How to measure the minima of the Binary Eclipsing Stars an amateur s experiment

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2 How to measure the minima of the Binary Eclipsing Stars an amateur s experiment Laurent Corp Andromède 4A - AAVSO ANPCEN BAA - GEOS - T60 Saturday, October, 23rd, 2010 Sabadell - Spain

3 Who am I? A variabilist observer for ever Visual observations CCD observations Discovery of the double-star measure principle (though never worked on it) Pro/Am Collaboration AAVSO AFOEV - BRNO observer

4 Méthodes de mesures La séparation des étoiles doubles conduit à des méthodes de travail différentes : Astrométrie Photométrie (Binaires serrées) attention les deux peuvent êtres nécessaires. Catalogues différents : WDS GCVS (General Catalogue Variables Stars) Organismes différents : Commissions «étoiles doubles» Associations de variabilistes

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6 How to measure the minima of the B.E.? The Eclipsing Binary Stars The observation in practice Some results Conclusion Questions?

7 The eclipsing binary stars

8 Eclipsing Binary stars (E.B.) Finding minima (2) and (4)

9 3 types de E.B. EA = Algolides Well-marked main minimum, important secondary or almost undetectable minimum

10 Periodical binary variable stars Eclipse principale magnitude apparente Eclipse secondaire Temps (jours)

11 3 types de E.B. EB = Beta Lyrae Well-marked main minimum, secondary minimum as important as the primary round curve due to the gravitational attraction of stars

12 3 types de E.B. EW = W Ursae Majoris Minimum almost identical to the secondary s round curve due to the gravitational attraction of stars In-contact dwarf stars which period is less than one day

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14 Physical caracteristics

15 The observation in practice

16 How to measure the minima of the B.E. Predictions Observations Results Data sending The choice of the star imposes a technic and not the opposite

17 Predictions Choose your star according to its configuration : Hardware Limit magnitude Seeing Light pollution Time of observation how to start The hour of the phenomenon Filtration Softwares Ressources Web ressources Softwares

18 Which stars to choose? Some advices : Attention to indicated times TU Premises Geocentric Heliocentric Check the predictions

19 Which stars to choose? Researches for primary and secondary minimum Prediction softwares Minima 2.0 de Bob Nelson

20 Which stars to choose?

28 The unnoticed targets 141 étoiles à remesurer car négligées par les amateurs Les étoiles sont très brillantes Bright stars

29 Observation in practice The two types of photometry Measure the magnitude of the variable stars with a CCD camera How to prepare your observations To whom and how to send your observations Some light curves

30 The two types of photometry Differential photometry We measure the flow of the Object with regard to a Reference ( " relative " photometry) It is the practised method by the majority of the amateurs

31 The two types of photometry "Absolute" photometry In various air masses, measure a reference field (with filter!) to have the constant of the magnitude Requires a «smashing» sky of constant quality several nights long

32 The «Time-series» Several nonstop images. Every image must be as perfect as possible not to lose the information

33 Advantage of the CCD Better precision 0.02 mag à mag Weaker stars more accessible thus more numerous Software automation necessary for "time-series", especially in multifilters

34 Equipment for the CCD Telescope, finder, telephoto lens Indispensable equatorial frame (the rotation of the field is unwanted). CCD Camera Monochrome No Antiblooming prefered Check the linearity thermoregulated prefered Choose your filtration Softwares Control of the camera Photometry - astrometry Computerized sky chart Indispensable internet connection for the updating of the programs and for the follow-up of the information

35 Operations with your camera CCD Find the field of the variable. CCD images + astrometry program + software of research Taking the images Several hundreds of «time-series» If your camera is ABG (Anti Blooming Gate): work with only 50 % of its dynamics, ex: for one 16 bits If you have several filters, made a sequency: VRVRVR.. Images of calibration : Bias Darks at the same temperature as the images Flats

36 CAUTION Influence of the images of calibrations

37 The filtration Le futur nouveau standard : SLOAN

38 Header Fits What do you find in it? Date, Time in UT Exposure time (inserted or deductible) Temperatures for the regulated CCD Coordinates of the center of the image in RA and in DEC The used filter + All the usual data: Object Camera image size Instrument Observer..

