Niko
@nikosarcevic.com
human person (she)
| cosmologist at Duke University
| member of @LSSTDESC @Roman
| did physics @XENONexperiment
| loves plots, coats, and The Wire
| opinions mine
| cosmologist at Duke University
| member of @LSSTDESC @Roman
| did physics @XENONexperiment
| loves plots, coats, and The Wire
| opinions mine
Reposted by Niko
Investigating the Dark Energy Constraint from Strongly Lensed AGN at LSST-Scale. Sydney Erickson et. al. https://arxiv.org/abs/2511.13669
November 25, 2025 at 11:16 AM
Investigating the Dark Energy Constraint from Strongly Lensed AGN at LSST-Scale. Sydney Erickson et. al. https://arxiv.org/abs/2511.13669
I can say with full confidence I’m the happiest person on this planet right now.
Seeing the Roman Space Telescope being assembled — and knowing it’ll be in orbit next year — just makes it unreal.
Seeing the Roman Space Telescope being assembled — and knowing it’ll be in orbit next year — just makes it unreal.
November 24, 2025 at 4:26 PM
I can say with full confidence I’m the happiest person on this planet right now.
Seeing the Roman Space Telescope being assembled — and knowing it’ll be in orbit next year — just makes it unreal.
Seeing the Roman Space Telescope being assembled — and knowing it’ll be in orbit next year — just makes it unreal.
It’s a wrap!
@nasaromantelescope.bsky.social NASA Roman HLIS Cosmology Project Infrastructure Team face to face meeting
Thank you to Bhuv, Mike and the rest of UPenn folk for hosting us 🙏
@nasaromantelescope.bsky.social NASA Roman HLIS Cosmology Project Infrastructure Team face to face meeting
Thank you to Bhuv, Mike and the rest of UPenn folk for hosting us 🙏
November 22, 2025 at 11:31 AM
It’s a wrap!
@nasaromantelescope.bsky.social NASA Roman HLIS Cosmology Project Infrastructure Team face to face meeting
Thank you to Bhuv, Mike and the rest of UPenn folk for hosting us 🙏
@nasaromantelescope.bsky.social NASA Roman HLIS Cosmology Project Infrastructure Team face to face meeting
Thank you to Bhuv, Mike and the rest of UPenn folk for hosting us 🙏
Hey all
I need help from my physics peeps (and beyond)
Do you (or if you are a PI: your students/postdocs) use numerical derivatives in your research?
Especially in inference (but also in general)
Apparently I can’t do a poll here so pls respond and share
I need help from my physics peeps (and beyond)
Do you (or if you are a PI: your students/postdocs) use numerical derivatives in your research?
Especially in inference (but also in general)
Apparently I can’t do a poll here so pls respond and share
November 17, 2025 at 12:24 PM
Hey all
I need help from my physics peeps (and beyond)
Do you (or if you are a PI: your students/postdocs) use numerical derivatives in your research?
Especially in inference (but also in general)
Apparently I can’t do a poll here so pls respond and share
I need help from my physics peeps (and beyond)
Do you (or if you are a PI: your students/postdocs) use numerical derivatives in your research?
Especially in inference (but also in general)
Apparently I can’t do a poll here so pls respond and share
The only acceptable way to start the Leiden research visit is to have coffee with Dr Evil Villain (in our secret Narnia caffe) @ivovanvulpen.bsky.social
(For those of you who don’t know, Ivo is responsible for the amazing wall formulas in Leiden; see photo 2 where Matthijs and I are kissing)
(For those of you who don’t know, Ivo is responsible for the amazing wall formulas in Leiden; see photo 2 where Matthijs and I are kissing)
November 10, 2025 at 10:51 AM
The only acceptable way to start the Leiden research visit is to have coffee with Dr Evil Villain (in our secret Narnia caffe) @ivovanvulpen.bsky.social
(For those of you who don’t know, Ivo is responsible for the amazing wall formulas in Leiden; see photo 2 where Matthijs and I are kissing)
(For those of you who don’t know, Ivo is responsible for the amazing wall formulas in Leiden; see photo 2 where Matthijs and I are kissing)
Happy to be back in one of the loveliest places on this planet
🇳🇱🚲🌷🧀🌊
🇳🇱🚲🌷🧀🌊
November 9, 2025 at 2:29 PM
Happy to be back in one of the loveliest places on this planet
🇳🇱🚲🌷🧀🌊
🇳🇱🚲🌷🧀🌊
Reposted by Niko
Interested in a fully funded PhD place in Experimental Particle Physics in Edinburgh?
