T h e B r it is h A s t r o n o m ic a l A s s o c ia t io n

Transcription

1 T h e B r it is h A s t r o n o m ic a l A s s o c ia t io n VARIABLE STAR SECTION CIRCULAR SEPT-OCT Head Office: Burlington House, Piccadilly, London \V 1V ONL. Telephone

2 S E C TIO N O F F IC E R S : D i r e c t o r D.R.B. S a w, 1 2 T a y l o r R o a d, A y le s b u r y, B u c k s. HP21 8DR T e l : A y le s b u r y ( ) A s s i s t a n t D i r e c t o r S.R. D u n lo p, S t o c k s L a n e, E a s t W i t t e r i n g, n r C h i c h e s t e r, W e s t S u s s e x P ΘΝΤ P ro g ra m m e S e c r e t a r i e s : T e l : B r a c k le s h a ffl B a y ( ) M a in S e c r e t a r y G.A.V. C o a d y, 15 C e d a r C lo s e, M a r k e t D e e p in g, P e t e r b o r o u g h P E 6 8BD T e l : M a r k e t D e e p in g ( ; B i n o c u l a r M.D. T a y l o r, 1 7 C r o s s L a n e, W a k e f i e l d, W est S e c r e t a r y Y o r k s h i r e WF2 8DA T e l : W a k e f ie ld ( ) A s s i s t a n t J. T o o n e, 2 H i l t o n C r e s c e n t, B o o th s to w n, B i n o c u l a r W o r s le y, M a n c h e s te r M 28 4FY S e c r e t a r y T e l : E c l i p s i n g B i n a r y J. E. I s l e s, F l a t 5, 21 B is h o p s B r id a e R o a d, S e c r e t a r y L o n d o n W2 6BA T e l : N o v a /S u p e r n o v a G.M. H u r s t, 1 W h e r n s id e, M an o r P a r k, S e a r c h S e c r e t a r y W e llin g b o r o u g h, N o r t h a n t s. NN8 3OQ T e l : W e llin g b o r o u g h ( ) C h a r t S e c r e t a r y J. P a r k in s o n, 2 8 B a n k s R o a d, B o l c a r, H u d d e r s f i e l d, W e s t Y o r k s h i r e HD7 4LX C IRCULARS T e l : H u d d e r s f i e l d ( ) C h a r g e s : U.K. & E i r e - 2 f o r C i r c u l a r s and 1 i g h t - c u r v e s O t h e r c o u n t r i e s 3 S en d p a y m e n ts (m ade o u t t o t h e B A A ), a n d m a t e r i a l f o r i n c l u s i o n t o S to rm D u n lo p. CHARTS C h a r g e s : M a in P ro g ra m m e - SAE p lu s 2Op p e r s t a r (4 s h e e t s ) A l l o t h e r p ro g ra m m e s SAE p lu s 5p p e r s t a r (1 s h e e t ) R e q u e s ts s h o u ld b e s e n t t o J o h n P a r k in s o n.

