The list shows occultations of possible double stars during April. Although the main emphasis remains on stars with separations < 2", now that the more detailed lunar limb profile from LOLA is available, some wider pairs are included. Doubles predicted to be occulted by the Moon during April 2018 and visible from parts of Australia or New Zealand are included. The listing is a very abbreviated version of predictions produced by Occult plus an indication of the region of visibility. Observers need to generate their own precise predictions using Occult.

The list below is generated by OCCULT for a 25cm telescope. Some of the events could be beyond the reach of smaller telescopes. Observations of all pairs in the list are highly desirable. Those showing an OCc number have been reported as non-instantaneous at a lunar occultation. Confirmation or otherwise of any double nature is wanted.

*** Kepler stars: the nights on which they are occulted are indicated. Individual Keplers are only shown if they are also a known or possible double. Light curve of occultations of all Kepler stars are desired.

Please send reports of all observations of these stars to Brian Loader at brian.loader@slingshot.co.nz, including any made in earlier months and not so far reported. And of course if you observe a stepped event for a star, which is not a known double, please report this. More details about reporting follow the predictions.

ARCHIVING OCCULTATION LIGHT CURVES

For ALL lunar occultations: single, double and Kepler K2 stars a csv file should be prepared for archiving. This can be done through the OBSERVATIONS EDITOR of OCCULT.

It will be necessary to generate a light curve using LIMOVIE and save or copy its csv file. You will also need to note the time, hh:mm:ss.sss of one frame and the corresponding frame number.

Then in the Observations Editor select the entry for the star and use the menu bar option to create a Light Curve Report. Follow the instructions on the new screen which appears. There is a help file. It is suggested that light curve reports be emailed in batches rather than singly. They are sent directly to Dave Herald from the program.

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 d P    Star  Mag    %         Double details        WDS or   Area of
Apr      No    v    ill      magnitudes sepn    PA°  OCC #    Visibility
 1 r   *** Kepler Stars occulted, light curves are desired    RBTSCM,AkWCh
 1 R    1965  6.5   98- : **  7.3  7.3  0.05" 350.0 OCc1453   RBTS,Ak
   ***  1965 is in the Kepler2 program {ID = 212801410}
 2 r  139898  7.6   96- : AB  7.5  7.5  6.0"  175.1 STF1833   ,I
      139898:  B star is R2059
 3 r   *** Kepler Stars occulted, light curves are desired    RTSCM
 4 r   *** Kepler Stars occulted, light curves are desired    RBTSCM,AkWChI
 4 r  159822  7.8   82- : **  8.6  8.6  0.10"  90.0  OCc  18  ,ChI
 5 r   *** Kepler Stars occulted, light curves are desired    RBTSCM,AkWChI
 5 r  160221  8.5   75- : AB  8.5 12.7  5.6"  252.2  RST3059  RB,Ak
   *** 160221 is in the Kepler2 program {ID = 230879998}
 5 r X 41961  9.6   73- : AB 10.1 11.2  5.2"  207.7  DOO  64  RBTSCM
   *** X 41961 is in the Kepler2 program {ID = 230857836}
 5 r  160317  8.5   73- : AB  8.5 10.7 16.3"  146.7  HJ 4923  M
   *** A light curve is desired as  160317 is in the Kepler2 program {ID = 230875820}
    160317 is double: AB 8.5 10.7 16.3" 146.7
 6 r X146651# 9.1   65- : AB  9.1 10.0  1.2"  298.9  A  2255  RBT,Ak
     X146651:  B star is X 43112
 6 r  160938* 8.7   65- : **  9.1  9.8  0.03" 325.0  OCc1021  RBTSC,Ak
 6 r  160940  9.2   65- : **  9.6  9.6  0.33" 122.0  OCc 525  SCM,WChI
 6 r   *** Kepler Stars occulted, light curves are desired    RBT
 6 r  160993  8.9   64- : AB  8.9 10.9  1.1"   41.0  A  2387  M
 7 r   *** Kepler Stars occulted, light curves are desired    RBTSCM,AkWChI
 7 r  161773  9.0   56- : AB  9.1  9.1  1.7"  316.3  STN  44  BTSCM,AkWChI
       161773:  B star is X159883
 7 R  187349* 6.8   55- : **  8.3  8.3  0.05" 350.0  OCc1554  RBTSC
 7 R  187358* 7.5   55- : **  8.4  8.4  0.05" 350.0  OCc1555  RBTSC
 7 r  187395* 8.9   54- : **  9.7  9.7  0.07" 140.0  OCc1017  M
 8 r  162770  8.3   47- : AB  8.5 10.3  0.10" 339.7  HDS2778  RBTSC,AkWChI
 8 r X 46549  9.5   46- : AB  9.5 11.7  1.2"  295.1  HU  952  M,ChI
 9 r  163472  7.8   38- : **  8.0  8.0  0.10" 350.0  OCc 825  ,WChI
 9 R    2981  5.1   37- : Aab 5.3  7.9  0.10" 106.7  CHR 184  RBTSCM,AkWChI
                        : AB# 5.1  8.5  3.6"  149.1  BU   60  RBTSCM,AkWChI
        2981:  B star is r X174502
 9 R    2987# 4.9   36- : AB  4.97 6.88 1.84" 188.0  SHJ 323° M,WChI
        2987:  B star is X174647
11 r   *** Kepler Stars occulted, light curves are desired    RBTSCM
11 R    3231  7.5   20- : **  8.2  8.2  0.10"  90.0  OCC1614  ,AkWChI
13 r   *** Kepler Stars occulted, light curves are desired    RBTSCM,ChI

