Last updated 14 Sep 2017

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Observing Statistics

The following table summarises time spent observing at Great Shefford each month:

  [A] [B] [C] [D] [E] [F] [G] [H]  [I]

Month

Nights used

Hours spent imaging

Time CCD exposing

Avg. session (hours)

Images acquired

Avg. time between exposures

Average exposure length

Efficiency [G]/[F]

Comments []

2017-Sep 9 43.3 1d 04h 4.8 10361 15s 10s 63.9  
2017-Aug 13 47.5 1d 07h 3.7 9636 18s 12s 65.7  
2017-Jul 14 32.3 21h 01m 2.3 7801 15s 10s 65.1  
2017-Jun 10 35.7 1d 02h 3.6 9606 13s 10s 73.1  
2017-May 14 40.6 1d 04h 2.9 10029 15s 10s 68.8  
2017-Apr 16 63.2 1d 11h 4.0 11558 20s 11s 55.5  
2017-Mar 11 37.8 21h 34m 3.4 6458 21s 12s 57.1  
2017-Feb 6 29.6 16h 40m 4.9 5817 18s 10s 56.4  
2017-Jan 14 80.5 2d 01h 5.8 12123 24s 15s 61.3  
2016 total 139 605.0 15d 06h 4.4 97721 22s 13s 60.4% Available on 366/366 nights.
2016-Dec 9 39.5 1d 04h 4.4 6012 24s 17s 70.0  
2016-Nov 16 79.1 2d 00h 4.9 13204 22s 13s 60.1 Best Nov stats since 2009
2016-Oct 20 88.1 2d 00h 4.4 13099 24s 13s 54.8 Best stats since 2012-Mar
2016-Sep 14 67.0 1d 12h 4.8 10328 23s 12s 53.1  
2016-Aug 14 58.0 1d 14h 4.1 8613 24s 16s 65.2  
2016-Jul 9 31.5 20h 58m 3.5 5275 22s 14s 66.5  
2016-Jun 4 7.8 4h 58m 2.0 1435 20s 12s 63.5 Low pressure stuck over UK, worst stats since 2002
2016-May 14 45.4 1d 03h 3.2 7538 22s 13s 58.6  
2016-Apr 11 50.0 1d 08h 4.5 7910 23s 15s 64.0  
2016-Mar 10 49.3 1d 05h 4.9 8927 20s 12s 59.5  
2016-Feb 9 41.4 1d 02h 4.6 7327 20s 13s 63.2  
2016-Jan 9 48.0 1d 05h 5.3 8053 21s 13s 59.8  
2015 total 131 495.7 12d 07h 3.8 87490 20s 12s 59.6% Available on 363/365 nights.
2015-Dec 8 36.6 20h 13m 4.6 5852 22s 12s 55.4  
2015-Nov 7 27.1 15h 40m 3.9 5500 18s 10s 57.8  
2015-Oct 11 41.9 1d 01h 3.8 7033 21s 13s 59.0  
2015-Sep 18 60.3 1d 10h 3.4 10306 21s 12s 56.7  
2015-Aug 8 24.8 15h 17m 3.1 3570 25s 15s 61.7  
2015-Jul 9 30.2 18h 02m 3.4 4580 24s 14s 59.8  
2015-Jun 9 27.4 17h 16m 3.0 5556 18s 11s 63.1  
2015-May 8 25.0 15h 03m 3.1 4179 22s 13s 60.2  
2015-Apr 16 74.3 1d 17h 4.6 15194 18s 10s 55.5 [2]
2015-Mar 14 52.7 1d 07h 3.8 9364 20s 12s 59.0  
2015-Feb 11 47.8 1d 07h 4.3 8373 21s 13s 64.3  
2015-Jan 12 47.7 1d 08h 4.0 7983 22s 14s 66.4  
2014 total 146 596.8 13d 00h 4.1 84802 25s 13s 52.2% Available on 361/365 nights.
2014-Dec 11 76.2 1d 17h 6.9 12330 22s 12s 54.4  
2014-Nov 9 29.4 16h 15m 3.3 3605 29s 16s 55.4 [2]
2014-Oct 14 55.9 1d 05h 4.0 7864 26s 13s 51.3  
2014-Sep 15 61.7 1d 08h 4.1 8352 27s 14s 51.9  
2014-Aug 10 40.3 20h 28m 4.0 4926 29s 15s 50.8  
2014-July 15 44.6 23h 07m 3.0 6368 25s 13s 51.8  
2014-June 14 33.7 16h 30m 2.4 5259 23s 11s 49.1  