3 E D ITO R IA L T h is is s u e o f th e C i r c u l a r i s a lm o s t e n t i r e l y d e v o te d t o a f u l l l i s t i n g o f th e E c li p s in g B in a r y P ro g ra m m e. A lth o u g h t h i s may d i s a p p o in t m em bers who lo o k f o r v a r ie d ite m s i n th e s e p u b l i c a t i o n s, i t has b e e n t h o u g h t b e s t t o g iv e a l l th e d e t a i l s i n a s in g le is s u e w h ic h may be u s e d f o r f u t u r e r e f e r e n c e, r a t h e r th a n d i v i d i n g th e l i s t i n g b e tw e e n tw o o r m ore is s u e s. The n e x t C i r c u l a r (N o. 5 6 ), s c h e d u le d t o be is s u e d i n D ecem ber 1983 w i l l r e v e r t t o th e u s u a l f o r m a t, and c o n t a in f u r t h e r l i g h t - c u r v e s. The E c lip s in g B in a r y Program m e i s a v e r y im p o r t a n t p a r t o f th e V a r ia b le S t a r S e c t io n 's o v e r a l l p ro gra m m e o f o b s e r v a t io n. F o r some unknow n re a s o n s i t h a s n e v e r seem ed t o a p p e a l v e r y g r e a t l y t o a m a te u rs i n th e U n it e d K in g d o m, a lth o u g h o b s e r v e r s i n many o t h e r E u ro p e a n c o u n t r ie s h a v e f r e q u e n t l y made i t t h e i r p r im a r y f i e l d o f i n t e r e s t. We hope t h a t w i t h th e c h a n g e s i n th e p ro g ra m m e a n d th e a v a i l a b i l i t y o f p r e d i c t i o n s, many m ore m em bers w i l l ta k e up t h i s p a r t i c u l a r s t u d y. A m a te u r o b s e r v a tio n s c a n m o s t c e r t a i n l y g iv e m o s t v a lu a b le in f o r m a t io n a b o u t th e s e o b je c t s. SUBSCRIPTIONS - A CORRECTION We w o u ld l i k e t o p o in t o u t t o o u r m em bers i n E ir e t h a t t h e i r s u b s c r ip t i o n r a t e i s th e same as t h a t f o r th e U n it e d K in g d o m, n a m e ly p e r annum. We a p o lo g iz e f o r t h e f a c t t h a t we made i t seem as i f i t s h o u ld be h ig h e r. VERANDERLICHE STERNE (VARIABLE STARS) b y C. HOFFMEISTER M em bers w i l l d o u b tle s s be i n t e r e s t e d t o know t h a t th e s e c o n d e d i t i o n o f t h i s ' c l a s s i c ' w o rk i s i n an a d v a n c e d s t a g e, and t h a t b o th Germ an and E n g lis h v e r s io n s a r e t o be p u b lis h e d. The new e d i t i o n h a s b e e n p r e p a r e d b y D rs W e n ze l and R i c h t e r, o f S o n n e b e rg, who saw th e o r i g i n a l e d i t i o n t h r o u g h th e p r e s s a f t e r H o f f m e i s t e r ' s d e a th i n The E n g lis h t r a n s l a t i o n i s b e in g made b y S to rm D u n lo p. P u b lic a t io n may be e x p e c te d to w a r d s th e e n d o f , b u t f u r t h e r d e t a i l s w i l l be g iv e n when a v a i l a b l e. EPSILON AURIGAE I n IBVS 2371 f o u r J a p a n e s e o b s e r v e r s p r e s e n t t h e i r p. e. l i g h t - c u r v e s o f th e e c l ip s e in g r e s s o v e r th e p e r io d 1982 O c to b e r t o 1983 M a rc h. O b s e r v a tio n s w e re made i n U, B and V r e g io n s and s u b s e q u e n tly re d u c e d b y c o m p u te r. The t e le s c o p e s u s e d w e re 200-mm r e f l e c t o r, 300-mm r e f l e c t o r and 200-mm r e f r a c t o r [ s i c! ]. U, B and V mags a t m inim um a r e e s t im a te d t o be 4.7 4, and r e s p e c t i v e l y. E po ch o f s e c o n d c o n t a c t i s e s t im a te d a t a ro u n d JD , some 9 d a y s e a r l i e r th a n p r e d ic t e d b y G y ld e n k e rn e i n ORBITAL PERIODS FOR SOME CATACLYSMIC BINARIES I n IBVS , S h a f t e r p r e s e n ts p e r io d s f o r 6 c a t a c ly s m ic s y s te m s, some o f w h ic h a r e o f i n t e r e s t t o a m a te u r s. T h e se a r e : V794 A q l = ( a p p r o x.) SY Cnc = CM D e l = V360 Oph = TW V i r = ( 6 6 ) VW V u l =

