# 4e partie # # 1er partie : Le transit de Vénus devant le Soleil le matin du 8 juin 2004 # 2e partie : Des images # 3e partie : " Les observations de l'effet de la goutte noire. " # 4e partie : Des animations / l' explication du phénomène goutte noire / Un questionnaire # 5e partie : Une explication proposé (la goutte noire) /Une animation # 6e partie :Notre section qui traite des images du satellite TRACE (Transition Region and Coronal Explorer) # Part 6 : Images from satellite TRACE (Transition Region and Coronal Explorer) Anglais # 7e partie A (1 de 2) : Nous avons tenté de reproduire par logiciel la goutte noire !!! # 7e partie B ...(2 de 2) : Les effets détectables de la goutte noire (Isophotes et ...) # 8e partie : Détermination de la fréquence de coupure et de la fonction de transfert de modulation, et du Point spread function (PSF), des télescopes mentionnés dans ce document. # JSRAC colors " The transit of Venus against the Sun on June 8, 2004 " by MICHEL DUVAL, ANDRE GENDRON, GILBERT ST-ONGE AND GILLES GUIGNIER Amateur Astronomy Clubs of Dorval (CDADFS) and Montreal (SAM), RASC # JSRAC couleurs Le transit de Vénus devant le Soleil le matin du 8 juin 2004 par MICHEL DUVAL, ANDRE GENDRON, GILBERT ST-ONGE et GILLES GUIGNIER du club d'astronomie de Dorval CDADFS, et de la SAM (RASC).

# 4e partie #

Par des membres du CDADFS Principalement G. St-Onge P. Scattolin et L. Morin - Montage, méthodologie et développements de cette section : G. St-Onge - Les images sont de : A. Gendron et G. Guignier - Vérification des textes : L. Morin

- Une animation de l'effet de la goutte noire (images de André Gendron) - Deux animations de l'effet de la goutte noire (images à haute résolution de Gilles Guignier) - L' explication du phénomène tel que proposé par Couderc et Danjon en 1969. - Un questionnaire qui rejoint des personnes de plusieurs endroits dans le monde. (avez-vous vu la goutte noire)?

Une animation de l'effet de la goutte noire (images de André Gendron)

Résumé L'animation (Images de André Gendron) Au Celestron de 11 pouces (C11), en photo conventionnelle au foyer F/10. Le phénomène est très détaillé dans le temps : Les premières images montrent un affaissement sombre du bord du disque solaire tout près de la planète Vénus. Puis l'affaissement s'assombrit en s'étirant jusqu'à toucher le disque de la planète Vénus. Enfin un pont sombre et large de la teinte du disque de Vénus l'unit au bord du disque solaire.

Animation de Gilles Guignier ====================

Résumé L'animation (Images de Gilles Guignier) Sur l'animation des images de Gilles Guignier, on constate que l'effet de la goutte noire est très mince et pâle. La haute résolution de ces images atténue la densité de la goutte noire. Ces images sont d'une qualité exceptionelle.

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Patrice Scattolin nous présente : L' explication du phénomène tel que proposé par Couderc et Danjon en 1969. L' explication de phénomène tel que proposé par Couderc et Danjon en 1969. Malheureusement il n'y a aucun article par les deux en 1969 dans l'ADS. J'ai cette citation sur le groupe Maksope et il faudrait demander à l'auteur une reference plus précise -------------------------------- The phenomenon known as the black drop, which affected observations of the interior contacts of Venus' transits can also be seen in the case of Mercury's transits. It is due to diffraction and can be reproduced and photographed in the laboratory. "When the planet encroaches the disk of the Sun, diffraction smears two brilliant points which close again behind it, and which actually are quite distorted. When they are about to meet, Mercury seems attached to the solar limb by a kind of stalk, like a drop which is separating from a narrow opening... To observe this phenomenon, it is necessary to employ a magnification much higher than the optimum magnification calculated for the free aperture of the refractor. For example, for an aperture of ten centimetres, a magnification of at least 150 times is needed. Like the alleged volcano on Mercury, the black drop can be easily reproduced in the laboratory and can be photographed." (A. Coudercand A.Danjon, 1969).

