Plaskett fellow at the NRC Herzberg Astronomy and Astrophysics. Exoplanets, direct imaging instruments, and stats tools. #julialang enthusiast.

Joined January 2020
101 Photos and videos
Pinned Tweet
Announcing Octofitter (🐙), an ambitious tool for all kinds of exoplanet orbit modeling workflows: fit planet orbits to relative astrometry, proper motion anomaly, radial velocity, images, and more! [1/7] sefffal.github.io/Octofitter…
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The first astronaut in history to speak French while en route to the moon — Canada’s very own @astro_jeremy 🇨🇦
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This photo of Earth is EXTRA spectacular for a good reason... let me explain. Most images you see of Earth from space are the daylight side of the Earth, and it's obviously very bright (see my last image), this means stars are too dim to be seen with that bright exposure setting (low ISO, high shutter and / or stopped down aperture). BUT this image taken by the Orion crew looks so incredible because you can see the sun is BEHIND the earth, meaning it's night time on the side of the earth facing the crew in this image. So how do you expose a night time earth from space? Same way you do on Earth! A mixture of opening up the aperture (F4 in this case), cranking the ISO (51,200 here), and using a relatively long exposure (1/4 of a second). We can see the settings used by looking at the exif data from the camera. What this means is our camera is also sensitive enough to see stars in the background of Earth, leading to an extraordinary image!!! GREAT WORK!!! These are the kind of images I've been so excited to see!
Apr 3
Replying to @NASA
We see our home planet as a whole, lit up in spectacular blues and browns. A green aurora even lights up the atmosphere. That's us, together, watching as our astronauts make their journey to the Moon.
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fun fact: the human body contains 400 AU of DNA
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Great work by Sabina and co-authors! Plus lots of nice showcases of Octofitter and PairPlots :)
New paper! In work led by Sabina Sagynbayeva we quantify mission and ancillary data (RV, astrometry) requirements that enable "full system" (terrestrial AND giant planets) characterization with the Habitable Worlds Observatory. arxiv.org/abs/2507.21443
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New paper! In work led by Sabina Sagynbayeva we quantify mission and ancillary data (RV, astrometry) requirements that enable "full system" (terrestrial AND giant planets) characterization with the Habitable Worlds Observatory. arxiv.org/abs/2507.21443
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A surprising & little-known results in classical statistics: Mean (μ) and median (m) are within one std deviation: |μ−m| ≤ σ For unimodal densities, bound is even tighter |μ−m| ≤ 0.7746 σ This beautiful results first appeared in a 1932 paper by Hotelling & Solomons 1/3
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Our paper on a differentiable spectral model, ExoJAX2, has been accepted by ApJ. In this paper, we use HMC-NUTS to analyze JWST’s native-resolution transmission, high-dispersion spectra of a brown dwarf from Subaru, and Jupiter’s reflected light. arxiv.org/abs/2410.06900 1/N
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Just learned that am being awarded the J. S. Plaskett medal for most outstanding doctoral thesis in astronomy in Canada. Thank you @AstroCanada, and my committee & @PHASTatUVIC for the nomination!
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Taking my glasses off when I get home after a long day because I’ve seen enough
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The Flag That Unites Us. Happy #FlagDay! 🇨🇦
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12 Feb 2025
Researchers from UVic’s Astronomy Research Centre used the James Webb Space Telescope to captured a rare glimpse of how young planets are forming. This groundbreaking discovery reveals how planets compete with their host star for material shorturl.at/Ei7Fh @ArcUvic #JWST
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William Thompson retweeted
Just saw someone saying using the em-dash is a sign of something being written by AI, because real people rarely use it. This is terrible news for everyone like me who has an unhealthy emotional attachment to the em-dash.
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Load in 4k to spot the ISS
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Law of controls: write C code for real-time embedded hardware. You can't use #python or #rstats etc. for that, right? With #julialang v1.12, we demonstrate it's possible to ahead of time compile to small binaries for use in controls applications. #sciml arxiv.org/abs/2502.01128
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The heretical thought occurs to me as I dig into “The Stars, Like Dust” that I do not in fact enjoy Isaac Asimov’s long form writing.
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Though many events in space take place over vast timescales, these rings (Webb spotted 17 of them) are moving outward from their stars at more than 1600 miles/s, making them noticeably different from one year to the next. This animation shows changes in WR140 between 2022-2023.

ALT The animation alternates between two James Webb Space Telescope images of the two-star system Wolf-Rayet 140, the first taken in 2022 and the second in 2023. Both show a bright white point of light surrounded by 17 regularly spaced, hazy dust shells at the bottom, right, and upper right. There is noticeably less color in the upper left. The central point, where the two stars are located, has a rough hexagon shape. By alternating between them, it’s clear that the dust shells are moving outward, becoming wider.

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One photo with: Milkyway, Zodical light, @Starlink satellites as streaks, stars as pin points, atmosphere on edge showing OH emission as burned umber (my favorite Crayon color), soon to rise sun, and cities at night as streaks. Taken two days ago from Dragon Crew 9 vehicle port window.
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Silver lining of being in unexpectedly Ottawa this week instead of at #AAS245 is the shawarma
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