Oct 3, 2023 07:09 PM
(This post was last modified: Oct 3, 2023 07:34 PM by C C.)
https://www.supercluster.com/editorial/t...ti-signals
INTRO (excerpts): Dashed hopes and false alarms are a way of life for SETI. And life is getting noisier, as SETI scientists battle against increasing radio frequency interference (RFI) while straining to hear any whispers from possible technological life elsewhere in the Universe.
[...] The prevalence of RFI means that SETI is picking up signals all the time. Usually, sophisticated algorithms are able to sift through the terabytes of data that are typically being collected by radio telescopes as they scan across billions of narrowband channels, and identify the terrestrial interference. When that fails, if the signal is still transmitting, then another simple check is a spatial one: if the signal is real, turning your telescope away from its apparent point of origin in the sky should have the effect of seeing the signal go away, to return when you point back at its source. If you can still hear the signal when turning your telescope off-target, then it must be local interference.
But every now and then a signal comes along that beats these filters. These false alarms can be a double-edged sword, says Seth Shostak.
“On the one hand, false alarms are kind of frustrating because you spend a lot of effort on them and you get people’s hopes up, but personally, if I had to vote, I’d say that false alarms are valuable because they test the system.”
For one thing, the detection of false alarms shows that your equipment is working. In SETI that’s not automatically obvious; unlike radio astronomers who know to expect a signal from neutral hydrogen if they point at a galaxy, SETI astronomers don’t expect to hear anything, at least not right away.
Identifying the origin of false alarms and the patterns they leave in the data allows the filters to recognize them in the future, making the search more efficient.
The most exciting false alarms also often have an interesting story to tell as they become part of the fabric of SETI’s own mythology. So without further ado, here are six of the best false alarms in SETI... (MORE - details)
COVERED: The Spy Plane in Project Ozma ..... A Signal from SOHO ..... Microwave Misunderstandings ..... The Alien Megastructure Star ..... BLC-1 ..... Beating the False Alarms (Wow! signal?)
INTRO (excerpts): Dashed hopes and false alarms are a way of life for SETI. And life is getting noisier, as SETI scientists battle against increasing radio frequency interference (RFI) while straining to hear any whispers from possible technological life elsewhere in the Universe.
[...] The prevalence of RFI means that SETI is picking up signals all the time. Usually, sophisticated algorithms are able to sift through the terabytes of data that are typically being collected by radio telescopes as they scan across billions of narrowband channels, and identify the terrestrial interference. When that fails, if the signal is still transmitting, then another simple check is a spatial one: if the signal is real, turning your telescope away from its apparent point of origin in the sky should have the effect of seeing the signal go away, to return when you point back at its source. If you can still hear the signal when turning your telescope off-target, then it must be local interference.
But every now and then a signal comes along that beats these filters. These false alarms can be a double-edged sword, says Seth Shostak.
“On the one hand, false alarms are kind of frustrating because you spend a lot of effort on them and you get people’s hopes up, but personally, if I had to vote, I’d say that false alarms are valuable because they test the system.”
For one thing, the detection of false alarms shows that your equipment is working. In SETI that’s not automatically obvious; unlike radio astronomers who know to expect a signal from neutral hydrogen if they point at a galaxy, SETI astronomers don’t expect to hear anything, at least not right away.
Identifying the origin of false alarms and the patterns they leave in the data allows the filters to recognize them in the future, making the search more efficient.
The most exciting false alarms also often have an interesting story to tell as they become part of the fabric of SETI’s own mythology. So without further ado, here are six of the best false alarms in SETI... (MORE - details)
COVERED: The Spy Plane in Project Ozma ..... A Signal from SOHO ..... Microwave Misunderstandings ..... The Alien Megastructure Star ..... BLC-1 ..... Beating the False Alarms (Wow! signal?)