================================== Un questionnaire qui rejoint des personnes de plusieurs endroits dans le monde. (avez-vous vu la goutte noire)? Patrice Scattolin de la SAM (Société d'astronomie de Montréal) et du centre francophone de la SRAC (Société Royale d'Astronomie du Canada), nous a fait parvenir ce mot. Il a contacté des observateurs à travers le réseau de la SRAC (au Canada et ailleurs), en leur posant la question suivante : Avez-vous vu la goutte noire ou pas ? Voici les réponses qu'il a eues. ------------------------------------ Patrice Scattolin a écrit : Hi folks, There's an argument breweing about the black drop effect. Does it exist or not? The "rich" quebec astronomers who went to France to observer it all report not seeing it and they therefore claim that the effect does not exist, whereas some people in montreal observed and recorded the effect. So to try to sort this out I want to do a small survey. Hopefully that will help sort out what effect we are seeing here and at the very least it will document the observations. One question is if seeing or location plays a role (sun at zenith in france vs sun on horizon in Canada). So, if you could you answer the short survey below (don't answer the questions you can't) 1 - Did you see the black drop (yes/no) 2 - where (location) 3 - seeing 4 - transparency (a guess really since it's hard to gague) 5 - local conditions (any info related to weather welcome or location welcome such as a cliff overlooking a great lake) 6 - instrument used (focal lenght, eyepiece lenght, type) 7 - do you have photographic image 8 - Anything other info welcome. =========================================================== Les réponses : Michel Duval CDADFS 1 - Did you see the black drop (yes/no) - oui 2 - where (location) Parc Surrey Dorval Qc. Canada 3 - seeing - ~3 à ~4/10 4 - transparency (a guess really since it's hard to gague) - de ~2/10 à ~ 6/10 5 - local conditions (any info related to weather welcome or location welcome such as a cliff overlooking a great lake) - Près de l'aréoport de Dorval. + Très humide + Très instable ... 6 - instrument used (focal lenght, eyepiece lenght, type) - Maksutov Orion de 127mm, f/12 7 - do you have photographic image - Non 8 - Anything other info welcome. =========================================================== Denis Bergeron Qébec Canada > Sondage > > 1 - Did you see the black drop (yes/no) > Oui > 2 - where (location) Station satellite de Cantley > 3 - seeing Très mauvais, beaucoup de turbulence > 4 - transparency (a guess really since it's hard to gague) On a observé le transit de Vénus à travers un voile de cirrus > 5 - local conditions (any info related to weather welcome or location Cirrus > 6 - instrument used (focal lenght, eyepiece lenght, type) Meade 20cm F10 Lx-200 avec webcam Toucam pro et caméra vidéo Sony branchée en piggyback sur un télescope Bushnell Spacemaster. > 7 - do you have photographic image Oui, allez voir le site web du RAAOQ (adresse ci - bas) dans la section TRANSIT de Vénus > > 8 - Anything other info welcome. > Vous trouverez le compte-rendu de nos observations et nos images sur notre site web du RAAOQ. http://www.astrosurf.com/outaouais =========================================================== From: Dave McCarter #1 - Did you see the black drop (yes/no) - Barely, not at ingress and only slightly at exgress. Photos taken of the event at 1/1000 sec seem to show that the diming between Venus and Sun surface must be a result of local seeing and the extinction due to high Venus atmosphere, above the cloud tops. #2 - where (location) - Mirthios, Crete (on the southern shore, just north of Plakias) #3 - seeing - Lousy, 1 of 5, at beginning due to strong winds, improving considerably to 3 during the later half of the transit. #4 - transparency (a guess really since it's hard to gague) - Totally clear, wonderful blue sky. #5 - local conditions (any info related to weather welcome or location - Located on south side of 1500m mountain ridge. Cloud seen over ridge to the north but none overhead. North winds peaking to 70km/h, sustained at 25km/h during most of the transit. Telescope set up in a sheltered position behind buildings, where daytime roof heating most probably contributed to poor seeing, but the better of two evils, as telescope shake was extreme out in the wind. #6 - instrument used (focal lenght, eyepiece lenght, type) - 90mm ETX with Badder film filter, 32mm Plossel and 13.8mm SWA eyepieces. #7 - do you have photographic image - Yes, 159 digital images of transit. Some show possible black drop effect, which on close inspection show seeing and Venus atmosphere artifacts. I'll post some on the London Centre web page tomorrow, after tonight's meeting. Dave ============================================================ From: Steve Barnes #1 - Did you see the black drop - - YES - definately #2 - where (location) - West end of Lake Ontario (Beach Strip in Hamilton) #3 - seeing - variable - average-poor #¸4 - transparency - a guess really since it's hard