Sky Notes for September 2013 with James Abbott #stargazing

On August 14th, a Japanese astronomer discovered a Nova in the constellation of Delphinus which brightened to become just visible with the unaided eye from dark sites. The star system that is the source of the Nova reached some 25,000 times brighter than be-fore the outburst which at our distance from it equated to about mag 4.5. Although now slowly fading, it is still a bright binocular object.

Image: Dennis di Cicco/S&T

The spectral signature is that of a classical Nova. In a binary star system, gas is being drawn from a cool giant star into an accretion disk around a dense white dwarf. When enough gas has built up on the smaller star, a nuclear fusion reaction is triggered with the ac-companying massive increase in brightness. Such events can recur in the same system – such as RS Ophiuchi.

Saturn and Venus will be close together in the evening twilight around mid-month but are both very low in the West as it gets dark. The young Moon will be near the planets on the evenings of the 8th and 9th.


For those up before dawn, Jupiter will be dominating the early morning skies in the East, located in Gemini.

Full Moon this month is on September 19th and will be 37 degrees in altitude when due South, much higher than the low summer Moons of late. The September Moon is a classic Harvest Moon, the time of rising on successive evenings only advancing slowly so that even on the 23rd, 4 days after Full, the Moon is still up before 9pm BST.


By the last week of the month the Moon finally leaves the late evening sky. The constellations are now turning to-wards Autumn with Taurus rising in the East by 11pm BST. The Autumnal Equinox arrives on the 22nd September at just before 10pm BST.

It is expected that this month will see the start of part-night street lighting in the council areas of Chelmsford City and Braintree District. Most of the lights will go off between midnight and 5am, though town centres and industrial estates, areas around railway stations, etc will stay on all night. Maps are available showing all of the villages and towns affected with individual streetlights detailed.


Essex County Council do include reducing light pollution as one of their reasons for the programme:
“To save money and reduce our carbon emissions and light pollution, we will be turning off some of our street lights at night – this is called part night street lighting.”

After many years with this programme being under discussion it will be intriguing to see what the effect is on our night skies. There will be a reduction in the light pollution domes over the towns but it is unlikely to be “Dark Sky Park” quality skies for Essex!

James Abbott is an astronomer, NEAS member and CfDS Regional Information Officer.

You can download a free map of the evening sky here:


Posted on 6 September, 2013, in Astronomy News, Observing News, Popular Science, Stargazing and tagged , , , , , , , , . Bookmark the permalink. Comments Off on Sky Notes for September 2013 with James Abbott #stargazing.

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