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« Jas de Tardivy »
Observatory in Caussols
Brief History and Some Deep-Sky Images
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Patrice Poyet, Jean-Pierre Vida and Joseph Abad
Observatoire du Jas de Tardivy à Caussols
Mosser (43.748825 – 6.939806) and Cardoen (43.747978 – 6.936663) telescopes
Postal : 5, avenue Corniche d'Azur, 06100 Nice, France
patricepoyet@yahoo.com
Introduction
The « Jas de Tardivy » Observatory is a small private facility located half a mile east of the CERGA (Centre
d’Etudes et de Recherches en Géodynamique et en Astrométrie) which is now part of the larger French
national research unit OCA headed by Farrokh Vakili since 2009: https://www.oca.eu/spip.php?rubrique406
In the early seventies, an observation site was established on the Calern mountain for undertaking
astrometric measurements (Levy, 1971), (Kovalevsky, 1972) and the largest European Schmidt telescope at
the time was installed there (152cm spherical mirror, focal length 3161mm and 90cm Schmidt corrector) and
I was lucky to meet Jean-Louis Heudier
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acting as a tireless promoter of the site and more generally of
astronomy to a large public, always available for a drink and for a nice discussion at the “Auberge de
Caussols” with René Gili, Jacqueline Ciffréo
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, François Rouvière and his solar telescope and other friends.
Therefore, when in the late eighties I envisaged establishing a private observatory, it was no surprise that I
tried to find a place not far from the CERGA (Rozelot, 1985), (Granes, 1988) to install my telescopes as I
had built several following the methods described by Jean Texereau and (Danjon et al., 1979). As presented
in (Kovalevsky, 1975) there are on average 170 absolutely clear nights in Caussols with an additional 70
nights allowing a minimum of 2 consecutive hours of observations. It was acknowledged that a halo from
the urban areas of the Côte d’Azur could be annoying but quite often maritime low level clouds enter the
low land countryside and hide completely from Caussols the lights from the coast. Therefore, I was lucky
enough to buy a 7,8 hectare piece of land late 1989, where we started installing in 1990 the first instrument,
i.e. the Mosser
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telescope. Then in 1995 work resumed to build a larger 25 inches scope that would be better
suited for deep-sky observing. The mirror was originally shaped by Dany Cardoen and when time came to
deposit a new aluminum coat David Vernet improved the optical surface to make it a dream.
Since the project started we have installed two telescopes, one designed for the observation of planets and
double stars under the Mosser Dome (6° 56' 19" E, 43° 44' 58" N, 1185m) and another for deep sky
observing under the Cardoen Dome (6° 56' 16" E, 43° 44' 57" N, 1145m). CCDs observing has been the
major objective since the beginning.
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Published as a white paper in www.researchgate.net/profile/Patrice_Poyet with DOI: 10.13140/2.1.1313.8885
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https://www.researchgate.net/profile/Jean_Louis_Heudier
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Discover of 108P/Ciffreo http://fr.wikipedia.org/wiki/108P/Ciffréo
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Roger Mosser (1936-1990) was born in Strasbourg and as a self-educated optician started with a 310mm Cassegrain telescope
for his Valff observatory in 1969, then a 510mm Cassegrain in 1975. He has produced more than 450 mirrors in 16 years of all
types, including Newton, Cassegrain, Wright, Ritchey-Chrétien, Schmidt, flat blades, flat mirrors, etc., most to better than
lambda/30.
Beyond the telescopes themselves, the design and erection of the domes hosting the telescopes was also the
result of the work of a limited team of three people. Beyond myself, Joseph Abad worked on all parts of the
project, including the 5 meters dome of the 16 inch Cassegrain (originally twin telescopes), the 5 meters
dome of the 25 inch Newtonian and the refurbishing of a small house, the use of which is invaluable for the
observers who deserve rest, heat and coffee after the cold nights spent on the Calern mountain of the French
Riviera (1200 meters above the sea level). Jean-Pierre Vida was the manufacturer of the 5 meters dome of
the 16 inch Cassegrain which was disassembled and transferred from Nice (where he built it first) to
Caussols and also gave a major help for the steelwork of the 5 meters dome of the 25 inch Newtonian. Jean-
Pierre provided a very significant help at critical moments and nothing would have been possible if he had
not been there during these phases.
