Blackett Observatory Dome
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Marlborough College
Oxford Astrophysics
Green Templeton College

Naked-eye Comet NEOWISE is now visible in the Northern night sky
Best in binoculars, but you need a good horizon as it is low


Unfortunately the Observatory will remain closed to visitors
until all social distancing measures are finally eased

NASA Astronomy Picture of the Day

What's Up!

Week of 13th July

  • Astronomical twilight does not end until 21st July

  • Comet NEOWISE (C/2020 F3) is the finest comet to appear in our skies for many years. It is now circumpolar and is visible from sunset to sunrise. However, it is very low to the northern horizon, so you need to choose your observing location accordingly. Through the week it increasingly becomes an evening object. It is at 10° altitude and 338° azimuth at 23:00 BST on Monday evening, moving to 8° alt, 10° az by 02:00 BST that night. By Friday, it is at 16° alt, 330° az, at 23:00 BST and 9° alt, 359° az, at 02:00 BST on Saturday morning. This is a must see object, let's hope for clear skies!

  • The planets make an impressive line up across the southern sky this week. Jupiter (mag -2.8) reaches opposition on Tuesday, it is also at perigee, making this the best time to observe Jupiter at its largest and brightest in our sky. It is visible along with Saturn (mag 0.1) at an altitude of around 14° above the southeastern horizon throughout the evening. For the night owls and early risers, Mars appears above the eastern horizon after midnight, followed by Venus, which rises in the northeast at about 02:45 BST. The waning crescent Moon rises within 3° of Venus on Friday morning and will make an impressive sight

  • The Moon is waning and starts the week at Last Quarter on Monday

  • The Sun currently has no active regions

  • The ISS is visible in our skies again with evening passes as follows:
    Monday - 23:13, SSW to E, max 25°
    Tuesday - 22:26, S to E, max 18°
    Wednesday - 23:13, 23:13, SW to E, max 47°
    Thursday - 22:26, SW to E, max 34°
    Friday - 23:14, WSW to E, max 76°
    Saturday - 22:26, WSW to E, max 61°
    Sunday - 23:15, W to E, max 86°


Random Blackett Image
Past Events - Ogbourne St. Andrew and St. George CE School Visit


22nd June

Radcliffe Society: Nine members of the society met online for the final meeting of the academic year. What's Up for the summer was presented by GKWJ, followed by three excellent pupil presentations entitled, 'Fractals and Chaos', 'Relatively Good Evidence' and 'SpaceX to Solar Supermarkets'. Next meeting: 21st September

21st June

Solstice observing: Stargazing live at MCBO! Thanks to Gavin and some excellent new camera technology, CEB and GKWJ were able to hold a live streamed (via Zoom) stargazing session. Starting in Civil Twilight just after the Sun set, we identified the northern Solsticial setting point. Stars were then observed as they came out in order of magnitude, once Nautical Twilight started. By luck we were then treated to the best Noctilucent Cloud display so far this season (always best near the Solstice) and were able to watch as the luminous, bluey and greeny wisps changed formation. Typically looking like ripples on the shore or sand wind-blown into peaks and troughs, the clouds are not part of the weather system and are much higher at 80km or so. They are now thought to be ice crystals seeded by meteor impact trails. The group of Friends disbanded around midnight, after we had toured some prominent Summer asterisms and finished with Jupiter in the South East

21st May

Solar open day: The annual solar observing session could not take place at the Dome this year due to the social distancing measures in place. Not wanting to be thwarted by this, CEB and GKWJ attempted the first ever live streaming astronomy event for Friends and College staff. High hazy cloud rendered the 10inch ineffective, so live views from the River Park Observatory through a Lunt 2inch H alpha solar telescope were streamed via Zoom. Around 40 visitors dropped in to the event over the course of the afternoon. The seeing was poor at best. Two plage areas were observed on the surface, but otherwise it was featureless, to be expected given that we are still in the solar minimum. The main attraction was a large prominence on the northeast, oncoming limb. It extended to about four Earth diameters above the solar surface, with two loops extending out in opposite directions from the main area. This prominence complex was clearly seen to develop and change over the two and a half hour session. Numerous small explosions of plasma were seen to bubble up and collapse nearby on the limb. Unfortunately, gathering cloud spoiled the view towards the end of the session, but it was a great success and opened the way for new methods of astronomical observing at Marlborough College.

4th May

Radcliffe Society: The society met online via Zoom for the first time. GKWJ gave the monthly What's Up, JAG presented on Current Comets and two pupils gave presentations on 'The Baryon Asymmetry Problem' and 'Physics in Cinema'. Next meeting: 22nd June

22nd March

Messier Marathon: it was a great shame that the College Messier Marathon attempt had to be cancelled this year due to the Coronavirus outbreak. Typically, conditions could not have been more perfect: New Moon and clear skies. GKWJ and JAG could not let the opportunity pass by, so decided to make the Messier Marathon 2020 attempt 'behind closed doors' on Sunday night. The session started at 19:20 with a stunning view through the 10inch of Venus in its dichotomy phase. The hunt for as many of the 110 Messier objects with the 10inch then started in earnest. Two online Zoom sessions were held during the evening, allowing a number of the GCSE pupils and DGR to join the hunt from home. As we were working in very dark conditions this was more of a radio link than video! Highlight objects through the night included: open clusters M34, M35, M38, M52 and M67, galaxies M51, M81 and M82, planetary nebulae M27 and M57, nebulae M17 and M42 and globular clusters M3, M13, M14 and M92. During the night, Comet ATLAS was viewed twice and its significant movement was noticed. Great empathy was felt with Messier, who was of course trying to find new comets, compiling his catalogue of objects that were not comets and to be avoided on future nights. It is amazing how much a globular cluster looks like a comet! Several breaks were taken and the night sky outside was admired; Betelgeuse was noted to be markedly brighter at around mag +1. Saturn and Jupiter, with all four Galilean moons visible, were viewed through the 10inch in the morning twilight. The Marathon finished with M2 being the final observation at 04:53. In total, 96 out of 110 Messier objects were seen. The fourteen missed were due either to the bright evening and morning twilight sky or because they were below the horizon for the 10inch. It was a very successful night, but hopefully the 2021 attempt will be enjoyed by a full team of pupils too.

11th March

Radcliffe Society: 10 pupils from Sixth Form, Hundred and Remove attended the March meeting of the Radcliffe Society with GKWJ and JAG. GKWJ gave the monthly What's Up guide, a video interview with Subir Sarkar (University of Oxford) discussing 'The Evidence for Dark Energy' was watched and then two Upper Sixth pupils gave presentations on 'The Standard Model and Neutrinos' and 'Entropy'. Next meeting: 4th May

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