We have fully funded studentships, including a specific scholarship for students from a Black heritage (including mixed Black background).
More info: inspirehep.net/jobs/3080808
We have fully funded studentships, including a specific scholarship for students from a Black heritage (including mixed Black background).
More info: inspirehep.net/jobs/3080808
INSPIRE
inspirehep.net
November 8, 2025 at 9:23 AM
Interested in a fully funded PhD place in Experimental Particle Physics in Edinburgh?
We have fully funded studentships, including a specific scholarship for students from a Black heritage (including mixed Black background).
More info: inspirehep.net/jobs/3080808
We have fully funded studentships, including a specific scholarship for students from a Black heritage (including mixed Black background).
More info: inspirehep.net/jobs/3080808
Reposted by Niko
Statistical properties of the gravitational force through ordering statistics. Constantin Payerne et. al. https://arxiv.org/abs/2201.08478
November 5, 2025 at 4:26 AM
Statistical properties of the gravitational force through ordering statistics. Constantin Payerne et. al. https://arxiv.org/abs/2201.08478
One of the perks of academia — you have awesome colleagues all over the world so dinners in great company are always guaranteed
November 4, 2025 at 10:06 PM
One of the perks of academia — you have awesome colleagues all over the world so dinners in great company are always guaranteed
Lovely day at the Paris observatory with old Twitter friends!
All Paris talks delivered!
All Paris talks delivered!
November 4, 2025 at 2:43 PM
Lovely day at the Paris observatory with old Twitter friends!
All Paris talks delivered!
All Paris talks delivered!
When two stats nerds from way back randomly find themselves in Paris at the same time — talk about serendipity!!!!
@knut.dundasmora.no 😍
It was beyond lovely to spend an afternoon in Paris with you
@knut.dundasmora.no 😍
It was beyond lovely to spend an afternoon in Paris with you
November 2, 2025 at 4:24 PM
When two stats nerds from way back randomly find themselves in Paris at the same time — talk about serendipity!!!!
@knut.dundasmora.no 😍
It was beyond lovely to spend an afternoon in Paris with you
@knut.dundasmora.no 😍
It was beyond lovely to spend an afternoon in Paris with you
Happy Halloween from me and my buggy code
October 31, 2025 at 7:49 PM
Happy Halloween from me and my buggy code
A little treat for myself: two adorable mini Kurt Geiger bags ✨
My first one was a Heathrow purchase two years ago — guess it was the start of a collection 👀
My first one was a Heathrow purchase two years ago — guess it was the start of a collection 👀
October 29, 2025 at 4:41 PM
A little treat for myself: two adorable mini Kurt Geiger bags ✨
My first one was a Heathrow purchase two years ago — guess it was the start of a collection 👀
My first one was a Heathrow purchase two years ago — guess it was the start of a collection 👀
Reposted by Niko
helloooooooooooooooooooo
wanna learn about telescopes and how to navigate the night sky? funny you mention that, because we're doing another starhopping and telescopes night with @spacecentreyvr.bsky.social on november 12!!
get your f r e e tickets here:
🔗 www.eventbrite.ca/e/rasc-vanco...
🔭🌌
wanna learn about telescopes and how to navigate the night sky? funny you mention that, because we're doing another starhopping and telescopes night with @spacecentreyvr.bsky.social on november 12!!
get your f r e e tickets here:
🔗 www.eventbrite.ca/e/rasc-vanco...