Mosser Telescope
The Mosser telescope is a 16 inch Cassegrain (400 mm) at F/D=5/27, closed by a special borosilicate crown
flat designed to minimize the thermal exchanges between the telescope and the environment and is hosted by
a 5 meters dome. The telescope is named after Roger Mosser the French amateur astronomer and optician
who ground the optical combination and sadly died in his fifties. This telescope has been operated since
1990 and has delivered a number of excellent images of the moon and the planets. Supported by a German
mount, the Cassegrain telescope has also been piggy-backed by a 16 inch Newtonian during the years 90-95,
waiting for the Messier 25 inch Newtonian to start operating. Fall 95, when the 25 inch Newtonian has
started operating the 16 inch piggy-backed Newtonian has stopped being used. It was later removed during
the summer of 1996. The first camera used was the ST6 with the small TC241 chip (375x242 pixels - 23x27
microns cells) and the typical focal length used with these telescopes are:
the primary Cassegrain focus of 425 inches (10,79 meters) mainly used to image some bright
planetary nebulae and the moon ;
an extended Cassegrain focus of 923 inches (23,44 meters) mainly used to image the planets ;
the primary Newtonian focus of 78,74 inches (2,00 meters) mainly used to image deep sky objects ;
an extended Newtonian focus of 173,50 inches (4,40 meters) mainly used to image details of deep
sky objects ;
The dome appears after having been covered with metal sheets to better protect it from weathering. My
young daughter Coralie (kind of 2 years old at that time in 1993) gives somehow the scale.
An overall view of the telescope and its German mount from inside the opened dome.
This is a front view of the optical system of the Cassegrain telescope showing the borosilicate crown
isolating the tube from the external environment. The small secondary hyperbolic is directly supported by
the flat.
Cardoen Telescope
The Cardoen
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telescope is a 25 inch Newtonian (620 mm) supported by a large cradle and hosted by a 5
meters dome. Once a year, an entire night is allocated for the Messier Marathon to log all the Messier
objects in a single night.
The telescope started operating early December 1995 and is devoted to deep sky observing, including the
monitoring of comets, asteroids and SNe. With the first ST6 and the small TC241 chip (23x27 microns),
considering the focal length at the primary Newtonian focus of 106,57 inch (2,707 meters), it gives a scale
of 1,7432" arc second in X cross 2,046" arc second per pixel in Y mainly used to image deep sky objects.
The field covered in that configuration is 10',89 arc minutes in X cross 8',25 arc minutes in Y.
Many other cameras have been used since including the ST2KXCM+AO8 (adaptive optics) which delivered
excellent color deep sky images and the ST10. Many projects are run with this telescope and most of the
deep sky images and all the images of comets have been made with this instrument.
Various images of the construction of the telescope and of the dome are available hereafter:
The steelwork structure just finished with Jean-Pierre Vida.
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Dany Cardoen is a Belgium Flemish amateur astronomer and optic and telescope designer and builder
http://nl.wikipedia.org/wiki/Dany_Cardoen who installed various facilities in Puimichel (Alpes de Haute-Provence, France)
including a 1,06 meter Cassegrain http://puimichel.obs.free.fr/
The steelwork and the masonry work with the author standing in front of the future building. At that stage
you need to believe that you will succeed observing galaxies!
The structure of the dome, the steelwork was welded and appears on the blue background of the sky.
Now, I know that I will see the galaxies I had dreamt of as a young man in the Hubble Atlas of Galaxies,
well better say I’ll download their color images on the computer from the CCD attached to the scope!
This is a front view of the optical tube of the T620 Newtonian, my face being reflected in the 25 inches
mirror 3 meters away from the camera.
In 2007 I started refurbishing and reconstructing the building that hosted the 25 inches scope. This is a
picture showing the East side of the building and the Schmidt telescope of the CERGA is visible West on
top the Calern Mountain as a small white blob atop the shovel.
The building hosting the 25 inches scope (West side) and the house refurbished is visible in the background
on top, to host observers deserving coffee and some rest.
The astronomical site of the Observatory
The landscape can be gorgeous. Here at dawn over the cloud deck often standing south of the astronomical
site and extending down on the French Riviera, covering light pollution from the cities.
Côte d’Azur, as seen from the Mosser telescope with the Mediterranean Sea, Cap d’Antibes is located quite
in the center of the picture and that day, but slightly visible, Corsica extending as a very large island and
covering more than one third of the visible horizon.
Short References
Danjon André, Couderc André, 1935. Lunettes et Télescopes, édition de la revue d'optique théorique &
instrumentale, Paris, 715pp.
Danjon André, Couderc André, 1979. Lunettes et Télescopes. Théorie, conditions d'emploi, description,
réglage. Paris: Blanchard, 1979, Nouvelle tirage. 01/1979.
Granes, P. 1988. Observatoire de la Côte d'Azur: C.E.R.G.A. - Le Centre d'Études et de Recherches
Géodynamiques et Astronomiques, Eur. Astron., Vol. 2, No. 3, p. 178 - 183. 01/1988.
Kovalevsky, J., 1972. Projet d'un centre d'études et de recherches géodynamiques et astronomiques en
France (CERGA) Ciel et terre 01/1972; 88:196.
