is the best bet for observing rapid
changes since it has both the resolution and penetrating power eg.

http://chandra.harvard.edu/photo/2001/0204flare/

I don't know if radio astronomers have looked at it when a transient
flare was known to be occurring from X-ray observations.

VLA snapshot mode ought to be able to do something along these lines.
But observations on the big scopes are scheduled months in advance I
don't known how easy it would be to divert to a target of opportunity
except during engineering time.

SS 433 is about the most studied of the candidate black hole/neutron
star with matter going down the gravitational well. eg

http://adsabs.harvard.edu/full/1991SvAL...17..258C

Plenty of observations of its periodicity in multiple wavebands. Same
for the cataclysmic variable stars (which amateurs help to monitor).

Regards,
Martin Brown