🔭🌌
RASC Vancouver Monthly Meeting - at H.R. MacMillan Space Centre
Join us for our RASC Vancouver Monthly Meeting at the H.R. MacMillan Space Centre for a talk about starhopping, and telescopes.
www.eventbrite.ca
October 23, 2025 at 12:05 AM
helloooooooooooooooooooo
wanna learn about telescopes and how to navigate the night sky? funny you mention that, because we're doing another starhopping and telescopes night with @spacecentreyvr.bsky.social on november 12!!
get your f r e e tickets here:
🔗 www.eventbrite.ca/e/rasc-vanco...
🔭🌌
wanna learn about telescopes and how to navigate the night sky? funny you mention that, because we're doing another starhopping and telescopes night with @spacecentreyvr.bsky.social on november 12!!
get your f r e e tickets here:
🔗 www.eventbrite.ca/e/rasc-vanco...
🔭🌌
clicked to generate a random xkcd and it could have not be more appropriate considering my current situation
xkcd.com/2797/
xkcd.com/2797/
Actual Progress
xkcd.com
October 22, 2025 at 5:09 PM
clicked to generate a random xkcd and it could have not be more appropriate considering my current situation
xkcd.com/2797/
xkcd.com/2797/
🤬 why does everything pass locally on macOS but CI (Linux) decides my cubic’s 3rd derivative is 24.0000001999 instead of 24?!
Apparently OpenBLAS and Apple’s Accelerate don’t round the same way 🤦♀️
IT IS UNIXXXXXXXX
Numerical analysis: 1, sanity: 0
(Managed to fix, still angry)
Apparently OpenBLAS and Apple’s Accelerate don’t round the same way 🤦♀️
IT IS UNIXXXXXXXX
Numerical analysis: 1, sanity: 0
(Managed to fix, still angry)
October 22, 2025 at 4:24 AM
🤬 why does everything pass locally on macOS but CI (Linux) decides my cubic’s 3rd derivative is 24.0000001999 instead of 24?!
Apparently OpenBLAS and Apple’s Accelerate don’t round the same way 🤦♀️
IT IS UNIXXXXXXXX
Numerical analysis: 1, sanity: 0
(Managed to fix, still angry)
Apparently OpenBLAS and Apple’s Accelerate don’t round the same way 🤦♀️
IT IS UNIXXXXXXXX
Numerical analysis: 1, sanity: 0
(Managed to fix, still angry)
6 °C in Durham this morning 🌿
Early woods + chilly air = time to grab a shovel! Cleared out a bunch of sweet gum trees — perfect, since we’re expanding the food gardens AND the lemurs get a feast 🍃
A wonderful morning at the Duke Lemur Center with my garden crew 🦋
Early woods + chilly air = time to grab a shovel! Cleared out a bunch of sweet gum trees — perfect, since we’re expanding the food gardens AND the lemurs get a feast 🍃
A wonderful morning at the Duke Lemur Center with my garden crew 🦋
October 21, 2025 at 2:47 PM
6 °C in Durham this morning 🌿
Early woods + chilly air = time to grab a shovel! Cleared out a bunch of sweet gum trees — perfect, since we’re expanding the food gardens AND the lemurs get a feast 🍃
A wonderful morning at the Duke Lemur Center with my garden crew 🦋
Early woods + chilly air = time to grab a shovel! Cleared out a bunch of sweet gum trees — perfect, since we’re expanding the food gardens AND the lemurs get a feast 🍃
A wonderful morning at the Duke Lemur Center with my garden crew 🦋
I also spent some hours this weekend giving my @github profile a glow-up — it’s orange 🟠 and has parrots 🦜
check it out: github.com/nikosarcevic
check it out: github.com/nikosarcevic
nikosarcevic - Overview
Cosmologist at Duke University. Member of LSST DESC and NASA Roman.