4 ECLIPSING BINARY PROGRAMME Predictions are now available for all objects on the EBP. There are four sets of predictions, as described in the J ournal for 1982 February, and details of the stars included are given in this Circular. List A contains objects 8-0m or brighter at maximum, whose minima should be observable in a single night. Several stars have been added to this list since the preliminary details given in VbSC 48. List B contains similar objects with maximum magnitude between 8 and 10. List C contains objects for which observations made on more than one night need to be combined in order to derive a timing for minimum - because either the eclipse is too long (up to 48 hours), or the object is too far south of the equator (down to -18 ). List D contains objects with very long eclipses. in conjunction with List E (vssc 53), these include all catalogued eclipsing binaries north of -18 which are brighter than 10m at maximum and can be observed visually (amplitude at least 0-4m). I hope these lists will be a useful reference for all observers even though they may not participate in the EBP. For each object, the first line gives the name, approximate range and type. The second line gives its Ra and l)ec for , the duration of minimum as a fraction of the period, the JD of a minimum and the period. If a third line is present there are non-linear terms in the catalogue elements used in the predictions (see next paragraph;. If secondary 'minimum is at least 0*3m deep, a second entry follows giving the magnitude of Min II and prediction elements. For the interest of members with microcomputers who are interested in producing their own predictions, the non-linear terms work as follows. Let T be the given JD of minimum, P the period and A, B, C, D, E, F the six values given on line 3. The time of the n th following minimum is given by?, T + np + A sin (nc - D) + B sin 2(nC + D) + η E + n 9F. Most members can ignore the elements as everything, including light-time corrections, is taken care of in the predictions. The predictions for lists A and B give, for each eclipse observable from the British Isles, the times of beginning, middle and end, and the light-time correction to be added to the observed time of minimum to obtain the heliocentric time. For List D there is a row for each star, showing an asterisk for each date (12h GMAT) when the object is in eclipse. For List C the predictions are less straightforward, so here is an example. For 1983 Nov 1 a minimum of AI Cep is listed as follows: Mid Eclipse 1d 2 -Oh Visible from 5*6h to 14-8h Eclipse Limits Od 13"5h, 1d 15 O h LTC 3m Note that, whereas mid eclipse and eclipse limits are rounded to the nearest half-hour (a precaution against bias, as also in lists A and B), the limits of visibility (star at least 5 above horizon and sun at least 10 below horizon) are correct to the nearest 0-1h. AI Cep is observable between about and GMAT on Nov 1, and at similar times on adjacent nights. Nov Od 2

5 means Oct 31d, so the eclipse starts on Oct 31d at about 13.30, and finishes on Nov 1d at about It follows that AI Cep can actually be observed in eclipse on Oct 31 from to 14.48, and on Nov 1 from to On Oct 31 the top of the falling branch will be seen. Mid eclipse occurs in daylight but most of the rising branch can be seen on Nov 1. Observations made on these two nights (.or indeed on other nights when the object is again in eclipse) may be combined to yield a timing. Three minutes should then be added to the observed time of minimum to obtain the heliocentric time. It may be seen that in order to find out which stars on list o are observable in eclipse on a given night it is necessary to look at the predictions not only for that night but also for the preceding and following nights. Incidentally, AI Cep is o f Beta lyrae type (continuously changing brightness) and the catalogue does not give a duration of minimum. Tor objects of this type and of W Ursae Majoris type (EB and EW), the predictions assume an eclipse duration of Ο 25 of the period as most of the light variation will occur during this interval, in the case just discussed, the observer might well decide to start observation on Oct 31 somewhat earlier than Tor stars of type EA (Algol) or E (unknown subclass), if the catalogue does not give the duration of eclipse the predictions assume the typical value of 0 2 of the period. Observers should report to me any apparent error in the predictions, whether in the duration of eclipse, the time of mid-eclipse, or the observability of the minimum. A lot of trouble has been taken by Dr Owen and me to get these predictions into a convenient format, but only experience will show whether we have really produced predictions in the form most suitable for observers; and there are bound to be inadequacies in the data we are working from (1969 GCVS and Supplements up to 1976). Observers who experience difficulties should not despair but write to me about it. Guidance on frequency of observation, reductions etc is given in the 1982 Tebruary Journal (offprints available from me). In deciding which objects to attempt, observers should remember that objects on lists A, B and D with large amplitudes are the easiest to observe, and so are the most suitable for beginners. Little is known about most objects on lists C and E (unknown period etc), so these will be the most useful systems to attempt despite the difficulties of observation, provided observations are persued with diligence to ensure adequate coverage. Objects with small amplitudes should be attempted only by the most experienced visuai observers, or those with photoelectric photometers. (I am delighted to say that Andy Hollis is contributing PEP work on some of these difficult eclipsing binaries.) Members interested in the EBP should write to me for further details and for current predictions. In a future Circular I hope to say something about progress on developing computer methods for reducing observations which are superior to the tracing-paper method previously used, on the literature search for improved elements for eclipsing binaries and newly discovered systems, and on the reports to be published in the Journal listing and discussing members' eclipse timings. 3 John Isles

