SKA telescope gets its ‘1st fringes’

Here are the so-called “1st fringes” from 2 stations – each consisting of 256 antennas – in the part of the SKA telescope being built in Australia. The “1st fringes” for a radio telescope such as SKA is like 1st light for an optical telescope. It’s a new telescope’s 1st observation. What you see in these images is an interference pattern signal, as 2 of the SKA-Low stations peer toward the giant radio galaxy Centaurus A. Image via SKA Observatory.

• The SKA Observatory, an Earth-spanning radio observatory, is currently being built at two sites. One site is in South Africa (SKA-Mid), the other is in Australia (SKA-Low).
• The Australia site successfully connected two of its finished “stations” (256 radio telescopes each) to observe together for the first time, SKAO reported on September 17, 2024.
• These so-called “first fringes” are a large milestone in a radio telescope’s life and work. They’re equivalent to an optical observatory’s “first light.”

1st “light” for SKA telescope

Radio astronomers are thrilled about the Square Kilometer Array (SKA) telescopes, currently under construction at two sites, one in Australia and one in South Africa. The South Africa site will host 197 dish-type antennas. The Australian site (SKA-Low) has a different type of antenna, measuring at lower wavelengths. SKA-Low will ultimately have 131,072 antennas, divided into 512 “stations.” On September 17, 2024, the SKA-Low reported its first interferometric observations – a technique using the interference of radio waves to extract information – between two of its stations. This observation is that site’s so-called “first fringes,” equivalent to an optical telescope’s first light.

Indeed, it’s such a momentous event in the life of a radio telescope that SKA Observatory director-general Philip Diamond said:

This is the day that the SKA Observatory as a scientific facility was born.

The SKA-Low antennas in Australia resemble silvery Christmas trees and measure at longer wavelengths than the more familiar dish-style antennas in South Africa. They are collected in circular stations harboring 512 antennas each. On September 17, 2024, 2 such stations observed together, successfully forming an interferometer – a telescope of several connected antennas – for the first time. Image via SKAO.

Light or fringes, the 1st images of a new instrument

Maybe you know that radio waves – at the far end of the electromagnetic spectrum – are longer than waves of visible light? That’s why radio astronomy benefits from very long baselines … long distances between coordinating antennas. The greater the distance between antennas, the more clearly the telescope can “see” in radio. And the more antennas, the more sensitive the telescopes are to faint signals. Since the 1990s, astronomers have been picturing and planning an extremely big and transformative radio interferometer, an observatory consisting of many and distant antennas. SKA is the answer to that long-held vision.

Radio telescopes like SKA don’t typically have a first-light image, as is common for optical telescopes. The concept of “first light” isn’t the same for radio telescopes, as their construction and first use is more incremental.

But when two (or more) radio antennas – or stations of antennas as in the case of SKA-Low – are observing together for the first time, radio astronomers call this “first fringes” instead of first light. This name refers to the wavy signal that varies in time and frequency, correlated between the antennas in the telescope when they first observe together.

A SKA telescope milestone

George Heald, SKA-Low Lead Commissioning Scientist, explained why radio astronomers are especially excited about this achievement:

Finding a strong correlated signal between our first two SKA-Low stations means that the instrument can now function as a radio interferometer. This is an incredible milestone, one that has been achieved by the work of hundreds of people over many years. Many astronomers, including myself, are so excited for what comes next as this telescope continues to scale.

But for a radio observatory, there is not just one milestone before the observatory is fully ready for use. The SKA-Low first fringes come roughly half a year after the first antennas were installed at Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory (this is the full name of SKA-Low), in March 2024. In August this year, the first image from a single SKA-Low station was released, in a 24-hour observation of the southern sky.

The first SKA-Low station image was a 24-hour observation of the southern sky. It shows our Milky Way galaxy moving across the sky (as the Earth rotates). The annotated radio sources are other galaxies, and during the day, the sun is visible. One of the benefits of radio is that you can also observe during daytime. Video via SKAO.