19 d   *** Kepler Stars occulted, light curves are desired    TSCM,AkWChI
20 d X 76885# 9.5   22+ :    10.0 10.5  0.20" 170.0  OCC1725  M
20 d   77528  9.5   22+ : AB  8.2 11.3  6.1"  335.0  STF 786  RBT
21 d   *** Kepler Stars occulted, light curves are desired    RBTSCM,Ak
21 d   78592  9.4   31+ : ** 10.0 10.0  0.10"  90.0  OCc 316  ,AkWCh
21 d X  9833* 9.4   33+ : ** 10.8 10.8  0.10" 261.0  OCc 843  RBT
21 d   78762  9.2   33+ : **  8.8 12.0  0.20" 149.0  OCc 325  RB
21 d   78796  8.4   33+ : **  9.3  9.3  0.10" 272.0  OCc 862  R
22 d   79623  7.9   43+ : **  8.7  8.7  0.04" 223.0  OCc1067  ,I
22 d   79686  9.1   44+ : AB  9.6 10.0  0.7"  139.7  HU  645  CM
22 d X 11731  9.4   44+ : ** 11.3 11.3  0.10" 148.0  OCc 815  RBTSCM
23 d   *** Kepler Stars occulted, light curves are desired    RBTSCM,AkWChI
23 d   98107  8.3   55+ : AB  8.5 10.5  0.30" 182.9  HDS1268  RB,Ak
   ***  98107 is in the Kepler2 program {ID = 211861658}
23 d   98132  9.6   55+ : AB  9.4  9.7  0.30"  14.2  OCU 956  TSCM
   ***  98132 is in the Kepler2 program {ID = 211891709}
23 d X 13417  9.4   56+ : AB 10.5 10.8  8.6"   99.0  KU   33  RB
   *** X 13417 is in the Kepler2 program {ID = 211839462}
23 D    1321# 6.9   56+ : AB  7.66 7.57 0.08" 298.7  A  2473° RBTSCM,Ak
23 d   98165  8.2   56+ : AB 12.0 12.1  3.7"   88.1  BRT2392  RBTSCM
       98165: A & B magnitudes not consistent with mag 8.2 star
25 d   *** Kepler Stars occulted, light curves are desired    RBTSCM,AkWCh
25 d   99185  7.9   75+ :  AB 7.7       0.20" 180.0  CHR  31  ,W
   ***  99185 is in the Kepler2 program {ID = 248868565}
26 d   *** Kepler Stars occulted, light curves are desired    RBTS,AkW
27 d   *** Kepler Stars occulted, light curves are desired    RBTSCM,AkWChI
27 d  119382  9.3   92+ : AB  9.4 10.6  7.8"  220.1  AG  177  RBTSC,AkWChI
   *** 119382 is in the Kepler2 program {ID = 201624633}
27 D    1796  7.6   93+ : AC  7.7 12.0  3.7"  338.1  SHJ 146  RBTSCM,AkWCh
   ***   1796 is in the Kepler2 program {ID = 229121547}
29 d  139718  8.1s  99+ : AB  8.2  9.0  4.4"  296.0  STF1799  ,I

30 r    2137  6.6  100- : **  7.2  7.2  0.05" 350.0  OCc1469  TSC,ChI

======================================================================

Visibility codes:
Australia: R Rockhampton, B Brisbane, T Tamworth, S Sydney, C Canberra, M Melbourne  

NZ (following a ,) Ak Auckland, W Wellington, Ch Christchurch, I Invercargill.
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Stars with previous occultation observations: 

#: Observations indicating double - these need further checking
*: Observations not showing double - need confirmation
!: Recent video discoveries - confirmation needed.
?: Uncertain double observation, confirmation or otherwise needed

A WDS number followed by a ° sign indicates the double has a known orbit.

==================================================================

Reporting Your Observations

The most convenient way of reporting is to use Dave Herald's OCCULT which has a Double Star report option in the Observations editor. Before using it, generate a light curve with Limovie and copy to the clip board. Your graph will be attached to the email which you can then send to brian.loader@slingshot.co.nz.

Otherwise in reporting please include your name and positional data as for other occultations reports, also your telescope type and method of observing and timekeeping.

For each event give the star name and the times of each step of the event with the corresponding accuracy. The limb PA, Rv and Cct of the event would also be useful.

In addition to measures of the PA and separation of binary stars, there is also a need for an estimate of the magnitude difference. An estimate of this can be made from the step sizes shown by Limovie data. So if possible a determination should be made of the size of each step together with an estimate of accuracy.

Please also report cases where a double event is predicted but none detected. These are especially likely with stars shown with an OCc designation

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