Measures of the Satellites of Uranus in 1899

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  • Je me permets d'indiquer la circonstance suivante (qui a dCjja CtC mentionnCe dans les A. N. 3388): En SUB des photogrammes mentionnCs j'en posskde encore un de la m&me nCbuleuse obtenu avec une pose de zoh. Ayant dC- t e rmid aussi sur cette plaque I'Cclat de I'Ctoile centrale j'ai r e g le rdsultat suivant:

    Pose entre 22"' et 1 ~ 2 3 " ' Grandeur moyenne = 11d6 Pose loh 8 B = '0.1

    x 2 0 B D = 3.6

    On voit aisement la decroissance de 1'Cclat (relatif) avec la pose. On peut I'expliquer par le fait que, 1'Ctoile centrale Ctant une condensation de la matihre nCbuleuse, elle donne sur les plaques une iniage dont I'intensite s'ac-

    croit plus lentement que celle d'une Ctoile proprement dite. En outre, I'Ctude de mes photographies agrandies permet de conclure que I'etoile centrale, qui a des contours assez irrCguliers et filamenteux, doit &re une mati6re nCbuleuse, peut Stre dans un Ctat tr ts condense, conclusion qui semble &tre en dtsaccord avec les observations de Toulouse.

    Quant au bord extCrieur du sud de la nebuleuse qui a la forme d'un angle de x 2 0 , cela ne doit pas &tre non plus un phCnomhne des derniers temps, vu qu'il a dCjja CtC observe sur un photogramme de 1895 (A. N. 3388 p. 60). On voit aussi, sur cette dernikre photographie, I'Cminence ja I'extrCmitC occidentale de la partie australe de l'anneau, mentionnCe dans les C. R. CXXIX p. 266.

    Tachkent, Observatoire, I 899 Sept. 24.

    Measures of t.he Satellites of Uranus in 1899. By R. G. Aitken.

    The following measures of the satellites of Uranus were made with the 36inch refractor of this observatory. A power of 5 2 0 was used on all nights and each night's observation of a satellite consisted of five settings for po- sition angle followed by five measures of double distance and by five more settings for position angle - distance as well as position angle being measured directly from the center of the planet.

    Estimates of the relative brightness of the two inner satellites were made on each night. Ariel was generally found to be from one-half to one magnitude brighter than Urnbriel, but on two nights, June 1 5 and July 9, it was noted as decidedly the fainter of the two. On both of these nights the conditions were better than the average and yet Ariel was almost at the limit of vision.

    I have compared my resulting positions of the satellites

    are based on his observations with the Washington 26inch equatorial in 1874 and 1875. A glance at the columns p,-p, and so- s, shows that my observations place all four satellites a very little ahead of the tabular positions in their orbits, but that no decided evidence is here afforded for an appreciable deviation from the assumed circular form of any of the orbits.

    As might be expected, the accidental error of measure- ment is greatest in the case of Umbriel. The two large residuals in the distance measures of this satellite on May 1 8 and June 2 are accounted for by my observing notes on those nights which read respectively : swindy and unsteady, Umbriel almost invisible a and s seeing very bad, satellite seen with great difficultya. A similar explanation may be offered for the residuals in distance measures of Oberon on May 14 and June 2 1 , but on June 1 5 and 16, the con-

    with Newcomb's Tables of the Satellites of Uranus') which 1 ditions were good.

    Ar i e l .

    May I I

    18 1 8 '9 19

    ' I

    2 0

    2 0

    2 1 2 7

    June 3 3

    1 5 ' 5 1 6

    I 2 h 4m5 23 1 2 6 2 2 1 2 4 1 1 7 1 2 41 34 ' 3 2 56 '3 3 0 '3 I 7 '3 1 44 1 1 23 8 I I 23 16 I 1 I4 10 1 1 14 zz 1 1 48 58 1 1 49 9 I I 58 5 2

    +3?1 - -

    +2.6 + 3.3

    + 3.5 -

    - -

    +2 .4 +3.2

    + 1.7

    +3.7

    -

    -

    - -0!13 + 0 . 1 5 - -

    - 0 . 2 5

    +0 .13 -0.23

    -

    - -

    +-0.04

    +0.08 -

    -

    W Stratonoff.

    '899

    June 1 6 2 2

    2 2

    28 28 29 29

    I 9 9

    July I

    P. s. rr.

    I Kh59" 0' 10 14 14 1 0 1 4 58 I 0 2 7 25

    I 0 2 7 2 1 10 7 8 10 7 38

    9 36 2 1 9 31 I 4 9 42 46 9 43 4

    Po - P c

    + 2?9 +3.6

    +1 .6

    + 2 . 2

    -

    -

    -

    -

    - -

    +'.I

    +Z. '

    - -

    +0.9

    s - sc

    -0135 -

    1-0.16

    -0.33 -

    - -0.11 -

    - 0.07 + O . I ' I -

    - +0.29 -0.63 -

    ") Washington Observations for I 873, Appendix I.