Meanwhile, in South Africa

The South African site in Karoo has its own milestones. The assembly of the first actual dish of SKA-Mid took place on July 4, 2024. But on January 25, 2023, the SKA Observatory reported that its prototype telescope at Karoo – called SKAMPI – achieved first light with an image of the southern sky in radio.

Actual interferometry “first fringes” are yet to arrive for this part of the observatory, unless you count MeerKAT, which has been up and running for many years already and is going to be incorporated into the SKA-Mid.

You can see how it is not easy to pinpoint an actual “first light” moment for a radio observatory, with all the intricacies in its construction going on!

A prototype antenna for the giant SKA telescope array has released this 1st light image. It’s aimed toward the southern sky in the 2.5 GHz part of the radio end of the electromagnetic spectrum. The full oval (including the gray part) is the complete sky with the Milky Way galactic center in the middle. The radio emission to the right shows the part of the sky – featuring our Milky Way galaxy as a bright line – that the telescope can observe from South Africa. Image via the prototype (SKAMPI) team/ SKAO.

Radio astronomy arrays get better resolution

In radio astronomy, combining many telescopes into an interferometric array increases the resolution. In short, the larger the telescope, the better the resolution, but practical constraints make it impossible to build a single dish that large. The Chinese FAST is currently the world’s largest single-dish telescope at 500 meters (1640 feet). An array has the resolution of a virtual telescope as large as the longest distance between the antennas. In the case of SKAO, this translates to one telescope dish 150 km (93 miles) in diameter, instead of the 15 m (50 feet) of each individual antenna.

Three decades of planning into fruition

The Square Kilometre Array idea was first conceived in the early 1990s. It evolved into an intergovernmental organisation in 2021 – the 2nd astronomical one after European Southern Observatory (ESO) – and currently consists of nine member countries. In December 2022, SKAO held groundbreaking ceremonies at both of its observatory sites and started the construction in earnest.

A first light image of the full observatory will likely be hard to pinpoint, as the antennas will start being used as they are constructed. But, if the science from MeerKAT, the precursor observatory located at the same site, is an indication, we can likely expect some exceptional science to drop in as this radio facility keeps increasing in size. By the way, the 64 MeerKAT antennas will be incorporated into the final SKA, and SKAMPI is contributing to the development of the rest of the antennas.

Two sites with different SKA telescope antennas

Why build such a large observatory? What can we expect radio waves to reveal that we can’t see in, say, infrared with the Webb? The 197 antennas in South Africa, called the SKA-Mid, will observe from 350 MHz to 15.4 GHz in frequency. The Australian portion of the observatory, SKA-Low, will, as the name implies, observe at lower frequencies, from 50-350 MHz. Together, they will have a large collecting area, increasing the sensitivity by 10-100 times that of current observatories. The Australian telescopes are quite different in structure and looks. They are dipole antennas that mostly resemble Christmas trees and there will be roughly 131,000 of them, collected in 512 stations.

Science goals

In terms of science, this translates to being able to reach as far back as to the epoch of reionization, when stars and galaxies started forming. Only radio telescopes can measure neutral hydrogen far out in space, and, with the new ability to measure faint signals, can trace this building block of matter to before stars ionized the gas in the early universe.

And there are many more goals. The telescopes will better chart galaxy evolution, dark matter, and how the strength of dark energy has grown over time. They will monitor gravitational waves via observations of fluctuations in pulsar emission. SETI scientists will listen for faint signals indicating advanced life, while other exoplanet scientists will scrutinize the birth of stars and planets.

Other mysteries we want to learn (much) more about include black holes and fast radio bursts, not to forget more “local” astronomy where, for example, the telescopes trace neutral hydrogen gas in our own galaxy. There is a lot more to discover at home as well! But maybe the most exciting discoveries to come are the ones we do not know about yet. They can be expected, because for every new instrument that comes into use there have been surprises.

Bottom line: SKA-Low, the Australian part of the two SKA telescopes making up the SKA Observatory, successfully measured a correlated signal using two of its stations. Radio astronomers call such a measurement “first fringes” and it is a milestone in the construction of the new radio observatory.

