> For the complete documentation index, see [llms.txt](https://satdocs.hydrosat.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://satdocs.hydrosat.com/product-details/changelog.md).

# Changelog

<details>

<summary><strong>May 21, 2026: Footprint Geometry Correction</strong></summary>

We've deployed a minor fix to ensure representativeness of STAC item footprint geometries with actual imaged area.

</details>

<details>

<summary><strong>March 31, 2026: Coregistration Improvements</strong></summary>

We've refined our mutual information-based coregistration workflow for improved feature matching between the LWIR and VNIR data.

</details>

<details>

<summary><strong>February 24, 2026: Geometric Processing Improvements</strong></summary>

We've updated our georeferencing and VNIR band alignment workflows to improve geolocation accuracy and band-to-band registration. This release includes:

1. An enhanced optical distortion correction to reduce residual along-track offsets
2. Use of a digital elevation model (DEM) to improve band-to-band registration over complex terrain

</details>

<details>

<summary><strong>February 5, 2026: Level-1 Unit Changes</strong></summary>

We've modified the units for our Level-1A and Level-1B data products.&#x20;

#### Before The Change

Previously, L1A and L1B imagery assets contained per-band digital number data. To arrive at radiance, the user needed to apply gain and offset coefficients provided in product metadata.

#### After The Change

**Level-1A Products**

* L1A imagery assets now natively contain per-band top-of-atmosphere (TOA) radiance values. Gain and offset coefficients are applied as part of Hydrosat's data processing.
  * Units: W/m<sup>2</sup>/sr/μm
  * Scaling factor: 0.01 (VNIR), 0.0001 (LWIR)

**Level-1B Products**

* L1B imagery assets contain per-band TOA reflectance data (for VNIR bands) and brightness temperature data (for LWIR bands).
  * Units: Unitless (VNIR); Kelvin (LWIR)
  * Scaling factor: 0.0001 (VNIR); 0.01 (LWIR)

**Conversions**

* Hydrosat provides a full suite of coefficients in product metadata for conversion between TOA radiance and reflectance (or brightness temperature). For more information on usage, see [this page](https://satdocs.hydrosat.com/product-details#conversions) or our product guide.

</details>

<details>

<summary><strong>January 27, 2026: Thumbnail Colorization Improvements (LWIR)</strong></summary>

We've improved the contrast and visual consistency in our L1B and L2 thermal thumbnails and previews. This includes:

* Consistent scaling across the full imaging strip rather than within individual scenes.
* A switch from the `inferno` color ramp to a modified `RdYlBu_r` color ramp, where cooler pixels are shown in blue and warmer ones in red. These colors map to predictable temperatures; the breakpoint from blue to yellow occurs at approximately 0 degrees Celsius.&#x20;

This change has no impacts on the underlying data.

</details>

<details>

<summary><strong>January 20, 2026: Noise Mitigation</strong></summary>

We've implemented a minor correction for noise in the thermal products.

</details>

<details>

<summary><strong>January 14, 2026: Thumbnail Colorization Improvements (RGB)</strong></summary>

We've released a color curve approach that improves the visual contrast in our true color thumbnails. This change has no impacts on the underlying data.

</details>

<details>

<summary><strong>December 17, 2025: Updated Cloud Mask</strong></summary>

We've released an improved cloud mask, which uses a U-Net convolutional neural network architecture. The new model outperforms our baseline Fmask approach across several key metrics.

</details>