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Mapping dots in the sky using radio astronomy

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Every week our observatory has a science meeting, which we can attend either in person or via Zoom. After hearing about the latest admin and project updates, we discuss the latest scientific activities and discoveries made by our scientists and engineers and their collaborators.

At a recent meeting, one astronomer presented her latest results in imaging an intriguing gas and dust structure in the sky. The image was peppered with lots of little dots, each of which was a distant galaxy. The image was obtained using a radio telescope and showed what we would see if our eyes could see radio waves.

Our ability to see detail in what we are looking at depends on the size of the lens forming the image compared with the wavelength of the light coming from what we are looking at. If our eyes are in good working order, we should be able to see details as small as about 1% of the area of the lunar disc.

Radio waves are electromagnetic waves, just like light. The only difference between them is the wavelengths (the distance between two wave crests) of radio waves are enormously greater. For example, yellow light has a wavelength of about 580 nanometres (a nanometre is a billionth of a metre). Radio waves have lengths ranging from maybe about a millimetre to hundreds or thousands of metres. The wavelength 21 cm is a very important one for radio astronomy, because emissions at that wavelength are the signature of the cold, dark hydrogen clouds found in our galaxy and beyond.

Because 21 cm radio waves have wavelengths about 400,000 times longer than the light we are seeing, to get the same ability to perceive detail as the human eye, our radio telescope would need a dish or lens around two kilometres in diameter.

The CHIME radio telescope at our observatory is about 100 metres square. The size is made possible by fixing the antenna to the ground, which limits how much sky it can see.

Fortunately there is another approach. Thanks to modern electronics and digital signal processing systems we can make a big antenna out of lots of smaller ones. The Very Large Array in New Mexico is an example, and the Atacama Large Millimetre Array (ALMA) in Chile is another.

“Millimetre” refers to the wavelength of operation, not the size of the antennas. The Canadian Hydrogen Observatory and Radio transient Detector (CHORD), under development at our observatory, will be another.

Making slick acronyms is an important part of modern science. CHORD will consist of 512 six-metre dishes, and will look rather like an insect’s compound eye. However, imaging distant galaxies and other cosmic radio sources needs a far greater power to resolve detail than our eyes. That means we need even bigger arrays of dishes.

That is why we are in the process of building what is likely to be the biggest radio telescope we can install on the surface of the Earth, the Square Kilometre Array (SKA). It will consist of thousands of small antennas, located mainly in South Africa and Western Australia. It is a massive international project, of which we are a part.

Pathfinder, or precursor, instruments have been built to develop and evaluate the required technology—one in South Africa called Meerkat, and the other in Australia, named, less poetically, ASKAP (the Australian Square Kilometre Array Pathfinder).

That image we saw at our recent meeting was obtained using the ASKAP radio telescope.

There is a reason we are investing in radio telescopes, such as ALMA and the SKA, located in the Southern Hemisphere. The centre of our galaxy is of major interest to astronomers. It passes overhead in the Southern Hemisphere. Here it just bobs above the southern horizon.

•••

• Jupiter lies high in the south-southeast after sunset and Saturn low in the south-southwest. • Venus rises shortly before dawn.

• The Moon will be full on the Dec. 26.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.

 

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The body of a Ugandan Olympic athlete who was set on fire by her partner is received by family

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NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.

Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.

She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.

Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.

“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.

It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.

Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.

Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.

Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.

“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.

He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.

Kenya’s high rates of violence against women have prompted marches by ordinary citizens in towns and cities this year.

Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.

The Canadian Press. All rights reserved.

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The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

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TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.

Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.

Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.

The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.

The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.

It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.

Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.

Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.

Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.

Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.

Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.

The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”

The Canadian Press. All rights reserved.

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B.C. sets up a panel on bear deaths, will review conservation officer training

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VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.

Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”

Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.

“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.

B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.

Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.

Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.

Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.

“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”

Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”

“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.

Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.

“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.

This report by The Canadian Press was first published Sept. 9, 2024.

The Canadian Press. All rights reserved.

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