• 12th August 2024 - Friends Observing

    Perseid Meteor Shower - Observatory @10pm

    The Friends will gather at the Observatory from 10pm to monitor the peak of the annual Perseid meteor shower.
    This event is weather dependent and a final decision will be published on the day.


Marlborough College

Welcome to the Marlborough College Blackett Observatory, home to the largest refracting telescope in Wiltshire. The Observatory is a key facility for the study of Astronomy by pupils at Marlborough College, but is also open to the public through the Friends of the Marlborough Telescope membership scheme.

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What's Up!

Week of 17th January 2022

  • Astronomical twilight ends at 18:30 UT at the start of the week and at 18:39 UT by the end of the week
  • Try to spot Comet 19P/Borrelly in our southwestern evening sky. The comet is approaching perihelion on 1st February and lies just 1.2 AU away from Earth now. It is about magnitude +8, so binoculars or a telescope will be required. Look at an altitude of around 28° in Cetus, on the border with Pisces. A planetarium app will be useful to help locate the comet
  • The Moon is Full on Monday – the Wolf Moon
  • The Sun currently has eight active regions: AR 2924, 2925, 2926, 2927, 2929, 2930, 2931 & 2932. The sunspot number is 120
  • There are multiple evening ISS passes this week as follows:
    Tuesday: 18:50, S, max 14°
    Wednesday: 18:03, SSE to SE, max 13° and 19:38, SW, max 13°
    Thursday: 18:51, SW to S, max 32°
    Friday: 18:04, SSW to ESE, max 27° and 19:40, WSW, max 18°
    Saturday: 17:18, S to E, max 19° and 18:53, WSW to SSW, max 58°
    Sunday: 18:07, SW to E, max 50° and 19:43, W, max 19°


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All Sky Eye

The Latest View from the MCBO

The All Sky Camera operates from 30 minutes after sunset through the night until 30 minutes before sunrise. The latest image will be updated automatically every 5 minutes and the time lapse video is refreshed each morning at around sunrise. You can click the still image to open up a larger version, but please be aware that it will not automatically update until you return to this page – you can always manually refresh the page


Latest Still Image


Most recent time lapse video


18th January

Outreach visit: 14 Cubs and 3 Cub Leaders visited the Dome with GKWJ. It was cloudy
House visit: Due to multiple Covid absences the visit was run over Zoom with CEB cold at the Dome and all the C1 Shell pupils warm in their own rooms or at home. The evening was cloudy
Next House visit: Thursday 20th (NC)

17th January

Radcliffe Society: 16 members joined GKWJ, JAG & CEB at the Dome. A cold and clear evening allowed the meeting to take place at the Dome for the second month running. The full Wolf Moon drowned out all but the brightest targets. The Full Moon was observed through the 10-inch, including with the diagonal and eyepiece removed, allowing the Moon to be ‘held’ in the palm of the hand and its warmth felt. GKWJ set up the 8-inch outside to demonstrate how to capture stellar spectra; five bright stars (Capella, Menkalinan, Rigel, Alnitak and Betelguese) were targeted. The data were then processed on a laptop attached to a projector in the classroom, allowing members to follow along with the procedure. The spectra were calibrated and plotted together, allowing the differences between spectral classes to be clearly seen
Next meeting: 28th February

13th January

House visit: 13 Shell pupils from MO and a Tutor came up to join CEB at the Dome for the first clear Shell night in some time. The waxing Gibbous Moon made for a very light sky and prominent lunar shadows. Polaris and the Saucepan and Orion with Sirius and Betelgeuse were identified along with M32 Andromeda Galaxy just discernible with averted vision. The 10-inch tracked M42, the Orion Nebula where the Trapezium was clearly seen, though the nearby Moon made the nebulosity very faint
Next House visit: Tuesday 18th January (C1)

GCSE observing: All bar two Remove GCSE astronomers came up to the Dome to join CEB and GKWJ. Small instruments were used outside to do drawings of the 83% Moon and then high magnification (x235) drawings of the crater system Gassendi were done through the 10-inch

12th January

Outreach visit: 12 Scouts with 2 Scout Leaders and a Parent Helper visited the Dome with GKWJ. A clearing sky and cold conditions allowed the 77% Waxing Gibbous Moon to be viewed in the 10-inch. Outside, the group enjoyed a sky tour, identifying the Plough, Polaris, the W of Cassiopeia, Alcor and Mizar, Orion and the Orion Nebula (M42)

11th January

GCSE observing: All bar one of the Remove astronomy set came up to the Dome to join CEB and GKWJ. Sadly the sky clouded over and remained cloudy until they all left

6th January – 2022

House visit: The first Shell visit of the year took place as 13 pupils form MM joined CEB at the Dome. Small gaps in the clouds allowed brief viewing by eye of Betelgeuse and Orion, Castor and Pollux, the Pleiades, the Saucepan and Polaris.
Next House visit: 13th January (MO)

15th December

Outreach visit: 14 Scouts with 2 Scout Leaders visited the Dome with GKWJ. It was cloudy

11th December

Friends observing: Unfortunately, cloudy skies prevented the Friends from observing the Winter Wreath, but around 20 Friends joined CEB, GKWJ & JAG on Zoom to enjoy a presentation and Q&A session on the topic of ‘Comets’ instead


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