Combine all the probes! - nikosarcevic
github.com
October 13, 2025 at 1:26 PM
I also spent some hours this weekend giving my @github profile a glow-up — it’s orange 🟠 and has parrots 🦜
check it out: github.com/nikosarcevic
check it out: github.com/nikosarcevic
spent an embarrassingly long time making these plots (wanted to procrastinate) holy pagan gods, @matplotlib has been on fireeeee 🔥 the past few days
i think they’re correct … but for now i’m just gonna enjoy looking at them because they pretty 🤩
thanks to @matthijs.vanderwild.com for helping 😍
i think they’re correct … but for now i’m just gonna enjoy looking at them because they pretty 🤩
thanks to @matthijs.vanderwild.com for helping 😍
October 13, 2025 at 4:53 AM
spent an embarrassingly long time making these plots (wanted to procrastinate) holy pagan gods, @matplotlib has been on fireeeee 🔥 the past few days
i think they’re correct … but for now i’m just gonna enjoy looking at them because they pretty 🤩
thanks to @matthijs.vanderwild.com for helping 😍
i think they’re correct … but for now i’m just gonna enjoy looking at them because they pretty 🤩
thanks to @matthijs.vanderwild.com for helping 😍
The sky is particularly beautiful here in NC
So is the Moon 🌕🤩
So is the Moon 🌕🤩
October 5, 2025 at 11:05 PM
The sky is particularly beautiful here in NC
So is the Moon 🌕🤩
So is the Moon 🌕🤩
Reposted by Niko
In response to increasing activity, we wish to add more members to our Editorial Board. We're looking for expertise in any area of astrophysics, but people working in instrumentation or stellar astrophysics are particular welcome.
Please contact us here if you want to volunteer!
astro.theoj.org
Please contact us here if you want to volunteer!
astro.theoj.org
The Open Journal of Astrophysics
The Open Journal of Astrophysics is an arXiv overlay journal providing open access to peer-reviewed research in astrophysics and cosmology.
astro.theoj.org
October 4, 2025 at 1:28 PM
In response to increasing activity, we wish to add more members to our Editorial Board. We're looking for expertise in any area of astrophysics, but people working in instrumentation or stellar astrophysics are particular welcome.
Please contact us here if you want to volunteer!
astro.theoj.org
Please contact us here if you want to volunteer!
astro.theoj.org
New paper out, baby
We build & validate six intrinsic alignment models infused directly into weak lensing simulations, enabling robust inference beyond 2pt stats.
I led the full validation with MCMC chains—took years to get here! Excited this is FINALLY out 🎉
arxiv.org/abs/2509.25166
We build & validate six intrinsic alignment models infused directly into weak lensing simulations, enabling robust inference beyond 2pt stats.
I led the full validation with MCMC chains—took years to get here! Excited this is FINALLY out 🎉
arxiv.org/abs/2509.25166
September 30, 2025 at 5:45 AM
New paper out, baby
We build & validate six intrinsic alignment models infused directly into weak lensing simulations, enabling robust inference beyond 2pt stats.
I led the full validation with MCMC chains—took years to get here! Excited this is FINALLY out 🎉
arxiv.org/abs/2509.25166
We build & validate six intrinsic alignment models infused directly into weak lensing simulations, enabling robust inference beyond 2pt stats.
I led the full validation with MCMC chains—took years to get here! Excited this is FINALLY out 🎉
arxiv.org/abs/2509.25166
Yesterday I submitted 6 prs that were perfect not only to review but also to merge and rebase with no conflicts.
I was proud.
Today I do one pr on top of two PRs and suddenly there is a merge conflict cherry pick hell
I’m going to go listen to Maynard screams on YouTube
I was proud.
Today I do one pr on top of two PRs and suddenly there is a merge conflict cherry pick hell
I’m going to go listen to Maynard screams on YouTube
a man with a mohawk and a pink shirt is playing a saxophone .
ALT: a man with a mohawk and a pink shirt is playing a saxophone .
media.tenor.com
September 30, 2025 at 4:57 AM
Yesterday I submitted 6 prs that were perfect not only to review but also to merge and rebase with no conflicts.
I was proud.
Today I do one pr on top of two PRs and suddenly there is a merge conflict cherry pick hell
I’m going to go listen to Maynard screams on YouTube
I was proud.
Today I do one pr on top of two PRs and suddenly there is a merge conflict cherry pick hell
I’m going to go listen to Maynard screams on YouTube