Cotonou Stargazing & Astronomy Report

Key Sky Quality Metrics

SQM (mag/arcsec²)

19.00

Bortle class

Class 7 (Class 7)

Darkness Quotient

33%

Dataset

July 2026

Suburban/urban transition

Cotonou: The Practical Verdict

Cotonou, a major city in Benin, exhibits a high level of light pollution typical of dense urban environments. The night sky here falls under the categorisation of a poor urban/suburban sky, decisively limiting the visibility of celestial objects. The sheer intensity of the local light dome means that any detailed stargazing is heavily constrained.

From Cotonou, the Milky Way is completely obscured due to light pollution. Nonetheless, bright objects such as the Moon, planets, and bright double stars remain visible, making them the best targets for observers. Items requiring narrower bands, like some open clusters and emission nebulae under narrowband imaging, are possible but demand careful setup and processing. Deep-sky visuals and broad targets are generally discouraged.

For a marginal improvement in conditions, travelling about 22 km westward may offer some relief, reducing light pollution slightly and possibly revealing fainter stars. However, while improvements are present, they do not drastically alter the overall viewing experience.

At a Glance

Overall

Poor urban/suburban sky - This is a poor sky for astronomy. The Moon, planets, and a few bright objects remain viable, but deep-sky work is difficult.

Milky Way

Not visible - The Milky Way is not realistically visible from this level of light pollution.

Best targets from here

Moon, planets, bright double stars, bright open clusters, narrowband imaging with careful processing

Do not prioritise

visual deep-sky observing, broadband galaxies, reflection nebulae, Milky Way photography

Limited nearby upgrade

22 km W is the strongest nearby option but remains Bortle 5; the improvement is real but modest.

Good dark window

Cotonou retains astronomical darkness throughout the year, so seasonality is less extreme than at higher latitudes. The main limitation is light pollution, not the length of the dark window.

Frequently Asked Questions

Can you see the Milky Way from Cotonou?

No. Cotonou is a Bortle Class 7 sky with SQM 19.00, so the Milky Way is not visible from the city. For Milky Way photography, look for a Bortle 4 or darker site.

What Bortle class is Cotonou?

Cotonou is Bortle Class 7 (SQM 19.00), a poor urban/suburban sky for astronomy.

Is Cotonou good for stargazing?

Not for serious deep-sky observing. Cotonou is a poor urban/suburban sky where the Moon, planets, and a handful of bright targets are the realistic options from the city itself.

Is Cotonou good for astrophotography?

Broadband deep-sky imaging is heavily compromised from Cotonou and a Bortle 4 or darker site is strongly recommended. Narrowband imaging of bright emission nebulae remains viable from Cotonou with appropriate Ha or OIII filters.

What can you observe from Cotonou?

Primary targets from Cotonou include Moon, planets, bright double stars, bright open clusters, narrowband imaging with careful processing. Targets such as visual deep-sky observing, broadband galaxies, reflection nebulae are not realistic from this sky.

Where are darker skies near Cotonou?

The closest meaningfully darker mapped site is 22 km W, about 22 km west of Cotonou, reaching Bortle 5.

When is the sky darkest in Cotonou?

The sky over Cotonou is darkest around January, December.

Is light pollution in Cotonou getting better or worse?

The long-term trend for Cotonou is gradually worsening, with the sky brightening by about 0.04 SQM per year.

• 22 km W

  Direction

  W

  Distance (km)

  21.9

  SQM

  20.53

  Bortle

  5

• 6 km ESE

  Direction

  ESE

  Distance (km)

  5.8

  SQM

  19.67

  Bortle

  6

• 42 km E

  Direction

  E

  Distance (km)

  41.9

  SQM

  20.29

  Bortle

  6

• 77 km W

  Direction

  W

  Distance (km)

  76.6

  SQM

  20.63

  Bortle

  5