Via SKAO

The post SKA telescope gets its ‘1st fringes’ first appeared on EarthSky.

from EarthSky https://ift.tt/9Gm63eJ

Here are the so-called “1st fringes” from 2 stations – each consisting of 256 antennas – in the part of the SKA telescope being built in Australia. The “1st fringes” for a radio telescope such as SKA is like 1st light for an optical telescope. It’s a new telescope’s 1st observation. What you see in these images is an interference pattern signal, as 2 of the SKA-Low stations peer toward the giant radio galaxy Centaurus A. Image via SKA Observatory.

• The SKA Observatory, an Earth-spanning radio observatory, is currently being built at two sites. One site is in South Africa (SKA-Mid), the other is in Australia (SKA-Low).
• The Australia site successfully connected two of its finished “stations” (256 radio telescopes each) to observe together for the first time, SKAO reported on September 17, 2024.
• These so-called “first fringes” are a large milestone in a radio telescope’s life and work. They’re equivalent to an optical observatory’s “first light.”

1st “light” for SKA telescope

Radio astronomers are thrilled about the Square Kilometer Array (SKA) telescopes, currently under construction at two sites, one in Australia and one in South Africa. The South Africa site will host 197 dish-type antennas. The Australian site (SKA-Low) has a different type of antenna, measuring at lower wavelengths. SKA-Low will ultimately have 131,072 antennas, divided into 512 “stations.” On September 17, 2024, the SKA-Low reported its first interferometric observations – a technique using the interference of radio waves to extract information – between two of its stations. This observation is that site’s so-called “first fringes,” equivalent to an optical telescope’s first light.

Indeed, it’s such a momentous event in the life of a radio telescope that SKA Observatory director-general Philip Diamond said:

This is the day that the SKA Observatory as a scientific facility was born.

The SKA-Low antennas in Australia resemble silvery Christmas trees and measure at longer wavelengths than the more familiar dish-style antennas in South Africa. They are collected in circular stations harboring 512 antennas each. On September 17, 2024, 2 such stations observed together, successfully forming an interferometer – a telescope of several connected antennas – for the first time. Image via SKAO.

Light or fringes, the 1st images of a new instrument

Maybe you know that radio waves – at the far end of the electromagnetic spectrum – are longer than waves of visible light? That’s why radio astronomy benefits from very long baselines … long distances between coordinating antennas. The greater the distance between antennas, the more clearly the telescope can “see” in radio. And the more antennas, the more sensitive the telescopes are to faint signals. Since the 1990s, astronomers have been picturing and planning an extremely big and transformative radio interferometer, an observatory consisting of many and distant antennas. SKA is the answer to that long-held vision.

Radio telescopes like SKA don’t typically have a first-light image, as is common for optical telescopes. The concept of “first light” isn’t the same for radio telescopes, as their construction and first use is more incremental.

But when two (or more) radio antennas – or stations of antennas as in the case of SKA-Low – are observing together for the first time, radio astronomers call this “first fringes” instead of first light. This name refers to the wavy signal that varies in time and frequency, correlated between the antennas in the telescope when they first observe together.

A SKA telescope milestone

George Heald, SKA-Low Lead Commissioning Scientist, explained why radio astronomers are especially excited about this achievement:

Finding a strong correlated signal between our first two SKA-Low stations means that the instrument can now function as a radio interferometer. This is an incredible milestone, one that has been achieved by the work of hundreds of people over many years. Many astronomers, including myself, are so excited for what comes next as this telescope continues to scale.

But for a radio observatory, there is not just one milestone before the observatory is fully ready for use. The SKA-Low first fringes come roughly half a year after the first antennas were installed at Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory (this is the full name of SKA-Low), in March 2024. In August this year, the first image from a single SKA-Low station was released, in a 24-hour observation of the southern sky.

The first SKA-Low station image was a 24-hour observation of the southern sky. It shows our Milky Way galaxy moving across the sky (as the Earth rotates). The annotated radio sources are other galaxies, and during the day, the sun is visible. One of the benefits of radio is that you can also observe during daytime. Video via SKAO.

Meanwhile, in South Africa

The South African site in Karoo has its own milestones. The assembly of the first actual dish of SKA-Mid took place on July 4, 2024. But on January 25, 2023, the SKA Observatory reported that its prototype telescope at Karoo – called SKAMPI – achieved first light with an image of the southern sky in radio.

