“NASA has scheduled a media teleconference Wednesday, May 14, at 1 p.m. EDT, to announce the discovery of an object in our Galaxy astronomers have been hunting for more than 50 years.”

Read more (http://www.nasa.gov/home/hqnews/2008/may/HQ_M08089_Chandra_Advisory.html)

Hrmm... X-rays and ground based observations. I'm thinking either black hole at the centre of the galaxy (Seyfert, 1940's), or dark matter annihilation within the galactic halo (Zwicky 1930's, Rubin 1970's), but those are only the obvious ones.

Hum,
could be,
but the word on the street says it's the identification of Type Ia Supernova progenitors.

Why are they being so secretive?

Suspense. If I remember correctly, they did the same thing for the Bullet Cluster dark matter lensing announcement a couple of years ago.

Why are they being so secretive?

Hum,
because it's a embargoed news story; and only a minor news story, of no interest to the general public.
Be prepared for the lack of coverage by the general media.

"The most recent supernova in our galaxy has been discovered by tracking the rapid expansion of its remains. This result, using NASA's Chandra X-ray Observatory and the National Radio Astronomy Observatory's Very Large Array, will help improve our understanding of how often supernovae explode in the Milky Way galaxy.
The supernova explosion occurred about 140 years ago, making it the most recent in the Milky Way. Previously, the last known supernova in our galaxy occurred around 1680, an estimate based on the expansion of its remnant, Cassiopeia A."

Read more (http://www.nasa.gov/home/hqnews/2008/may/HQ_08126_Chandra_Supernova.html)

Blobrana:

Thanks for the update.

A little problem with the way the article was written. It references that the supernova occurred 140 years ago. Impossible. It was detectable 140 years ago, but since it occurred in the center of the galaxy, it actually took place much further back in time, due to the great distance the light had to travel.

The Pierre Auger should not now find any relativistic high-E particles that were emitted, because we lost our 'window of opportunity' 140 years ago. However, if they go off at the rate of several per century in the galactic center, obscured by all that 'murk', then perhaps we might see some new ones going off in the next few years with the Pierre Auger, and alert us to examine via X-ray, etc. as for this one.

Also, wasn't the Cassiopeia A supernova observed visually in China and recorded as to the exact year? Or am I thinking of another one? Isn't that the 'Crab Nebula' these days?

In my experience astronomers often talk about events 'occuring' when the light reaches Earth, rather than when the light left the emitting object. That might be because the date of observation can be known accurately while the date of the event may never be known accurately.

Cassiopeia A is (obviously) in Cassiopeia; the light from that supernova would have reached Earth about 300 years ago, but was not observed for some reason. Perhaps it was hidden by previous shells of expelled matter.

The Crab Nebula is in Taurus, and light from that event was observed in 1054.

Two more visible supernovae have been seen since, one in 1572 by Tycho Brahe, and one in 1604 by Kepler. And of course there was the one in the LMC in 1987; my brother saw that one.

A little problem with the way the article was written. It references that the supernova occurred 140 years ago.

Yeah,
i would agree.
This is what the researchers originally published a while ago...

Title: The Youngest Galactic Supernova Remnant: G1.9+0.3
Authors: S.P. Reynolds, K.J. Borkowski, D.A. Green, U. Hwang, I. Harrus, R. Petre
(Version v2)

Our 50 ks Chandra observation of the small radio supernova remnant (SNR) G1.9+0.3 shows a complete shell structure with strong bilateral symmetry, about 100'' in diameter. The radio morphology is also shell-like, but only about 84'' in diameter, based on observations made in 1985. We attribute the size difference to expansion between 1985 and our Chandra observations of 2007. Expansion is confirmed in comparing radio images from 1985 and 2008. We deduce that G1.9+0.3 is of order 100 years old -- the youngest supernova remnant in the Galaxy. Based on a very high absorbing column density of 5.5 X 10^{22} cm^{-2}, we place G1.9+0.3 near the Galactic Centre, at a distance of about 8.5 kpc, where the mean remnant radius would be about 2 pc, and the required expansion speed about 14,000 km s^{-1}.
Not only is G1.9+0.3 the youngest known Galactic remnant, it is also only the fourth Galactic X-ray synchrotron-dominated shell supernova remnant.

Source (http://arxiv.org/PS_cache/arxiv/pdf/0803/0803.1487v2.pdf) (987kb, PDF)

Position(J2000): RA 17h 48m 45s Dec -27° 10' 00

Note that the object as observed today has the appearance of a remnant which is circa 140 years old, so in that respect it is reasonable to say that it has that age. The light-time-travel period can be ignored as far as the observations are concerned. In 100 years time we will be observing an object with an age of circa 240 years in this location.

Eburacum45:

Thanks for correcting me on my recollections. Yeah, that one a millenia ago is the one that was observed in China, but apparently not recorded in Europe [too much dark ages?!].

I'll try to get used to the astronomer-speak, though technically I find it somewhat confusing. I prefer direct astrophysics-speak.

Anyone want to wager whether the next supernova in the galactic center will be dectected by the Pierre Auger or other particulate radiation first, or by X-ray?