2014-May 11 36.8 17h 34m 3.3 5476 24s 12s 47.8 Worst May conditions since 2003
2014-Apr 14 51.6 1d 01h 3.7 7433 25s 12s 47.9  
2014-Mar 13 71.7 1d 13h 5.5 9392 27s 14s 51.5 [2]
2014-Feb 10 37.4 21h 59m 3.7 5319 25s 15s 58.8 Wettest winter (Dec-Feb) since records began in 1766
2014-Jan 10 57.6 1d 08h 5.8 8478 24s 14s 55.4 Wettest January since records began in 1766
2013 total 147 592.1 13d 12h 4.0 79576 27s 15s 54.7% Available on 354/365 nights.
Worst full year stats 2003-2013
2013-Dec 12 56.8 1d 08h 4.7 7474 27s 15s 56.0  
2013-Nov 11 48.9 1d 02h 4.4 5923 30s 16s 53.4  
2013-Oct 15 70.4 1d 11h 4.7 9908 26s 13s 49.2  
2013-Sep 15 62.5 1d 06h 4.2 8650 26s 12s 47.2  
2013-Aug 17 58.5 1d 10h 3.4 7429 28s 17s 58.4  
2013-Jul 15 44.3 1d 03h 3.0 5884 27s 17s 61.9  
2013-Jun 9 33.4 18h 12m 3.7 3850 31s 17s 54.6 [2]
2013-May 12 44.4 1d 01h 3.7 6681 24s 13s 55.5 [8]
2013-Apr 17 69.5 1d 15h 4.1 10750 23s 13s 56.0 [2]
2013-Mar 7 32.1 17h 20m 4.6 4297 27s 15s 54.0 Worst Mar since 2002
2013-Feb 10 47.2 1d 02h 4.7 5580 30s 17s 56.0 Worst Feb since 2002 other than 2011
2013-Jan 7 24.0 14h 19m 3.4 3150 27s 16s 59.6 Worst Jan since 2002
2012 total 161 740.5 15d 19h 4.6 101543 26s 13s 51.2% Available on 334/366 nights.
Wettest year since records began in 1910 for England
2012-Dec 14 55.0 1d 05h 3.9 9396 21s 10s 52.7  
2012-Nov 13 58.1 1d 05h 4.5 9150 23s 11s 50.1  
2012-Oct 12 41.7 18h 08m 3.5 5657 27s 12s 43.5  
2012-Sep 20 83.3 1d 21h 4.2 9882 30s 16s 53.8  
2012-Aug 13 40.8 20h 28m 3.1 4039 36s 18s 50.2 [1] Poor weather continues. Jun-Jul-Aug wettest for 100 years in England
2012-Jul 9 30.1 16h 12m 3.3 3882 28s 15s 53.9 [2] Poor weather continued until 16th July
2012-Jun 7 18.1 9h 42m 2.6 3153 21s 11s 53.5 [9] V. poor weather. Equal-wettest June in England since records began in 1766
2012-May 13 55.5 1d 05h 4.3 7475 27s 14s 52.6 [4]
2012-Apr 11 50.1 1d 03h 4.6 6824 26s 14s 54.1 Worst Apr since operations began in 2002  [3]
2012-Mar 19 113.3 2d 09h 6.0 16498 25s 12s 50.4% [2]
2012-Feb 10 85.1 1d 22h 8.5 9833 31s 17s 53.9% [8]
2012-Jan 20 109.3 2d 05h 5.5 15754 25s 12s 48.1% [2]
2011 total 157 714.2 16d 15h 4.5 96026 27s 15s 55.8% Available on 306/365 nights
2011-Dec 14 80.8 2d 00h 5.8 10320 28s 17s 59.5% [5]
2011-Nov 9 51.3 1d 07h 5.7 5868 31s 19s 60.9% [5]
2011-Oct 6 40.1 18h 58m 6.7 3622 40s 19s 47.3% [16]
2011-Sep 17 85.3 1d 23h 5.0 10594 29s 16s 54.7% [5]
2011-Aug 11 36.4 20h 43m 3.3 3845 34s 19s 59.9% [3]
Worst Aug since 2002
2011-Jul 13 34.3 21h 18m 2.6 3978 31s 19s 62.2%  
2011-Jun 18 61.2 1d 08h 3.4 8852 25s 13s 52.9%  
2011-May 16 67.5 1d 14h 4.2 8659 28s 16s 56.9%  
2011-Apr 21 107.4 2d 12h 5.1 15508 25s 14s 55.4% [3]
 
