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Mon, 28 Aug 2017 - Eclipsing Binary Predictions : 2017 September-October

Here are predictions for eclipses that are reasonably favourable from the UK during September and October:

Times are in UT (same as GMT, 1 hour behind BST - so, for example, 22.7h UT is 23.7h BST)

RZ Cassiopeiae

Eclipses last 4.8h, with most of the brightness changes taking place during the middle 3 hours. The times shown below are for the mid-point of the primary eclipses. Eclipses are not quite total, so there is no spell of constant brightness at mid eclipse.

Date Mid-Eclipse (UT)
Sept 1 1.6h
Sept 5 20.3h
Sept 7 1.0h
Sept 11 19.8h
Sept 13 0.4h
Sept 18 23.9h
Sept 24 23.3h
Sept 26 4.0h
Sept 30 22.7h
Oct 2 3.4h
Oct 6 22.1h
Oct 8 2.8h
Oct 12 21.6h
Oct 14 2.3h
Oct 18 21.0h
Oct 20 1.7h
Oct 24 20.4h
Oct 26 1.2h
Oct 30 19.9h
   

U Cephei

Eclipses of U Cephei are rather inconveniently timed during September and October for observers in the UK.  By early September, mid eclipse is occurring well before the end of evening twilight and so only the later stages of the eclipse can be seen at the start of the night.  From the end of September onwards, eclipses become increasingly better placed in the morning sky.  Initially, only the start of each eclipse is observable, but by mid October mid eclipse is occurring before the onset of morning twilight.

Eclipses last for approx 9 hours. The times shown below are for the primary eclipse mid-point. Eclipses are total, so there is a period of constant brightness around the middle of the eclipse.

Date Mid-Eclipse (UT)
Sept 2 19.2h
Sept 7 18.8h
Sept 12 18.5h
Sept 17 18.2h
   
Sept 30 5.3h
Oct 5 5.0h
Oct 10 4.7h
Oct 15 4.3h
Oct 20 4.0h
Oct 25 3.7h
Oct 30 3.3h
   

 

U Coronae Borealis

Corona Borealis is reasonably well placed in the evening sky ... but is sinking towards the western horizon as the evening progresses.  From late October onwards, it also starts to become visible in the pre-dawn sky.  During the autumn months, the interval of observability is too short for the whole eclipse to be observable in one session.

Eclipses last for approx 12 hours. The times shown below are for the primary eclipse mid-point.  Eclipses are not total, so there is no spell of constant brightness around the middle of the eclipse.

Date Mid-Eclipse (UT)
Sept 1 22.6h
Sept 8 20.3h
Sept 15 18.0h
   
Oct 3 0.3h
Oct 9 22.0h
Oct 16 19.7h
   
Oct 27 4.3h
   

Beta Lyrae

Beta Lyrae remains well placed for observation before midnight, but is becoming low in the sky towards dawn.

Both the deeper primary eclipse and the less deep secondary eclipse can be followed visually.  There is no period of constant brightness between eclipses.

Date Mid-Eclipse (UT)
Aug 31 - Sept 1 primary
Sept 6-7 secondary
Sept 13-14 primary
Sept 19-20 secondary
Sept 26-27 primary
Oct 2-3 secondary
Oct 8-9 primary
Oct 15-16 secondary
Oct 21-22 primary
Oct 27-28 secondary
   

Beta Persei (Algol)

Algol is now much better placed for observation in the night sky.

Eclipses last for approx 10 hours. The times shown below are for the primary eclipse mid-point. Eclipses are only partial, so there is no period of constant brightness around the middle of the eclipse.

Date Mid-Eclipse (UT)
Sept 6 2.4h
Sept 8 23.2h
Sept 11 20.0h
   
Sept 26 4.1h
Sept 29 0.9h
Oct 1 21.7h
Oct 4 18.5h
   
Oct 19 2.6h
Oct 21 23.4h
Oct 24 20.2h
Oct 27 17.1h
   
 

Added by: Tracie Heywood