39 Softwares AIP4WIN CCDSoft ASTROART 4.0 PRISM 6 et 7 MPO Canopus V10 Mira MaximDL 5.12 Free IRIS 5.59 AudeLA Teleauto 4.4 Muniwin IRAF et Sextractor Yours

40 Principle of the measure Differential photometry Reference : One star A "super-star": the flow of several stars is added Advices : Use reference stars of close magnitude and close "color" Choose an indication «B-V» or an almost identical «V-R» Attention: check with a measure on a "test" star that your references are stable in time! In practice

41 Principle of the measure

42 Principle of the measure

43 Principle of the measure Measure of the flow on the image by "counting" the signal in a "window" Circular shape Elliptic shape "Do not transform" the image in case of rectangular pixels

44 Principle of the measure By comparison with stars nearby as for the picture. The choice of the diameters of the circles of measure is very important.

45 The choice of the circles Circles define themselves in the following way (FWHM in pixels): First circle The second circle Last circle 2 * FWHM 3 * FWHM 5 * FWHM

46 Errors in magnitude according to SNR SNR Magnitude SNR must be over 50

47 And then Measures with various filters B, V, R, I Measure of the coefficients of transformation Grading of the filters Use the coefficients of transformation

48 The means of observation : instruments and methods applied to the B.E.

49 My setup Garden Observatory

50 My setup T.O.M.M.I.G.O (ST7 + filtres C-V-R + téléobjectif 135/2.8) Time Of Minima and Maxima Instrument Garden Observatory Un baffle est présent dans ces deux configurations

51 My program of observations Little studied eclipsing binary stars HD (work with David Valls) OO AQL publication conjointe BAA-VSS shared publishing V417 AQL - XY LEO Y LEO AB AND RS VUL. RRLyr (shared work with Jean François Le Borgne Midi Pyrénées Observatory)

52 Observations Have your computer at the right hour Ideal observations (acquisitions of the pictures) 1:30 am before minima 1:30 am after minima 1 up to 3 stars by night according to the season or only one in the night for complete phase Make your images of calibrations

53 Observed star : OO AQL ( EW/DW) Period :

54 Observed star : AB AND ( EW) Two minima measured on the same night primary and secondary (period )

55 Other observed Stars RS VUL ( EA/SD) Period : V388 CYG V548 CYG EA/SD Period : Variation of 0.2m in 3 hrs Ephemerides errors

56 Observed star : RR LYR Dispersions maxi : 0.02 in R Better than 0.01 in V JF Le Borgne (OMP)

57 Epsilon Aurigae

58 Last measures

59 Last measures

60 Last measures

61 Analysis of the results Evaluation of the standard deviation of the measure with Excel (quantify the limits of the measure errors ) Calculation of "Airmass", critic of the results Evaluation of the error (knowledge of the flow or the SNR) Constitution of your own programs

62 Send your measures AAVSO EB Commission BAA (la SAF Anglaise) Variable stars commission Astronomical Institute (Ondrejov) Czech Republic EB Commission

63 To know more about it

64 Litterature (THE Book) Lightcurve Photometry and Analysis by Brian D. Warner (30 euros) Livre bien fait, tout pour savoir acquérir,traiter ses images et les analyser. Comment calculer la taille et la température d une étoile ou la taille d un astéroïde. Brian est l auteur du logiciel «Mpo Canopus»

65 Litterature An Introduction to Astronomical Photometry Using CCDs by W. Romanishin Universitiy of Oklahoma Livre de 175 pages reprenant un cours universitaire de niveau accessible sans trop de mathématiques, agréable à lire. pdf evolstar-bmauclaire.pdf en Français 43 pages tout sur la vie des étoiles Limites et lobes de Roche (SAF collectif)

66 Important links AAVSO American Association of Variable Star Observers site complet (base de données des «light curves», cartes, conseils, groupes de discussion, etc...). A mon avis le meilleur site! Manuel pour l observation visuelle des étoiles variables CCD Observing Manual CVnet Cataclysmic Variable network Site donnant les dernières informations sur les CV, interviews de professionnels, bonne introduction aux CV. Compilation des données fournies au AAVSO. ml CBA Center for Backyard Astrophysics site spécialisé pour les Cataclysmiques, reprend entre autres le programme suggéré pour le mois avenir, groupe de discussion, alert notice par .

67 Important links IBVS - Jean Marc Breard - Etoilesvariables.fr - Exercices de photométrie - php

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70 Thank you for your attention Have you got any question?

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