# FLIP method raises JWST NIRCam coronagraph sensitivity 2–15 times; 51 Eridani b detected at 4.3 μm

- Published: 2026-11-05 04:06 UTC
- Section: Sky & Space › Astronomy
- Tags: FLIP algorithm, starlight subtraction, exoplanet direct imaging, JWST NIRCam coronagraph, 51 Eridani b, differentiable models, automatic differentiation, stellar PSF, Habitable Worlds Observatory
- URL: https://realtech.media/news/rt-e996e1ec0555f0aa616408b9_flip_method_raises/

**Authors report a physics-based starlight subtraction method tested on real JWST NIRCam data. It reduces dependence on the stability of reference images.**

![FLIP method raises JWST NIRCam coronagraph sensitivity 2–15 times; 51 Eridani b detected at 4.3 μm](https://sgzwpqqelzmajkcubgkl.supabase.co/storage/v1/object/public/rt-media/2026/11/b8959233e471842a.png)
*nature.com*

Astronomers led by researchers at Northwestern University have developed FLIP, a physics-based method of starlight subtraction for direct exoplanet imaging, according to a paper on nature.com [1]. The method was tested on observations from the NIRCam coronagraph of the James Webb Space Telescope (JWST). The authors report sensitivity 2–15 times higher than standard techniques, including the first detection of the planet 51 Eridani b at 4.3 μm [1]. To their knowledge, this is the first time such an approach has substantially improved sensitivity on real on-sky coronagraphic images [1].

## Why starlight subtraction is hard

Even the brightest young giant planets are about 10^5 times fainter than their host stars in the near-infrared [1]. A coronagraph blocks part of the starlight, but the stellar point spread function (PSF) still has to be modelled and removed from the image [1]. Standard algorithms build this model from a library of reference observations taken at other times or wavelengths, or of other stars [1].

Such empirical approaches are limited by instabilities. In space telescopes these are mostly pointing errors and thermal drifts, which make the reference PSF differ from the science PSF and reduce sensitivity [1]. Model-based PSF subtraction had been considered before, but the complexity of optical systems made accurate modelling difficult. With JWST NIRCam it had never given sensitivity better than standard techniques [1].

## How FLIP works

FLIP first calibrates a model of the instrument on reference images so that it reproduces the reference PSF. It then solves for small changes in the telescope aberrations that better explain the science image [1]. The method combines a multistep optimization with a flexible physical model [1]. Automatic differentiation is used to optimize millions of model parameters, and GPU-accelerated differentiable models make this computationally feasible [1].

The authors state that the framework can be extended to other ground-based and space-based observatories, including the Nancy Grace Roman Space Telescope and the Habitable Worlds Observatory (HWO) [1]. HWO aims to image Earth analogues around Sun-like stars, a brightness contrast of 10^10. This requires stability at the picometre level, 100 to 1,000 times better than JWST [1]. The authors note that the approach could potentially relax these stability requirements [1].

## Sources

1. [nature.com](https://www.nature.com/articles/s41586-026-11213-z)
2. [Наука.ua](https://nauka.ua/news/novij-algoritm-dopomig-teleskopu-dzhejms-vebb-pobachiti-prihovanu-za-svitlom-zori-ekzoplanetu)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-e996e1ec0555f0aa616408b9_flip_method_raises/