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Flamsteed's observations of the Jovian Satellites 1689-1719

Page under construction

 

Dif + = Oct clock ahead of arc house; - = Oct behind arc house
n = note in observing book

Line 1: there are two entries and in both corrected times 6 seconds less than apographa
Line 6: Apographa has observed time as 11 23 10
Line 9: 1725 version has transcription errors 
Line 12. Observing book 'corrections' labeled as 'camera'. Time difference for others is 03 35, not 03 36
Line 13. Halley has twice mistranscribed 6 as 0


 Date Obs Bk. Apog 1725 1725 1712 1712 A Dif


+ 






1 04 Oct 1689 08 11 00 08 07 46 n/p n/p 08 11 00 08 07 40 ✓ +02 13
2 17 Oct  09 08 40 09 22 45 09 08 40 09 22 45 09 08 40 09 22 45 x
3 03 Nov 07 11 20 07 23 45 07 11 20 07 23 45 07 11 20 07 23 45 x
4 04 Jan 1690 05 49 14 05 50 42 05 49 14 05 50 42 05 49 14 05 50 42 ✓ - 02 48
5 10 Jun  14 54 08 14 54 08 14 58 10 14 54 08 14 58 10 14 54 08 ✓ trimmed
6 20 Aug  11 23 09 11 21 26 11 23 10 11 21 26 11 23 10 11 21 26 ✓ - 13 29
7 07 Oct 08 43 10 08 40 54 08 43 10 08 40 54 08 43 10 08 40 54 ✓ - 09 20
8 30 Oct 07 30 46 07 26 53 07 30 46 07 26 53 07 30 46 07 26 53 ✓ - 08 16
9 22 Nov 08 41 24 08 32 49 08 41 24 08 32 39 08 41 24 08 32 49 ✓ - 05 04n
10 29 Nov 11 03 28 10 56 48 11 03 28 10 46 48 11 03 28 10 56 48 ✓ +00 10
11 02 Jan 1691 06 49 24 06 46 28 06 49 24 06 46 28 06 49 24 06 46 28 ✓ +00 20
12 07 Jan 09 16 04 09 14 34 09 16 04 09 14 34 09 16 04 09 14 34 ✓ +03 36
13 03 Feb* 06 42 06 06 33 26 06 42 06 06 33 26 06 42 00 06 33 20 ✓ - 05 20
14 08 Feb 05 55 44 05 50 11 05 55 44 05 50 11 05 55 44 05 50 11 ✓ - 03 44
15 09 Feb 07 15 33 07 10 34 07 15 33 07 10 04 07 15 33 07 10 04 ✓ - 03 49
16 09 Aug



11 11 14 11 04 32 ✓
17 23 Aug







18 25 Aug







19 29 Sep







20 25 Nov
06 47 48

06 56 00 06 47 48

21 27 Nov
07 05 44

07 09 37 07 05 44

22 02 Mar 1692







23 04 Aug







24 29 Sep







25 16 Jan 1693







apog entres of corrected time not lited 29 septt 1692, 4 oct 1694

Line 1, not included in the 1725 volume


 Date Oct Clock (a) Obs Bk. (b) Apog (c) a-b b-c


(A. Hse Clock) Corrected time
Clock
error
1 04 Oct 1689 x 08 11 00 08 07 46
+03 14
2 17 Oct  x 09 08 40 09 22 45
- 14 05
3 03 Nov x 07 11 20 07 23 45
- 12 25
4 04 Jan 1690 05 46 26 05 49 14 05 50 42 - 02 48 - 01 28
5 10 Jun           38 14 54 10 14 54 08 trimmed +00 02
6 20 Aug      09 40 11 23 09 11 21 26 - 13 29 +01 43
7 07 Oct     33 56 08 43 10 08 40 54 - 09 14 +02 16
8 30 Oct 07 22 30 07 30 46 07 26 53 - 08 16 +03 53
9 22 Nov 08 36 20 08 41 24 08 32 49 - 05 04n +08 35
10 29 Nov      03 38  11 03 28 10 56 48 +00 10 +06 40
11 02 Jan 1691      49 44 06 49 24 06 46 28 +00 20 +02 56
12 07 Jan      19 40 09 16 04 09 14 34 +03 36 +01 30
13 03 Feb* 06 36 46 06 42 06 06 33 26 - 05 20 +08 42
14 08 Feb 05 52 00 05 55 44 05 50 11 - 03 44 +05 33
15 09 Feb 07 11 44 07 15 33 07 10 34 - 03 49 +04 59

a

 

Although the corrected times agree in the above table, that is solely because Halley used the reduced figures that were in the copy of the apographa that he was using. With many of the later observations, the calculation of the corrected time was not included in the apographa. When this was the case Halley had to calculate the correct figure himself. But wheras all the satellite entries in the 1712 edition have a figure for the corrected time. This is not the case in the 1725 edition, where in many cases, if they weren't in the apographa, then there was no corrected entry in the published edition. Sometimes however, a figure was provided. But the that provided by Flamsteed always(?) differed from that worked out by Halley.

For example one of the observed times on 10 June 1700 was 15 32 58. Flamsteed's corrected figure is 15 26 53, whereas Halley's is 15 31 28. Likewise, on 31 August 1700, the one of the observed times was 10 58 12. Flamsteed's corrected time is 11 02 52 and Halley's is 11 02 37.

But what were they correcting to? Apparent time of corrected clock time? As mentioned earlier, in the apographa, only the first three pages of the first volume (ie up until 4 October 1689) have a heading in the second column (Tempora correcta) . None of the pages of the second volume have the heading filled in. But in the third volume (which covers the period 11 Jan 1704 to 12 Nov 1715), the words Tempora Correct appear at the top of the second column on every page

 

1712 missing 25 Oct 1691. 7 Mar 1692, 25 Feb 1694, transcription error in obs time in 1725 edition

 

28 Oct 1701 the same

11 Feb & 2 Mar 1705 observed times can't be reconciled. Halley's figures seem entirely spurious


 Date Obs time 1725 correction (a) 1712 Correction (b) difference (a-b)
1 27 Dec 1691 08 56 33 08 43  08 43 18 - 00 18
2 23 Oct 1695 17 28 37 17 23 17 23 37 - 00 37
3 10 Jun 1700 15 32 58 15 26 53 15 31 28 - 04 35
4 31 Aug 10 58 12 11 02 52 11 02 37 +00 15
5 01 Dec 04 45 15 04 49 57 04 50 00 - 00 03
6 07 May 1701 15 08 50 15 01 05 15 01 00 +00 05
7 15 Jun 15 30 06 15 20 46 13 20 56 - 00 10
8 31 July 10 16 34 10 06 34 10 06 30 +00 04
9 07 Auga 15 49 09 15 33 54 15 33 52 +00 02
10 28 Sep 10 29 18 10 24 43 10 24 28 +00 15
11 20 Oct 1702 08 28 33 08 31 03 08 30 58 +00 05
12 16 Nov 05 57 25 05 55 05 05 56 45 - 01 40
13 22 Sep 1703 08 09 13 08 09 43 08 09 33 +00 10

a) some of the observed and corrected times in the 1725 edition are incorrect by an hour p.421 (not corrected in the erata)