A new 2025.2 release of GLASS, working towards Array API compatibility (incl. jax). This release moves the GLASS to the Cosmology API. That means you can easily run with a background cosmology provided by CAMB, Astropy, or your own classes through a common API standard. github.com/glass-dev/gl...

New Publication at the Open Journal of Astrophysics: "Shot noise in clustering power spectra" by Nicolas Tessore (University College London, UK) and Alex Hall (University of Edinburgh, UK) doi.org/10.33232/001...

This has been puzzling me. Given a set of redshift distributions nᵢ(z), i = 1, 2, ..., it's easy to work out the variance σᵢ² for each bin. How to fill in the rest of the "covariance matrix" so that it has intuitive properties? E.g. perfectly overlapping bins having σᵢⱼ = σᵢ² = σⱼ².

Shot noise in clustering power spectra. Nicolas Tessore et. al. https://arxiv.org/abs/2507.03749

Great results from DESI, but not nearly enough commentary about what phantom dark energy means in terms of GR

Fantastic little book for World Book Day from DK and Lego

First 2025 release of GLASS is out: github.com/glass-dev/gl... It comes with a big change that allows you to easily create FLASK-like simulations from a set of n(z) without simulating the entire lightcone. This isn’t usually the best way to go, but can sometimes be.

I feel like an idiot! Someone just showed there is a "web" tab for Google results that displays the plain old Google results from yesteryear!

BlueSky etc. are fine, but I wish we also had a dedicated space for professional discourse in Cosmology, Astrophysics, Astronomy, etc. Something like categorytheory.zulipchat.com, which seems phenomenally useful to me.

Is the Vatican City the country with the highest number of astronomy papers/capita?

Are there feeds with science content, instead of feeds with random content by scientists?

Hey @ojastro.bsky.social, do you accept "research notes" as understood by RNAAS? (short text, single figure or table, possibly no sections, etc.)

Sad to see the state of Bluesky after a long hiatus. Far too much galaxies, not nearly enough cosmology.

PSA: Numpy is currently deprecating and planning to remove the trapz() function in v2.0, due to appear in a month or so. This sounds like utter madness to me, since it's probably one of the most common operations I use.

As it turns out, this mysterious undocumented 𝑀-inversion parameter is really a 𝚖𝚒𝚗𝚟𝚎𝚛𝚜𝚒𝚘𝚗 parameter.

I find it very interesting that the publications describing the famous Hershey fonts are fairly easy to find, but the original data files seem lost to time. I bet that it will be the same 40 years hence, and papers about code survive much longer than the codes themselves.

I finally had enough trying to homogenise BibTeX files from multiple authors, and started on a no-dependencies, pure Python formatter for BibTeX: pip install tidybib # requires python>=3.10 tidybib main.bib # reformats main.bib Next step: detect duplicate entries with different keys.

I just set up an automated way to send out invite codes to astro folk who request them 😁 I think I can send out about 100/day. 🔭 Donate any codes you have here: forms.gle/R35p4MRSwpk2... & please share this code request form with other astro folks: forms.gle/GggKAPv8Vcrv...

Not many people seem to know about matplotlib's constrained layout mode. It makes life so much easier!

I have just now released version 2023.7 of our cosmological simulation code GLASS. A pretty cool addition are window functions which correspond to linear and cubic spline interpolation, respectively, giving much better approximations of radial functions. https://glass.readthedocs.io

For a simple lower bound on the accuracy of angular power spectrum codes (non-Limber etc.), you can compare the sum of all tomographic C_ells of your survey and the non-tomographic C_ell.