Open to everyone
Free public stargazing, workshops and a Youth Group. No prerequisites: just the urge to look up.
Castelldefels Astronomical Society · since 1987
The sky is not the limit: it is the beginning
We are the pioneering astronomical society of Baix Llobregat, with our own observatory and 39 years of uninterrupted activity. Public stargazing, astrophotography and real science, no clichés.
Orion A: star birth, phase by phaseJames Webb captures every phase of a star's birth at once in the Orion cloud: protostars, bipolar jets and glowing dust.James Webb · NASA, ESA, CSA, STScI · CC BY 4.0 · View the original ↗- years watching the sky, since 1987
- 39
- years watching the sky, since 1987
- active members
- 45
- active members
- observatory of our own, by Cal Ganxo
- 1
- observatory of our own, by Cal Ganxo
- sky reports this month
- 16
- sky reports this month
Who we are
An open association that turns curiosity into science
We are the pioneering society of Baix Llobregat. We popularise and research space science for everyone: from first-time telescope users to members contributing real data to world astronomy.
Rigour, never boring
Exact science told with beauty and narrative. History, mythology and breaking science, no clichés.
Neutral and local
Woven into Castelldefels life and global concerns; politically neutral and bias-free.
Our history
From a talk in 1987 to today
1987
The first nights
On 10 December the founding group held its first meetings and observations, after an astronomy course at the Casal de Cultura.
1988
Astrofels is born
In July the first astronomical society of Baix Llobregat was officially constituted.
·
The observatory
The Sergio López Borgoñoz observatory, behind the Cal Ganxo environmental centre, becomes our home.
Today
Citizen science
We track supernovae, novae and solar activity, and collaborate with UPC students. The dome stays open.
What we do · citizen science
We don't just watch the sky: we study it
Our members contribute real observations to world astronomy, from the Begues observatory and across the county.
Begues · Pepe Manteca
Hunting supernovae and novae
Tracking stellar explosions (SN 2026kid, SN 2026acd…) and the recurrent nova T CrB before its eruption.
Hα · white light
Solar monitoring
We document M-class flares and enormous prominences. The Sun, our closest star, every day.
Across the county
Deep-sky astrophotography
Galaxies, nebulae and planets captured by members from Sant Boi, Viladecans, Castelldefels or the Garraf.
With UPC
Education and outreach
Workshops, talks and collaboration with aerospace engineering students. Science, person to person.
Open sky
Public stargazing
Astronomical Fridays at Cal Ganxo: the Moon, the planets and the deep sky, free and for everyone.
12 Aug 2026
Eclipse special
We are getting the town ready for the total solar eclipse: how to watch it safely and understand what happens up there.
Latest blog post
What is happening this week under our sky
★ Latest · 7 June 20267 June 2026
Cena mágica y observación astronómica en Cal Ganxo 2026
Sábado 27 de junio, 20:30 h. Cena bajo el cielo del Garraf en la masía de Cal Ganxo, observación lunar con telescopio y la magia de Tony Montana.
Read on the blog
Sol4 June 2026
Gran erupción de clase M7 en el Sol
Erupción solar clase M7 en la región activa AR 4455, captada el 3 de junio por Pepe Manteca desde el Observatorio de Begues.
Photo: Pepe Manteca · Begues
Planetas31 May 2026
Imágenes de Júpiter, homenaje antes de dejarlo de ver
Júpiter con la Gran Mancha Roja claramente visible, por Joaquim Tarragó desde Sant Boi de Llobregat.
Photo: Joaquim Tarragó · Sant Boi
Estrellas31 May 2026
Nova recurrente T CrB, antes de la erupción
Seguimiento de la nova recurrente T Coronae Borealis desde Begues, a la espera de su erupción.
Photo: Pepe Manteca · Begues
Cielo profundo30 May 2026
Nueva vista espectacular de la nebulosa de Orión
Messier 42 en todo su esplendor, para recordarla hasta que vuelva al cielo de invierno.
Photo: José Gabriel Valero
Planetas30 May 2026
Venus brillante, sobre el Garraf
El lucero vespertino sobre el Garraf, desde los jardines del Castillo de Castelldefels.
Photo: Astrofels
Planetas29 May 2026
Un gran Júpiter, durante muchos meses
Júpiter, protagonista del cielo nocturno entre finales de 2025 y mediados de 2026, por varios autores de la agrupación.
Photo: Varios autores · Astrofels
Content and photographs: Astrofels blog, with full author credits
Members' astrophotography
Taken from here, with our own instruments
Agenda · open sky
Come look through the telescope
For now, the public agenda and sign-ups are managed on our blog and the Town Hall website:
27 Jun
Magic dinner and stargazing at Cal Ganxo
20:30 · Cal Ganxo farmhouse · dinner, the Moon through the telescope and magic
17 Jul
Workshop: solar filters to watch the eclipse safely
19:00 · Cal Ganxo · sign up at info@astrofels.org
31 Jul
Perseids night: meteor shower and deep sky
22:00 · observatory esplanade · free access
12 Aug
Total Solar Eclipse day
afternoon · safe observation with the society
🍺 Science & Beers
Astronomy face to face, beer in hand
Informal talks where breaking astrophysics is told without blackboard or tie. Bring your questions — and your thirst for cosmos.
The event of the century in Spain
Total solar eclipse · 12 August 2026
The first total eclipse visible from the Iberian Peninsula in over a century. We will get you ready to watch it safely — and to understand what happens up there.
— days · — h · — min
Join the eclipse dayBecome a member
Joining is easy — and it opens the dome
- Access to the Sergio López Borgoñoz observatory and its instruments
- Stargazing trips, courses and astrophotography training
- Real citizen-science projects: supernovae, the Sun, novae
- Astrofels Youth Group and activities for the whole family
- Newsletter with the agenda and breaking sky science
- 1
Write to us
An email to info@astrofels.org or the form. We will explain fees and activities, no strings attached.
- 2
Come stargazing
We invite you to an Astronomical Friday so you can meet us before deciding.
- 3
Join
Complete your membership with an affordable yearly fee. Welcome to the community.
Patronage · support us
The telescope stays open thanks to those who support it
Families, companies and institutions that believe in quality science outreach. Your contribution keeps the observatory, the free workshops and the Youth Group running.
Non-profit association · supported by
Networked with the cosmos
We don't watch alone: we are connected
We are part of a network of societies, observatories and dark-sky reserves — from Catalonia to the world.
Catalonia · neighbours
Dark sky · Starlight
The observatory
Sergio López Borgoñoz
Behind the Cal Ganxo environmental centre, in the heart of the Garraf. A dome, telescopes and a sky that still shows galaxies. 41.2787° N · 1.9759° E.
How to get thereObserving tonight?
Clear sky
Weather planning connected to our own station (WeatherCloud), coming here soon.
Contact
Write to us. We read you
Pick a topic and your message goes straight to the right mailbox — web, info or presidency — by secure email.
info@astrofels.org