kottke.org posts about Andrew McCarthy

The Sun, In All Its Glory

posted by Jason Kottke   Mar 23, 2023

astounding image of the Sun

detail of an astounding image of the Sun

Good morning, sunshines! Well, amateur astrophotographer Andrew McCarthy has done it again. Collaborating with Jason Guenzel, he has produced this absolutely gobsmacking image of the Sun.

The aptly named “Fusion of Helios” is a fusion from the minds of two astrophotographers, Andrew McCarthy and Jason Guenzel. Using a custom-modified hydrogen alpha solar telescope, the combined data from over 90,000 individual images was jointly processed to reveal the layers of intricate details within the solar chromosphere. A geometrically altered image of the 2017 eclipse as an artistic element in this composition to display an otherwise invisible structure. Great care was taken to align the two atmospheric layers in a scientifically plausible way using NASA’s SOHO data as a reference.

I’ve included the full image and my favorite crop (the solar tornado the height of 14 Earths was a close second) above, but do yourself a big favor and check out the largest image available (which is still way smaller than the 140 megapixel final image they produced). If you’re curious about the process, here’s how McCarthy gets his Sun photos:

So how do I resolve atmospheric details, like spicules, prominences, and filaments? The trick is tuning the telescope to an emission line where these objects aren’t drown out by the bright photosphere. Specifically, I’m shooting in the Hydrogen-alpha band of the visible spectrum (656.28nm). Hydrogen Alpha (HA) filters are common in astrophotography, but just adding one to your already filtered telescope will just reduce the sun’s light to a dim pink disk, and using it without the aperture filter we use to observe the details on the photosphere will blind you by not filtering enough light. If you just stack filters, you still can’t see details. So what’s the solution?

A series of precisely-manufactured filters that can be tuned to the appropriate emission line, built right into the telescope’s image train does the trick! While scopes built for this purpose do exist (look up “coronado solarmax” or “lunt solar telescope” I employ a heat-tuned hydrogen alpha filter (daystar quark) with an energy rejection filter (ERF) on a simple 5” doublet refractor. That gives me a details up close look at our sun’s atmosphere SAFELY. I’ve made a few custom modifications that have helped me produce a more seamless final image, but am not *quite* yet ready to share them, but just the ERF+Quark on a refractor will get you great views.

Photography has always been a combination of technology, artistry, and wrangling whatever light you can get to best express the feeling that you’re going for — astrophotography certainly dials that wrangling up to 11.

Prints of this image (and some digital downloads) are available in various sizes from McCarthy and Guenzel.

A Close-Up Photo of Comet Leonard by an Amateur Astronomer

posted by Jason Kottke   Jan 03, 2022

Comet Leonard

Using a composite of 25 different shots done over a period of 12 minutes in his backyard, amateur astrophotographer Andrew McCarthy created this stunning image of Comet Leonard. From PetaPixel:

Processing comet images is a challenge because even in the span of 12 minutes, the comet drifts across the frame relative to the background stars,” McCarthy tells PetaPixel. “Due to the comet’s motion, it has to be stacked differently. I tell the software to stack the images based on the comet position and star positions separately, which is then combined together to produce an image with the comet and stars both sharp.

See also this image of Leonard and McCarthy’s colorful photo of a full moon.

Full Moon

posted by Jason Kottke   Sep 21, 2021

a full moon with a very colorful surface

The full moon was wonderful last night and Andrew McCarthy captured this colorful image of our nearest celestial companion. McCarthy explained where all those colors come from:

Back to this image, this was captured through a telescope and involved capturing thousands of frames to reveal the details. But what about the colors? The moon is gray, of course, but not *perfectly* gray. Some areas have a subtle blue tint, and others have a more orange tint. By teasing out those subtle colors, I can reveal the mineral composition of the moon! Blues denote titanium presence, while orange shows iron and feldspar present in the regolith. You can also see how impacts paint the surface with fresh color in the ejecta as they churn up material.

A print is available, but only for a very limited time (~6 more hours as of pub time).

Let’s Bask in This Photo of the Sun

posted by Jason Kottke   Apr 27, 2021

The Sun

Astrophotography enthusiast Andrew McCarthy took a 140-megapixel photo of the Sun yesterday and, gosh, the Sun is just so cool to look at. I don’t know if you can see it above, but there’s a little something hidden in the photo, a transiting ISS:

The ISS transiting the Sun

The full-size image is available to McCarthy’s supporters on Patreon.

This Striking Image of the Moon Is a Combination of 100,000 Photos

posted by Jason Kottke   Jan 15, 2020

Backyard astronomer Andrew McCarthy has created some arresting images of various objects in the sky, including galaxies, planets, the Sun, and nebulas. Perhaps his favorite subject is the Moon and for one of his first images of 2020, he combined 100,000 photos to make this image of the first quarter Moon.

Andrew McCarthy Moon

Some detail:

Andrew McCarthy Moon

*low whistle* McCarthy uses some digital darkroom techniques to bump up the dynamic range, which he explained in the comments of a similar image.

The natural colors of the moon were brought out here with minor saturation adjustments, but those colors are completely real and what you could see if your eyes were more sensitive. I find the color really helps tell the story of how some of these features formed billions of years ago.

In one of his Instagram Stories, he shows how he photographs the Moon, including dealing with temperature changes over the course of the session — “when it’s cold, the telescope shrinks, and the focus changes”.

McCarthy sells digital copies of his images (as wallpaper or to print out) as well as prints. (via moss & fog)