2011-Mar 16 81.8 1d 15h 5.1 14722 20s 10s 48.2% [6]
 
2011-Feb 7 26.0 15h 06m 3.7 4067 23s 13s 58.1% [6]
Worst Feb since 2002
2011-Jan 9 42.1 1d 03h 4.7 5991 25s 16s 63.9% [5]
Worst Jan since 2002
2010 total 169 702.3 15d 15h 4.2 112657 22s 12s 53.4% Available on 347/365 nights
2010-Dec 10 48.9 1d 03h 4.9 7615 23s 13s 55.6% Worst Dec since 2002
2010-Nov 13 41.7 17h 02m 3.2 6473 23s 9s 40.9% Unusually poor conditions for Nov, worst since 2003
2010-Oct 17 69.3 1d 14h 4.1 11415 22s 12s 54.6%  
2010-Sep 17 85.4 1d 13h 5.0 12441 25s 11s 43.7%  
2010-Aug 14 61.5 1d 10h 4.4 6473 34s 19s 55.9%  
2010-Jul 10 21.3 12h 36m 2.1 3074 25s 15s 59.4% Worst conditions since 2007-Jun
2010-Jun 17 53.7 1d 06h 3.2 8089 24s 13s 55.1%  
2010-May 14 56.9 1d 04h 4.1 11618 18s 9s 48.6%  
2010-Apr 19 70.6 1d 11h 3.7 14279 18s 9s 48.9%  
2010-Mar 14 77.6 1d 16h 5.5 11501 24s 13s 52.1%  
2010-Feb 12 50.9 1d 09h 4.2 8347 22s 14s 64.6%  
2010-Jan 12 64.7 1d 20h 5.4 11332 21s 14s 67.7%  
2009 total 202 938.2 24d 00h 4.6 148361 23s 14s 61.4% Available on 353/365 nights
2009-Dec 15 77.6 2d 04h 5.2 11455 24s 8s 66.5%  
2009-Nov 18 87.2 1d 20h 4.8 15481 20s 10s 50.8%  
2009-Oct 13 69.9 1d 20h 5.4 15994 16s 10s 62.8%  
2009-Sep 19 103.6 2d 11h 5.5 13615 27s 15s 56.6%  
2009-Aug 18 96.3 2d 05h 5.3 18278 19s 11s 55.5%  
2009-Jul 16 48.4 1d 14h 3.0 5241 33s 26s 78.7%  
2009-Jun 18 49.0 1d 07h 2.7 9473 19s 12s 64.1%  
2009-May 23 84.0 2d 04h 3.7 11327 27s 17s 62.3%  
2009-Apr 17 71.8 2d 03h 4.2 10405 25s 18s 71.2%  
2009-Mar 19 114.5 2d 16h 6.0 19191 21s 12s 56.2%  
2009-Feb 12 54.6 1d 09h 4.5 6351 31s 19s 61.1%  
2009-Jan 14 81.4 2d 05h 5.8 11550 25s 17s 65.6%  
2008 total 171 753.8 21d 13h 4.4 91715 30s 20s 68.6% Available on 348/366 nights
2008-Dec 15 76.4 2d 02h 5.1 9121 30s 20s 65.7%  
2008-Nov 11 52.7 1d 11h 4.8 5608 34s 23s 66.8%  
2008-Oct 20 125.3 3d 22h 6.3 14971 30s 23s 75.0%  
2008-Sep 14 70.6 1d 21h 5.0 7498 34s 22s 63.5%  
2008-Aug 14 50.6 1d 10h 3.6 5946 31s 20s 66.5%  
2008-Jul 13 25.0 17h 24m 1.9 2672 34s 23s 69.7%  
2008-Jun 16 47.4 1d 10h 3.0 7321 23s 16s 70.7%  
2008-May 10 30.2 22h 21m 3.0 4086 27s 20s 74.0%  
2008-Apr 15 62.2 1d 19h 4.1 8110 28s 19s 68.7%  
2008-Mar 16 58.7 1d 10h 3.7 6779 31s 18s 58.6% Out of operation 7 nights
2008-Feb 15 101.8 2d 22h 6.8 13810 27s 18s 69.2%  
2008-Jan 12 53.0 1d 14h 4.4 5793 33s 24s 72.7%  
2007 total 178 819.7 22d 03h 4.6 92025 32s 21s 64.8% Available on 347/365 nights
2007-Dec 15 82.5 2d 09h 5.5 7034 42s 29s 69.2%  
2007-Nov 14 72.9 2d 00h 5.2 9979 26s 17s 66.1%  
2007-Oct 13 52.5 1d 09h 4.0 6206 30s 19s 62.5%  
2007-Sep 17 96.3 2d 13h 5.7 10615 33s 21s 63.6%  
2007-Aug 15 71.0 1d 21h 4.7 7286 35s 22s 63.8%  
2007-Jul 16 49.9 23h 38m 3.1 4578 39s 19s 47.4% Poor weather continued, flooding on 20 July.
2007-Jun 8 20.4 12h 34m 2.5 3292 22s 14s 61.8%

