Milky Way and meteor above the dark skies at Leonard’s Lookout in rural Granada

The evidence behind our dark sky description

Dark-Sky Quality at Leonard’s Lookout

Independent research, regional sky-brightness modelling and the reason we describe the property conservatively as Bortle 3.

See the evidence

Fuente Nueva · Granada Geopark

Exceptionally low artificial sky brightness

Leonard’s Lookout is located in Fuente Nueva, within the municipality of Orce and the Granada Geopark.

Official research by the Instituto de Astrofísica de Andalucía, IAA-CSIC, indicates exceptionally low levels of artificial sky brightness across this part of the Geopark. When our location is plotted against the study’s published maps, it falls within an estimated zenith sky-brightness band of approximately 21.7–21.8 mag/arcsec².

The available evidence is broadly consistent with Bortle 2–3 conditions. To avoid overstating what a regional model can prove at one individual property, we describe the skies at Leonard’s Lookout conservatively as Bortle 3.

Estimated zenith sky brightness21.7–21.8mag/arcsec²

Technical interpretationBortle 2–3depending on conditions

Public descriptionBortle 3conservative site description

Research basisIAA-CSICGranada Geopark study

Where the figure comes from

Measured across the Geopark, modelled across the landscape

The Granada Geopark night-sky study was produced by the Office for Sky Quality at the Instituto de Astrofísica de Andalucía, IAA-CSIC, for the Diputación de Granada.

The research covered 4,722 km² across 47 municipalities. During 2021 and 2022, the team collected 107,861 ground-based sky-brightness records using mobile Sky Quality Meters, including instruments fitted with photometric filters to record colour information.

These measurements were combined with satellite observations and spatial modelling to create continuous maps of zenith sky brightness across the Geopark.

Plotting the Fuente Nueva area against the published V-band map places Leonard’s Lookout within the study’s darkest modelled category, at approximately 21.7–21.8 mag/arcsec². The highest calculated value reported across the entire study area was 21.77 mag/arcsec².

This is a modelled estimate for the area, supported by regional ground measurements. It is not a permanent meter reading taken at the property.

View the official IAA-CSIC study

Interpreting the number

What the evidence means in practice

What does 21.7–21.8 mag/arcsec² mean?

Sky brightness is commonly expressed in magnitudes per square arcsecond. Unlike many measurement scales, a higher figure represents a darker sky.

A value around 21.7 mag/arcsec² indicates a very dark zenith with relatively little contribution from artificial light. For astrophotographers, darker sky backgrounds can improve contrast and make it easier to record faint structures in nebulae, galaxies, star fields and the Milky Way.

The figure describes background sky brightness. It does not, by itself, guarantee good seeing, transparency or weather on any particular night.

Why we describe the property as Bortle 3

The Bortle scale is an observational classification rather than a direct conversion from a sky-brightness measurement.

An observer assigns a Bortle class by considering several visible characteristics, including the structure of the Milky Way, zodiacal light, airglow, limiting magnitude and the presence of artificial light domes around the horizon.

Sky-brightness values around those modelled for Fuente Nueva can be associated with Bortle 2 conditions. However, the practical experience on any particular night can be affected by atmospheric transparency, humidity, dust, natural airglow, moonlight and light visible towards individual horizons.

For that reason, the evidence supports a realistic Bortle 2–3 interpretation, while Bortle 3 is the more conservative and defensible description for general use across the Leonard’s Lookout website. On suitably clear, transparent and moonless nights, conditions may be closer to the darker end of that range.

Evidence, not overclaiming

What the research does — and does not — prove

The study provides strong independent evidence that Leonard’s Lookout lies within an exceptionally dark part of the Granada Geopark.

It does not provide an official Bortle number assigned to the property.

It does not provide a permanent year-round reading from Leonard’s Lookout.

It does not guarantee identical conditions every night.

It does not measure cloud cover, seeing or transparency for future dates.

Moon phase, weather, atmospheric conditions and occasional local or distant lighting can all affect the sky visible on an individual night.

Guests planning an imaging stay should therefore consider the Moon, target position, astronomical darkness and seasonal weather alongside the underlying darkness of the location.

Granada Geopark

Within a Starlight-certified destination

Leonard’s Lookout lies within the Granada Geopark, which received international certification as a Starlight Tourist Destination in 2025.

The certification recognises the wider Geopark’s night-sky quality, efforts to limit light pollution and suitability for sustainable astrotourism. The IAA-CSIC sky-quality study formed part of the technical evidence supporting that process.

Important distinction: this is regional certification covering the Granada Geopark. Leonard’s Lookout has not been individually certified by the Fundación Starlight, and the certification does not assign the property a Bortle class.

Read about the Starlight certification

Sources and further reading

The source material behind the claim

IAA-CSIC: The night-sky quality of the Granada GeoparkThe official explanation of the research, measurement programme and methodology.

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Full scientific-technical report: Granada Geopark night-sky studyThe published report and mapped evidence.

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Fundación Starlight: Granada Geopark certificationConfirmation of the Geopark’s status as a Starlight Tourist Destination.

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Astrophotography telescope setup at Leonard’s Lookout in rural Granada

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Return to the main Astrophotography page for details of the outdoor setup areas, power, connectivity, accommodation and the types of imaging supported at Leonard’s Lookout.

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