Add "Signal, Noise and Histograms"

README.md

@@ -38,6 +38,7 @@ Contributions are welcome. Please read the [contributing guideline](CONTRIBUTING
 - [Mastering Flat Frames: Gain matching](https://www.astroworldcreations.com/blog/understanding-flats-part-1-gain-matching) - This blog series by Willem Jan Drijfhout will take you on a deep dive into the topic of flat frames ([Part 2: Flat Panels compared](https://www.astroworldcreations.com/blog/understanding-flats-part-2-flat-panels-compared), and [Part 3: Bias, Flat-Darks and Conclusions](https://www.astroworldcreations.com/blog/understanding-flats-part3-conclusions)).
 - [Optical Glass Types](https://www.stellarvue.com/optical-glass-types/) - What makes a top-tier telescope? This article will clear up some common misconceptions.
 - [Selecting a Guide Scope and Autoguiding Camera for Astrophotography](https://agenaastro.com/articles/guides/selecting-a-guide-scope-and-autoguiding-camera-for-astrophotography.html) - Choosing the right autoguiding equipment can be challenging. This guide will help with making the right decision.
+- [Signal, Noise and Histograms](https://jonrista.com/the-astrophotographers-guide/astrophotography-basics/signal-noise-and-histograms/) - Part of Jon Rista's Astrophotography Basics series, this article provides a great bit of theory around signals, noise and histograms.
 - [Sky-Watcher AZ-GTI: The Perfect Mount for Mobile Astrophotography](https://milkywayphotographers.com/article/2021/03/11/sky-watcher-az-gti-the-perfect-mount-for-mobile-astrophotography/) - The Sky-Watcher AZ-GTI mount was never meant for astrophotography. Oh, the irony!
 - [The Differences between CCD and CMOS Sensors](https://www.atik-cameras.com/news/difference-between-ccd-cmos-sensors/) - One of the best explanations to CCD vs. CMOS camera sensors.
 - [The best solution of 55mm back focal length](https://astronomy-imaging-camera.com/tutorials/best-back-focus-length-solutions-55mm/) - Guidance on how to reach the 55mm back focal length with ASI cameras.