Very poor weather across the UK in May & especially June, which was the cloudiest month since 2002 Dec.

2007-May 14 40.8 1d 03h 2.9 4343 34s 22s 65.5%  
2007-Apr 20 98.7 2d 13h 4.9 12123 29s 18s 61.6%  
2007-Mar 16 98.1 2d 12h 6.1 12030 29s 18s 61.6%  
2007-Feb 12 52.4 1d 14h 4.4 5884 32s 24s 73.4%  
2007-Jan 18 84.3 2d 16h 4.7 8655 35s 26s 75.4%  
2006 total 169 798.5 21d 03h 4.7 80515 36s 23s 63.5% Available on 350/365 nights
2006-Dec 10 59.2 1d 20h 5.9 6583 32s 24s 74.3%  
2006-Nov 16 105.1 2d 15h 6.6 9553 40s 24s 59.6%  
2006-Oct 14 94.0 2d 12h 6.7 8989 38s 24s 64.2%  
2006-Sep 14 70.2 1d 17h 5.0 7805 32s 19s 58.4%  
2006-Aug 16 51.4 1d 07h 3.2 4282 43s 26s 60.7%  
2006-Jul 16 61.6 1d 18h 3.9 5680 39s 27s 68.0%  
2006-Jun 13 37.3 23h 49h 2.9 4473 30s 19s 63.9%  
2006-May 13 38.9 22h 00h 3.0 4693 30s 17s 56.5%  
2006-Apr 19 87.9 2d 12h 4.6 8056 39s 27s 68.2%  
2006-Mar 11 67.0 1d 18h 6.1 6112 39s 25s 62.8%  
2006-Feb 14 53.5 1d 09h 3.8 5520 35s 22s 62.0%  
2006-Jan 13 72.3 1d 21h 5.6 8769 30s 18s 62.3%  
2005 total 181 841.5 18d 06h 4.7 69239 44s 23s 52.1% Available on 332/365 nights
2005-Dec 17 101.5 2d 16h 6.0 9124 40s 25s 62.9%  
2005-Nov 16 112.3 3d 03h 7.0 11225 36s 24s 66.8%  
2005-Oct 14 60.5 1d 15h 4.3 6792 32s 21s 64.5%  
2005-Sep 12 (9th-30th) 50.0 1d 06h 4.2 4297 42s 26s 63.5% Out of operation from 15Aug-09Sep (CCD being upgraded)
2005-Aug 11 (1st-14th) 42.1 19h 11m 3.8 2800 54s 25s 45.6%
2005-Jul 18 61.0 1d 01h 3.4 4267 51s 21s 40.3%  
2005-Jun 11 35.5 15h 40m 3.2 2802 46s 20s 44.2% Out of operation 7 nights (Telescope being upgraded)
2005-May 21 66.6 1d 07h 3.2 5787 41s 19s 45.8%  
2005-Apr 18 79.7 1d 14h 4.4 6014 48s 23s 48.2%  
2005-Mar 15 74.2 1d 08h 4.9 5281 51s 22s 43.4%  
2005-Feb 13 55.0 1d 00h 4.2 3604 55s 24s 43.7%  
2005-Jan 15 103.2 1d 21h 6.9 7246 51s 22s 43.4%  
2004 total 182 774.6 12d 15h 4.3 53725 52s 20s 39.1% Available on 361/366 nights
2004-Dec 17 97.1 1d 13h 5.7 7005 50s 19s 38.4%  
2004-Nov 14 62.5 1d 03h 4.5 4235 53s 23s 43.9%  
2004-Oct 15 57.6 1d 01h 3.8 4226 49s 22s 44.5%  
2004-Sep 17 93.4 1d 18h 5.5 7402 45s 21s 46.0%  
2004-Aug 18 67.6 1d 06h 3.8 5184 47s 21s 44.8%  
2004-Jul 15 30.4 14h 43m 2.0 2173 50s 24s 48.5%  
2004-Jun 17 41.4 17h 38m 2.4 3395 44s 19s 42.6%  
2004-May 13 46.0 18h 05m 3.5 3872 43s 17s 39.3%  
2004-Apr 13 63.2 21h 37m 4.9 4964 46s 16s 34.2%  
2004-Mar 16 70.3 23h 31m 4.4 4492 56s 19s 33.5%  
2004-Feb 16 75.7 1d 00h 4.7 3592 1m16s 24s 32.0%  
2004-Jan 11 69.6 19h 47m 6.3 3185 1m19s 22s 28.4%  