to gague #5 - local conditions - set up just off the beach overlooking the Lake Ontario #6 - instrument used - Three instruments used A ) TeleVue 101mm refractor with 40mm Coranado H-alpha filter used photographicly at prime focus with Philips Toucam Pro B ) Meade ETX90 - used with MiniDV camcorder (White Light with Thousand Oaks photo filter) and Teleue 14mm Radian afocal C ) Meade 4" Schmidt Cassegrain used visually with Badder filter #7 - do you have photographic image - YES. I can supply these on request. Email me at Thanks, Steve Barnes ============================================================== From: Dan Taylor #1 - Did you see the black drop (yes/no) - Yes #2 - where (location) - Central Essex Co. On., 42°11' N 82°47' W #3 - seeing - 3- scale1/5, 5 best #4 - transparency (a guess really since it's hard to gague) - Poor, substanial haze. #5 - local conditions - Open farm land #6 - instrument used - 4" f 10 Mak, Tuthill type filter.- negative obs. - 4" f 16 refractor, projection method- Positive obs. #7 - do you have photographic image? - Images indicate levels of greying in the area between Venus and the solar limb. Prescise moments of "black drop' was missed > Dan Taylor ============================================================== From: Aimee & Dave Pianosi #1 - Did you see the black drop (yes/no) - Nothing convincing #2 - where (location) - just North of Kingston ON #3 - seeing - Poor seeing with some haze #4 - transparency (a guess really since it's hard to gague) -6/10 #5 - local conditions -looking over Sydenham Lake #6 - instrument used -10" Newtonian with 5" off axis Baader #7 - do you have photographic image - no Dave Pianosi KIngston and Belleville Centres ============================================================ From: Ralph Chou Hi, Patrice. #1 - Did you see the black drop (yes/no) - Yes - very slight effect visually at ingress, not seen at egress; possibly recorded on one or two frames on film #2 - where (location) - Hurghada, Egypt #3 - seeing - Poor - lots of convection, light wind, 40C #4 - transparency - Light sand haze #5 - local conditions - 4 m above sea level, next to Red Sea and hotel swimming pool #6 - instrument used - TV Oracle 3-inch - f.l. 560 mm with 3X telextender on SLR camera back #7 - do you have photographic image - Yes Ralph Chou Toronto Centre ======================================================== From: Harold Tutt #1 - Did you see the black drop (yes/no) - Ingress No (transit approx 3/4 complete Egress Yes #2 - where (location) - Open farmers field approximately 10 km southeast of London, Ontario #3 - seeing - Morning fog and haze for 1st 5 minutes (allowed us the view with naked eye) seeing improved to clear skies and 7 out of 10 #4 - transparency - N/A #5 - local conditions - Farmers field clear view of horizon for Approx 3km in the from NNE to SSE #6 - instrument used (focal lenght, eyepiece lenght, type) - Meade 10 " Dobsonian, 17mm Vixen Lanthanum eyepiece, Badder filter with homemade cell Stellerview 80 mm AT101N, 13mm & 2x barlow, mixing eyepieces of 13, 17, 22 vixen Lanthanum & 30 mm teleview #7 - do you have photographic image - N/A #8 - Anythiing other info welcome. - N/A Harold Tutt London Centre ========================================================= From: Mark Viol #1 - Did you see the black drop (yes/no) - Not visually, however it did show up on one of my shots with an 80mm refractor + 11 megapixel camera. #2 - where (location) - Toronto Lakeshore. #3 - seeing - Very turbulent at sunrise; modest improvement by the time of 3rd contact. #4 - transparency (a guess really since it's hard to gague) - Very hazy. #5 - local conditions - Very humid, looking over the downtown core. #6 - instrument used - Orion ED 80mm + 14mm Pentax (Canon 1Ds) #7 - do you have photographic image - Yes. #8 - Anythiing other info welcome. - With the turbulent seeing, it would have been most difficult to see the black drop effect from our location. I believe it was pure chance that I fired the shutter at a moment of steadier seeing. ====================================================== From: Raymond Auclair #1 - - Did you see the black drop (yes/no) - Helene yes At or around second contact (how would I know, I did not see anything) we clearly hear Helene say (in French) ''well, the sun's limb is now complete and the black drop has disappeared. Venus is completely inside. I guess that part of it is over''. #2 - where (location) - We were in Gruyeres, Switzerland, the village that gives its name to the cheese made there (I guess I did not want to be with the poor people, visiting France). #5 - local conditions - Gruyeres village, sits atop a ''small'' 800-metre mountain surrounded by 1600 to 2000 m Alps. #6 - instrument used - However, just before leaving Ottawa, I bought a very inexpensive ($80) scope for Helene to give her something to do during the transit. She saw the transit very well AND got to show it to various people... Raymond Auclair ============================================================ From: Meier #1 - - Did