  • Eastern Time s

    3607 108

    ~ ~~

    '899

    May '9 ' 9 2 0

    2 0

    June 2

    3 3

    '5 ' 5 16 16

    2

    2 2

    2 2

    28 28 29 29

    7 9 9

    July 7

    May 1 1

    14 14 26 26 2 7

    2 7 June 2

    3 3

    1 5

    '5 16

    I 1

    2

    ~~

    P. S. T.

    I 2h45m32s 1 2 45 38 1 1 53 5 I 1 53 7 11 49 '3 1 1 49 36 11 2 7 5 1 1 2 7 36 I ' 2 5 I 0

    I 1 2 5 I 1

    11 34 57 1 1 36 4 9 42 2 1 9 42 48

    10 46 8 1 0 46 13

    9 44 45 9 45 24

    I 0 I 0 2 5 10 I I 38 9 '4 I I 9 '4 2 5

    '899

    June 16 2 1

    2 1

    28 28 29 29

    1 9 9

    July I

    May 11

    I 4 I 4

    I 1

    2 0

    2 0

    2 6

    26 June 4

    4 1 5

    '5 16 16 2 1

    2 1

    28 28 29 29

    July 7 7 9 9

    23 23

    P. S. T.

    12h17m31s 10 56 I 0 10 56 14 1 1 24 I I 1 24 2 7 9 2 0 2 2 9 2 0 43 10 30 30 I 0 31 0 1 0 2 6 59 10 2 7 3

    P o - P c

    + 2 0 1 - 1.5

    + 2.3 +2.9

    -

    -

    -

    - -

    +1.9 + 1.3 - - - 1.7 +3.1 - -

    + 2.7 + 1.4

    +0.9 -

    -

    + 2 . I -

    +0.9 - -

    +r.8

    + 2 . 2

    -

    + 2 . 1

    + 1.4 -

    - + 1 . 2

    - + 1 . 2

    P o - P c

    - -

    + 009 + I . I -

    + 1.5 -1-0.7 -

    - -

    +1.3

    + 1.3 - -

    +o.a +0.4

    -I- 1.5

    + 0.3 +0.6

    +0.9

    -

    -

    -

    -

    - -

    +1.3

    +0.6 + 1.4 t-0.3

    -

    -

    - +0.2 -

    +0.4 -

    00

    20:'IZ - -

    20.30 -

    : 1 9.5 6) 19.82 '9.87

    -

    - -

    19.82 19.82 - -

    '9.72 2 0 . 2 0 - -

    2 0 . 0 5 -

    2 0 . 1 I

    so - sc

    - 0 l r 3 - -

    + O . I O -

    (- 0.95) -

    - 0 . 2 I

    -0.38 - -

    -0.28 -0.05 - -

    -0.06 -0.10 - -

    + O . O I

    +0.19 -

    - -0.23

    -0.29 -0.23

    + O . I 5

    -

    -

    - -

    f O . 0 2

    - -0.14

    + O . I 8

    -

    -

    s - sc

    - 0!09 -0.40 - -

    f o . 1 7

    -0.35

    -0.09 - 0.2 3

    -

    -

    -

    - +0.04 +0.46 - -

    -0.23

    +0.28

    +0.16

    - 0.48

    -0.61 +0.53

    -0.34

    -

    -

    -

    -

    -

    - -

    +o.Ia -

    -0.30 -

    + O . I 2 -

    + 0 . 2 I

    O b e r o n .

    I 3 '3 41 I 3 ' 3 56 13 2 2 0 '3 2 46 I 1 3' 33 I 1 3' 43 1 2 4 2 1 1 2 4 29 1 1 ' 4 33 1 1 ' 4 43 1 2 29 54 1 2 29 56 1 2 32 5 1 1 2 33 '3 I 1 2 1 9 I ' 2 1 I 8 '1 39 30 1 1 39 46 9 3 56 9 4 2 2

    10 53 16 I0 5 5 6 10 4 '5 10 4 25

    8 44 '7 8 44 39

    T i t a n i a. 1 2 5 7 18 1 2 57 32 1 2 2 7 6 1 2 2 1 57 I 1 4 1 0 I1 41 15 I I 5 1 j g I 1 53 2 0 1 2 24 44 1 2 2 5 6 11 49 9 I I 49 '5 1 2 15 26 1 2 '5 54 I 2 I 7 14

    Lick, Observatory, University of California, 1899 Aug. 15. R. G. Aitken.

    Observations of the Satellites of Saturn m a d e with t h e a 6 i n c h r e f r a c t o r of t h e L e a n d e r M c C o r m i c k O b s e r v a t o r y of t h e U n i v e r s i t y o f V i r g i n i a .

    By Omzand Stone.

    Corrections have been applied for refraction. I n the following measures the angles given are each the mean of two comparisons; the distances were obtained

    from measures of double distances.

    1898 Eastern Time P I s I 898 I Eastern Time.1 $J 1 EasternTime E n c e l a d u s - T e t h y s . I oh 4m5 IS

    1 0 33 32 9 4 2 2 9 30 9

    June 30 30

    July I I

    3'3032 318.78 I 13.85 112.51

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