Actual interferometry “first fringes” are yet to arrive for this part of the observatory, unless you count MeerKAT, which has been up and running for many years already and is going to be incorporated into the SKA-Mid.

You can see how it is not easy to pinpoint an actual “first light” moment for a radio observatory, with all the intricacies in its construction going on!

A prototype antenna for the giant SKA telescope array has released this 1st light image. It’s aimed toward the southern sky in the 2.5 GHz part of the radio end of the electromagnetic spectrum. The full oval (including the gray part) is the complete sky with the Milky Way galactic center in the middle. The radio emission to the right shows the part of the sky – featuring our Milky Way galaxy as a bright line – that the telescope can observe from South Africa. Image via the prototype (SKAMPI) team/ SKAO.

Radio astronomy arrays get better resolution

In radio astronomy, combining many telescopes into an interferometric array increases the resolution. In short, the larger the telescope, the better the resolution, but practical constraints make it impossible to build a single dish that large. The Chinese FAST is currently the world’s largest single-dish telescope at 500 meters (1640 feet). An array has the resolution of a virtual telescope as large as the longest distance between the antennas. In the case of SKAO, this translates to one telescope dish 150 km (93 miles) in diameter, instead of the 15 m (50 feet) of each individual antenna.

Three decades of planning into fruition

The Square Kilometre Array idea was first conceived in the early 1990s. It evolved into an intergovernmental organisation in 2021 – the 2nd astronomical one after European Southern Observatory (ESO) – and currently consists of nine member countries. In December 2022, SKAO held groundbreaking ceremonies at both of its observatory sites and started the construction in earnest.

A first light image of the full observatory will likely be hard to pinpoint, as the antennas will start being used as they are constructed. But, if the science from MeerKAT, the precursor observatory located at the same site, is an indication, we can likely expect some exceptional science to drop in as this radio facility keeps increasing in size. By the way, the 64 MeerKAT antennas will be incorporated into the final SKA, and SKAMPI is contributing to the development of the rest of the antennas.

Two sites with different SKA telescope antennas

Why build such a large observatory? What can we expect radio waves to reveal that we can’t see in, say, infrared with the Webb? The 197 antennas in South Africa, called the SKA-Mid, will observe from 350 MHz to 15.4 GHz in frequency. The Australian portion of the observatory, SKA-Low, will, as the name implies, observe at lower frequencies, from 50-350 MHz. Together, they will have a large collecting area, increasing the sensitivity by 10-100 times that of current observatories. The Australian telescopes are quite different in structure and looks. They are dipole antennas that mostly resemble Christmas trees and there will be roughly 131,000 of them, collected in 512 stations.

Science goals

In terms of science, this translates to being able to reach as far back as to the epoch of reionization, when stars and galaxies started forming. Only radio telescopes can measure neutral hydrogen far out in space, and, with the new ability to measure faint signals, can trace this building block of matter to before stars ionized the gas in the early universe.

And there are many more goals. The telescopes will better chart galaxy evolution, dark matter, and how the strength of dark energy has grown over time. They will monitor gravitational waves via observations of fluctuations in pulsar emission. SETI scientists will listen for faint signals indicating advanced life, while other exoplanet scientists will scrutinize the birth of stars and planets.

Other mysteries we want to learn (much) more about include black holes and fast radio bursts, not to forget more “local” astronomy where, for example, the telescopes trace neutral hydrogen gas in our own galaxy. There is a lot more to discover at home as well! But maybe the most exciting discoveries to come are the ones we do not know about yet. They can be expected, because for every new instrument that comes into use there have been surprises.

Bottom line: SKA-Low, the Australian part of the two SKA telescopes making up the SKA Observatory, successfully measured a correlated signal using two of its stations. Radio astronomers call such a measurement “first fringes” and it is a milestone in the construction of the new radio observatory.

Via SKAO

The post SKA telescope gets its ‘1st fringes’ first appeared on EarthSky.

from EarthSky https://ift.tt/9Gm63eJ