6 L -ts T A OX Aqp I S t C OX i o r 71 fe>. b V <.? '? ( 17 V805 A c l 7. S - S-9 e a < ,, λ A u p I 5-.T - (c. M- A G Aup Τ Ι f o o J? 30 ( ')T 6 - a 9 S ur 7 fe.t - fc>. 9 A» « s < Aijp 7( fo CO t u p r «o EA ? X 0 A i. r -7.a 8.5 A u..' « / 7 hpo 7-7. a a f x _ (. ' ) 744 ZZ Poo IX ' C!-.a 5.-7 _ fc.3 A i HZ Cas G.x A '0? 5.3 i)? 5 i TV Cas S -X A Cas f c. l A Cep fc-8 - ~ < b l A p o VO Cep I X E W έ o.? ,)2 7 ' ) V3 C e r I I ίϊ C Ceo 7 ~ r.b 9 o e a o ? Ο.'0256 o , C C" Cen σ 23 C o? O.l j.07.,) c l Ceo S.x EA ) C I C e r O.P H, G«C er 7 fep.q EB ? X 6? 4. 7()63 J GK C e r I I 7.M II C r Ψ EA } i Y Cvo ? A ',1 ij o 0 Y Cyp I I O o I) " ( - fc.m- A 1 V1143 Cyo V1425 Cyo X S M- B o i> V1425 Cyo U ^.2.

7 *0* T K Ora -7. a - a. i e a , AT Ora * I E A ? H Ora fc.o S.E EA 10 i '? o.i'.i 401) συ β.o - Io. l EA ? u Her *+ < > E.3 E B () Me r -7.¾ - 1 B-l EA r R* h e. T a e a ? 34 Γ. Ι RY H er Π "7.S V 34 P AP 1 ac I f e. t - f e. 9 E A 22 1) II AP Lac I I fe.m f A ' Leo T S.o EVs/ Ο I a " Leo IJ in ifiA ft U Oph s -a - fo.fe e a :; A4I ι; ,7?.3 i) U 1' pph I I fe-s (-.. I / 0, i } (.., 056 ' V451 P rh -7.a e a <) o m?.xqp ' t>h I I , * V 5 ftft O p h T -7.«S.O EW 17 5 l*. U 04» 59 <> V566 Oph J I -J a ()/, u. a V1010 Oph T 0 1 Ί.Ο t & /101" Oph T I fe.e r.; ) ? EE Peo f e. a - y. f e e a f> Ο ()8 D M A p r e. σ e a P e r J ¾ EA x Π P e r i 7-9 q. o e a η 3.--) P e r IX " B e ta o p r a. ι - 3.M- EA /, Psc EA ? 2a 0. 1, Sae fe.fe A. i EA u )7 / 4. 4 ό.λh 3. 5RU626 V5l>5? q r fe EA (,. 25 8, c co Tau a e a

8 ? 05 I.0 6? ? j 1 > 7 CO Tau XI ν. η ( r-5 6.0,¾ _? uh Tau s. a - fe - 7 e A ^,6 i- ).) )2 09 W U -'a T -7 a - S C, EIa/ 4 0.? 56 1 <i < Τ' U *a X. 1 S. S I 0 i/,.5 4 /, T* 0!.θ. -7 I S E A 10 4? ,, V ul Ί * * a 2. A ?o n. n < [We w o u ld a p o lo g iz e t o m em bers f o r t h i s a p p a r e n t w a s ta g e o f s p a c e, b u t as th e y w i l l a p p r e c ia t e th e s e L i s t s h a v e h a d t o be r e p r o d u c e d fr o m h a n d - a n n o ta te d c o m p u te r p r i n t - o u t, b o th t o a v o id th e t a s k o f r e - t y p i n g a l l th e m a t e r i a l, and a ls o t o p r e v e n t e r r o r s i n t h a t t r a n s s c r i p t i o n. ]

