Cotonou Stargazing & Astronomy Report

Key Sky Quality Metrics

SQM (mag/arcsec²)

19.00

Bortle class

Class 7 (Class 7)

Darkness Quotient

33%

Dataset

May 2026

Suburban/urban transition

Cotonou: The Practical Verdict

Cotonou, a major city in the Littoral Department of Benin, experiences high levels of light pollution that severely impact stargazing. The overall quality of the night sky for astronomical observation is poor, with a Bortle rating of 7. This means that the Milky Way is not visible, and options for observing the cosmos are significantly restricted.

In Cotonou, the best stargazing targets are the Moon, planets, and bright double stars. These objects stand out against the light-polluted sky. Narrowband imaging of bright nebulae is possible but requires very careful processing. It is advisable to avoid visual deep-sky observing, broadband galaxies, and faint meteors, as these are mostly obscured by urban light.

There is a modest upgrade path. Allanwadan in the Atlantique Department, about 20 km to the west, offers slightly improved conditions with a Bortle rating of 5. While this does provide some enhancement, the gain is limited and local conditions will often be the prevailing factor.

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

Allanwadan, Atlantique Department 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 Allanwadan, Atlantique Department, about 22 km west of Cotonou, reaching Bortle 5.

When is the sky darkest in Cotonou?

The sky over Cotonou is darkest around January, November.

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.

• Allanwadan, Atlantique Department

  Direction

  W

  Distance (km)

  21.9

  SQM

  20.53

  Bortle

  5

• Finagnon, Littoral Department

  Direction

  ESE

  Distance (km)

  5.8

  SQM

  19.67

  Bortle

  6

• Appa, Lagos State

  Direction

  E

  Distance (km)

  41.9

  SQM

  20.29

  Bortle

  6

• Aklakou, Maritime Region

  Direction

  W

  Distance (km)

  76.6

  SQM

  20.63

  Bortle

  5