you see the black drop (yes/no) - No, did not see it. Mind you, this was on a monitor, not through the eyepiece. But I have gone over the recording very carefully and did not see anything but a bright line between Venus and the sun at any time before 3rd contact. Here is a frame from a moment of good seeing: http://www.cyberus.ca/~ec088060/images/image110.jpg Frames were taken every 3 seconds, so if it lasted less than that time it could have been missed. #2 - where (location) - This was in Ottawa, seeing fair to good, very hazy, 6-inch f/12 refractor, Baader solar film. -Rolf =========================================================== From : Jay #1 - Did you see the black drop (yes/no) - yes #2 - where (location) - Crete (Chania) #3 - seeing - very good #4 - transparency - very good #5 - local conditions - sea breeze conditions contributed to steady seeing. Morning fog was indicative of very stable conditions. #6 - instrument used - Nexstar 5i at 50X and at 125x with Baader solar filter #7 - do you have photographic image - no, I wanted to see the phenomena. #8 - Other: - We were also able to see the atmosphere of Venus extending above the solar limb, and all of the way around the planet when it was more than half way onto the solar limb. This was a much more difficult observation than the black drop. Jay Anderson Winnipeg Centre ========================================================= From : Bill Ronald #1 - Did you see the black drop (yes/no) - Yes, slightly at ingress and very slightly at egress #2 - where (location) - Cyprus (near Paphos) #3 - seeing - Not great ... there were intermittent clouds, particularly during ingress #4 - transparency - There was some sea haze in the morning and high, thin, fast-moving clouds later in the day #5 - local conditions - Set up on a NE-facing balcony of our apartment about 3m above ground - Whole transit was visible from it (another half hour and I would have lost the Sun) - Elevation according to GPS was 11.75m - There was a continuous wind blowing from the N and W, which frequently shook the telescope #6 - instrument used - Telescope: 80mm ED f/7.5 refractor the filter used was an Orion glass solar filter which doesn't give as sharp an image. - Mount: Manfrotto #190SH tripod with a #410 geared head - ... manually guided ... aching back!!! During ingress and egress: - Supercircuits PC-23C surveillance camera (hacked to reduce blooming) - Black Box Camera Precision Time Inserter with a Garmin GPS16 sensor - Recorded into a Sony Hi-8 videocam During most of transit: - Nikon FM2 camera with 3x teleconverter - mounted on the above telescope and mount to give an 1800mm f/22.5 lens - Fuji Provia 100F slide film #7 - do you have photographic image - Yes, captured from the video, but due to conditions (weather, vibrations, etc.) they are not great without being digitally cleaned up #8 - Anything other info welcome. - Wish I had been able to take a tracking mount! - This was the only day that we saw any clouds at Paphos during our week's stay!! Bill Ronald, Vancouver, B.C. ====================================================== From : Paul Campbell #1 - Did you see the black drop (yes/no) -Yes, very slightly at egress (3rd contact) Major blackdrop effect on rising (Venus with horizon) though I'm sure that was a refractive event. #2 - where (location) -Near Syncrude, Fot McMurray , Alberta #3 - seeing -Extemely awful. The Sun was about 2 degree up at third contact. Lots of spikes and indentations on the Sun at sunrise. (Way Cool!). The general shape of the sun was a oblate spheroid (football). Green on the top of the sun, red on the bottom. Venus showed red on the top of the sun and green on the bottom. #4 - transparency (a guess really since it's hard to gague) - Pretty good. Some fog below us. #5 - local conditions - Observed from a smooth rising bluff looking over a large expanse of tailings from Sycrude. Slight fog below us, heavy fog further down in the valley #6 - instrument used (focal lenght, eyepiece lenght, type) -12.5" newtonian, f/4.9, 20mm nagler eyepiece #7 - do you have photographic image - Yes =========================================================== From : Geoff Gaherty #1 - Did you see the black drop (yes/no) - No. #2 - where (location) - Cathedral Bluff, Scarborough, ON #3 - seeing -Poor: 2-3 on a scale of 0 to 10. #4 - transparency (a guess really since it's hard to gague) - Very good, 4 on a scale of 0 to 5 #5 - local conditions - On cliff overlooking Lake Ontario, but Sun was quite high by third contact (13° altitude). #6 - instrument used (focal lenght, eyepiece lenght, type) - Orion 127mm f/12.1 Maksutov-Cassegrain, 1540mm f.l., with Meade8.8mm Ultra Wide eyepiece (175x). #7 - do you have photographic image - No. #8 - Anything other info welcome. - Although I didn't see any sign of a black drop effect, I did see the partial extension of Venus' atmosphere off the solar disk for a couple of minutes after third contact. Geoff Gaherty Toronto Centre RASC ==========================================================