9 L I S T & RT And - IO. 12- EA TW And s. s - ιο.η ea BX And 8 -. fc EW RY A pr S- S to. 1 EA ST App A - 2. q."7 E& KO Apl «3 - A. 5 EA KP Aol I A. 7 ΙΟ.Μ- EA KP Aol I I IO.lt A pl I < EW Apl I I V342 Apl 9? ΕΛ V346 Aol ^ EA VB43 Anl Efl V889 Apl I S V q. - a e a V889 Apl I I *=ί Ι RX A p i _ SX Au P I S E& SX Au p I I 8.G TT Aup TT Aup I I β BF Aup I ¾ BF Aup I I IU Aup I E B ii ; IU Aup I I (i ; IY Aup IO.I E AO Boo 7 7 ιο.ψ E & SV Cam AS Can I S. 2L - S.<g EA AS Cam I I 8 ( AT Cam I - $ io - L W <2 lo.g EA

10 AT Cam I I io G AW Cam I?. 3 _ «. 7 ee, I Aw Cam I I / J AY Cam a. a - io.~7 e a TU Cnc a a _ I X. 4- A WY Cnc q. f c - - lo.m - a XZ Cnc I a. s ep> XZ Cnc I I RS CVn w. L + _ a a e a VZ CVn I a. x -- a "7 T VZ CVn I I YY CMi I S' a. I EB , YY CMi I I TW Cas 8-¾ - a e a TX Cas I a. x -- a. 8 E B ? TX Cas I I a t, ? ON Cas I. η I o. 3 A ON Cas I I IO Cas S L> - a. 3 E B KR Cas M I I O MN Cas I s. s a 3 E A P MN Cas I I a OX Cas I a e a ? OX Cas I I i o ? V368 Css *?. S a x e a V369 Cas I a. a io. 9- A V369 Cas I I IO , WX Cep I a. i a «e a , WX Cep I I XX Cep a I - I O. 3 A , ZZ Cep S.G a. G e a CO Cep I <8 -G a. I E B

11 CQ Cep I I o EG Cep I 9 3 Io. 2_ A EG Cep I I EK Cep «.X - a. S GT Cep S. x 3. 8 EA SS Cet < Ί.ι+ I2>.o A T7 Cet I 9. "7 9 I A T7 Cet I I l o WY Cet q. f o ΙΟ. Ψ XY Cet I S.G - 9. ¾ XY Cet I I q. i C r t I IO. < D C r t I I l o. X Sw Cyg 9. x - 11.*9 A BR Cνα 9 4 io. & A DL Cya 9 Ισ X CA GO Cya KR Cvg q. x IO. i EB MR Cyg I 9 7 A MR Cyg I I 9. I MY Cyg Ψ A _ V453 Cyg I 3. ¾ - % 7 EA V453 Cyg I I S O V382 Cyg I S EB , V382 Cyg I I V388 Cyg 1 "7 - IO. 3 B * V477 Cyg s. s - 9 ¾ EA V478 Cyg 1 S d - 9.¾ E A Cyg I I V548 Cyg s Cyg I q 7 io. / EB

12 V828 Cvg IT Io. I V836 Cvg S. G a x E E V885 Cyg I a a ΐσ 3> B V885 Cyg I I Io V891 Cyg a. 3 - a. a V909 Cyg a. 3 - a ί V1034 Cyg I a t, - io. g es> V1034 Cyg I I a.a V1061 Cyg a 3 - a. a e a A Del a ¾ a TY Del a. -? i o. a SX D ra a s - II. G A TZ D ra a t - l o. S UZ D ra I a. a - - I o. -? E A LIZ Dra I I lo. G , AA Dra I S.3 q. S A A A D ra I I s a BS D ra I a. s - io.3 > a BS Dra I I Io RU E r i a. a - to.7 B TZ E r i a s IX.C A «o. i AX E r i a.s - Io.? > tp, ' YY E r i I s. s a s evo ' YY E r i I I a w ' AS E r i S 3 - a. o e a BZ E r i a - I O t f l Ό CW E r i I S.G Efl Cw E r i IT S - Ψ R W Gem a - G - n. s e a A a Gem I a a t o. s e b AW Gem 11 IO YY Gem I a. 3 - a s a ( uv)