2003 total 183 701.1 7d 13h 3.8 28090 1m30s 23s 25.8% Available on 347/365 nights
2003-Dec 13 83.6 1d 01h 6.4 3965 1m16s 23s 30.8%  
2003-Nov 10 36.2 8h 48m 3.6 1539 1m25s 21s 24.3%  
2003-Oct 15 77.7 23h 46m 5.2 3713 1m15s 23s 30.6%  
2003-Sep 23 110.7 1d 03h 4.8 4334 1m32s 22s 24.4%  
2003-Aug 18 61.6 16h 22m 3.4 2146 1m43s 27s 26.6%  
2003-Jul 16 42.7 9h 39m 2.7 1619 1m35s 21s 22.6%  
2003-Jun 7 20.9 7h 06m 3.0 967 1m18s 26s 34.0%  
2003-May 13 30.9 8h 47m 2.4 1242 1m29s 25s 28.5%  
2003-Apr 17 52.5 12h 03m 3.1 1992 1m35s 22s 23.0%  
2003-Mar 18 68.9 13h 35m 3.8 2674 1m33s 18s 19.7%  
2003-Feb 16 58.5 13h 31m 3.7 1983 1m46s 25s 23.1%  
2003-Jan 17 57.0 14h 37m 3.4 1916 1m47s 27s 25.7%  
2002 total 87 164.3 1d 02h 1.9 3042 3m14s 31s 15.8% Available on 230/365 nights
2002-Dec 5 11.6 2h 38m 2.3 323 2m09s 29s 22.8%  
2002-Nov 13 16.3 3h 27m 1.3 419 2m20s 30s 21.2%  
2002-Oct 9 35.6 4h 03m 4.0 506 4m13s 29s 11.4%  
2002-Sep 15 24.1 4h 14m 1.6 509 2m51s 30s 17.6%  
2002-Aug 18 34.7 5h 05m 1.9 645 3m14s 28s 14.7%  
2002-Jul 15 26.0 3h 40m 1.7 411 3m48s 32s 14.1%  
2002-Jun 8 12.7 2h 11m 1.6 169 4m30s 47s 17.3%  
2002-May 4 3.4 35m 0.8 60 3m21s 36s 17.7% First light 16th May

[A] A night is counted as being used if at least one image is obtained from dusk until dawn, the date being taken as the date at dusk.

[B] Hours spent imaging or the total session time is taken as the number of hours between the first  and the last image obtained in each session, so doesn't count waiting for the CCD to cool down, focussing, warming the CCD up at the end of each session and other non-productive activities...

[C]Time CCD exposing is the length of time the CCD shutter is open, actively imaging objects

[D] Average session length is (Hours spent imaging / Nights used) or [B]/[C]

[F] Avg. time between exposures is the average time between the start of one exposure and the start of the next exposure and is affected by CCD image download times, clouds interrupting observing, human 'thinking' time etc.
[G] Average exposure length = (Time CCD exposing / Images acquired) = [C] / [E]
[H] Efficiency [G]/[F] shows how much of the time spent in a session was used actually collecting light and is calculated as the percentage [G]/[F] or [C]/[B]. Note the increase due to the CCD upgrade shortening image download times between August and September 2005.
[I] Comments Numbers enclosed in [] indicate the number of nights spent away from the observatory during the month and therefore not available for observing.

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