April is Global Astronomy Month and I would like to wrap up the occasion by highlighting the contributions of an amateur astronomer from Puerto Rico who is changing the world one astrophoto at a time. His name is Nelson Ortega Torres. By day, Nelson works as a fundraising coordinator for SER, the leading medical and rehabilitation center on the island for people with functional diversity. By night, Nelson points his telescope up to the sky from his hometown of Caguas, where he makes observations of the planets, Earth’s moon, and other celestial bodies in our Universe.

Credit: Nelson Ortega Torres
Nelson is a member of the NASA Solar System Ambassadors Program, a volunteer organization focused on public engagement and science communication. He is also the Vice President of Sociedad de Astronomía del Caribe (SAC), a non-profit organization that offers educational opportunities and star-gazing events for the general public.

Nelson Ortega during a public outreach event in Puerto Rico.
I recently interviewed Nelson during a Spanish Facebook Live event and asked him about his experiences with astrophotography. The following are excerpts from our conversation, condensed and edited for clarity:
Source of inspiration
Nelson got hooked on astronomy as an adult after observing the rings of Saturn through a telescope at an event organized by the SAC. Soon after that experience, he went ahead and purchased his first telescope and started volunteering at other events. Seeing people’s reactions when they first look through a telescope was very fulfilling for Nelson.
He shared the story of a dad who brought his child to one of the events at El Morro in Old San Juan. At first the dad hesitated to look through the telescope. Then after some encouragement he finally did. The dad was in awe and disbelief with what he was seeing and said:
Nelson quickly covered and uncovered the aperture of the telescope and asked "Can you see now the moons of Jupiter and the rings of Saturn?" After that night the dad reached out to Nelson asking for suggestions to buy a telescope for his son. “It is equally important to get adults excited about the Universe” Nelson highlighted.
Image processing
The composite image below of the Lagoon Nebula was selected by NASA as the Astronomy Picture of the Day in November 12, 2018. Nelson's astrophotos have also been featured by other organizations around the world. We asked Nelson to explain in ”arroz y habichuelas” (in simple terms) the process of taking such a gorgeous image.

The Lagoon Nebula. A nebula is a giant cloud of dust and gas in space. The Lagoon Nebula is 5,000 light years away from Earth. A light-year is the distance light travels in one year. Credit: Nelson Ortega
An image of this quality is made up of hundreds of photos taken over the course of weeks and even months! Nelson uses a monochrome camera and a combination of telescopes with different fields of view. A less powerful telescope takes pictures of the entire Nebula and a higher magnification telescope is used to resolve the details with high resolution. Each picture has an integration time of 5 minutes. Pictures are taken using separate RGB channels (for example, 50 pictures in red, 50 in green, and 50 in blue). Then a software like PixInsight is used to stitch the hundreds of photos to form a single composite image that is later processed by working out the color saturation.

Nelson's latest astrophotography of the Orion Nebula. Credit: Nelson Ortega
A piece of advice to aspiring astrophotographers
If you are planning to do astrophotography in Puerto Rico Nelson recommends the following locations: Pitahaya in Cabo Rojo and the islands of Vieques and Culebra.
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Cover Photo Credit: Nelson Ortega
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