13 , ( YY Gem I I «ι. ί AL Gem 9. 3 IO. M- EA TT H er 9 t io. 3 EB> TX H er I 3.S _ ^. 3 ca TX H er I I < UX H er l. I IO. 7. E A AK H er I 8. a EVy AK H er I I DI H er I A DI Her I I - δ η 1« HS Her 3.S - 9 o A MM Her t A RX Hya 9 - fc 11. Ο EA , VZ Hya β o 9-7 E A P , )1 CM Lee I * cl e r\ CM Lae 44 I I «.S UV Leo I ι-ζ IO.O. t A IJV Leo I I IO. I UZ Leo I a. s i o. I w , UZ Leo I I AP Leo I 9-7 io.3 > EUZ AP Leo I I ES L ib 7. i 7. f o F B I SH Lvn 9 s ( o. x E A UV Lyn I evv UV Lyn I I TT L y r 92» - II. U- F A TZ L y r 9 M - - io. Ψ ΕΈ> UZ L y r 9-3 u. ο FA PL L y r ¾ FA Rw Mo n 9.¾ 11.1¼ F A

14 UY Mon I A 1σ to. I E B UY Mon I I lo.o Mon I a.b A. A EA Ό , A0 Mon I I A « ' BB Mon A. A - to.m- ER H I Mon I IO- 3 E B H I Mon I I t o. x V44B Mon I A - 4 A -A t B , V448 Mon I I I S RV Oph A.4 - EA WZ Oph I A - l a s e a wz Oph I I a / V5O2 Ooh I S.3 - e w V502 Ooh I I 8% V839 Ooh I A.U io. O E.VJ V839 Oph I I to.o ER O ri I A - 3 lo. o e w ER O ri I I t o. o FO O ri A -G - io. Ψ ea , FT 0r< I A l A - A EA FT 0r1 I I A G U Peg I A. x A «t w U Peg I I A AT Peg A S - t o - 3 EA BK Peg A-A 10.7» EA DI Peg A S to.q> EA DK Peg A A _ IO.V EA GH Peg I =1.¾ E A GH Peg I I a.x Z P e r A V Ι Χ. ψ EA RY P e r A ST P e r A V - I. G EA

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19 NEW MEMBERS: S. L u b b o c k - 9 Meadow C o u r t, S t B r id e s M a jo r, B r id g e n d, M id -G la m o rg a n A. M i l l e r - 48 S c a f e l l D r iv e, P e m b e rto n, W ig a n, L a n c s. WN5 9TX G. Ram say - 11 L a d y w e ll G a rd e n s, E d in b u r g h EH12 7LQ R. R u m ble - 30 V ic a r s W a lk, G o ld in g r o n, B e d fo r d, B e d s. MK41 9HG

20 VARIABLE STAR SECTION CIRCULAR 55 CONTENTS E d i t o r i a l 1 S u b s c r ip t i o n s - a c o r r e c t i o n 1 V e r a n d e r ic h e S te r n e ( V a r i a b le S t a r s ) b y C. H o f f m e is t e r 1 E p s ilo n A u r ig a e 1 O r b i t a l p e r io d s f o r some c a t a c ly s m ic b i n a r i e s 1 E c l i p s i n g B in a r y P ro g ra m m e : I n t r o d u c t i o n 2 L i s t A 4 L i s t B 7 L i s t C 13 L i s t D 16 S e c t io n O f f i c e r s C i r c u l a r S C h a r t C h a rg e s in s i d e f r o n t c o v t C h a n g e s o f A d d re s s a n d New M em bers in s i d e b a c k c o v e i * * * * * * 0 * * * * * *