Kovalevsky, J., 1975. Le Centre d'Études et de Recherches Géodynamiques et Astronomiques (CERGA),
L'Astronomie, Vol. 89, p.271-286.
Levy, J., 1971. Le CERGA. (Le centre d'études et de recherches géodynamiques et astronomiques). Bull.
d'Information, Assoc. Dévelopment International Obs. Nice, No. 8, p. 11 - 15. 01/1971.
Rozelot, J.-P., 1985. Le Centre d'Études et de Recherches Géodynamiques et Astronomiques (CERGA) dix
ans après sa création, L'Astronomie. 01/1985;
Texereau, Jean, 1957. La construction du télescope d’amateur.
Texereau, Jean, 1984. How to Make a Telescope (Second English Edition).
http://www.astrosurf.com/texereau/
Annexes – Some images
Jupiter imaged by Patrice Poyet on 930226 with the Mosser Scope, focal length 23,44m, ST6. Total light image exposed 0.35 sec
starting at 01:22:07 UT.
Jupiter imaged by Patrice Poyet on 930314 with the Mosser Scope, focal length 23,44m, ST6. Total light exposed 0.35 sec starting
at 00:56:18 UT. The conspicuous Great Red Spot approaches CM.
NGC 45 imaged by Patrice Poyet on 080830, 25” scope, 60mn exposure ST2KXCM+AO8, CCDOP+CCDSHARP+IRIS+CS
NGC 157 imaged by Patrice Poyet on 080909, 25” scope, 63mn exposure ST2KXCM+AO8, CCDOP+CCDSHARP+IRIS+CS
NGC 772 imaged by Patrice Poyet on 080830-31, 25” scope, 60mn exposure ST2KXCM+AO8, CCDOP+CCDSHARP+IRIS+CS
NGC 6674 imaged by Patrice Poyet on 080827.916, 60mn exposure ST2KXCM+AO8, CCDOP+CCDSHARP+IRIS+CS
NGC 6814 imaged by Patrice Poyet on 080830, 25” scope, 90mn exposure ST2KXCM+AO8, CCDOP+CCDSHARP+IRIS+CS
NGC 6822 imaged by Patrice Poyet on 080825, 25” scope, Mosaic of two images (30mn N and 37mn S exposure)
ST2KXCM+AO8, CCDOP+CCDSHARP+IRIS+CS
NGC 6907 imaged by Patrice Poyet on 080804, 25” scope, 75mn exposure ST2KXCM+AO8, CCDOP+CCDSHARP+IRIS+CS
NGC 6946 imaged by Patrice Poyet on 080803 & 080807, 25” scope, 150mn exposure ST2KXCM+AO8,
CCDOP+CCDSHARP+IRIS+CS
NGC 7184 imaged by Patrice Poyet on 080825 & 080901, 25” scope, 152mn exposure ST2KXCM+AO8,
CCDOP+CCDSHARP+IRIS+CS
NGC 7217 imaged by Patrice Poyet on 080826, 25” scope, 84mn exposure ST2KXCM+AO8, CCDOP+CCDSHARP+IRIS+CS
NGC 7252 (ARP 226) imaged by Patrice Poyet on 080804, 25” scope, 65mn exposure ST2KXCM+AO8,
CCDOP+CCDSHARP+IRIS+CS
NGC 7320 (ARP 319) imaged by Patrice Poyet on 080803, 25” scope, 104mn exposure ST2KXCM+AO8,
CCDOP+CCDSHARP+IRIS+CS
NGC 7331 imaged by Patrice Poyet on 080729, 25” scope, 24mn exposure ST2KXCM+AO8, CCDOP+CCDSHARP+IRIS+CS
NGC 7479 imaged by Patrice Poyet on 080803, 25” scope, 44mn exposure ST2KXCM+AO8, CCDOP+CCDSHARP+IRIS+CS
NGC 7606 imaged by Patrice Poyet on 080909, 25” scope, 60mn exposure ST2KXCM+AO8, CCDOP+CCDSHARP+IRIS+CS
NGC 6656 (M22) imaged by Patrice Poyet on 080802, 25” scope, 18mn exposure ST2KXCM+AO8,
CCDOP+CCDSHARP+IRIS+CS
NGC 6618 (M17) imaged by Patrice Poyet on 080730, 25” scope, 15mn exposure ST2KXCM+AO8,
CCDOP+CCDSHARP+IRIS+CS
NGC 6611 (M16) imaged by Patrice Poyet on 080730, 25” scope, 30mn exposure ST2KXCM+AO8,
CCDOP+CCDSHARP+IRIS+CS
NGC 6614 (M20) imaged by Patrice Poyet on 080730, 25” scope, 15mn exposure ST2KXCM+AO8,
CCDOP+CCDSHARP+IRIS+CS
