Astrophotography on the Col du Restefond in the French Alps

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As an astronomer, finding a dark observing site in light-polluted Europe is not easy. Finding a well accessible site with passable horizon visibility and transparency is even more difficult. Then to have good weather conditions is a gamble. The Col du Restefond in the southern part of the French Alps in the Parc national du Mercantour promises to fulfil all these wishes: 2600m altitude, located away from larger cities and urban areas, and blessed by the topography with more clear nights than many other places in the Alps. The rainy summer of 2021 in Europe prompted me to head for the Col du Restefond in early July, as the weather outlook was poor for the rest of the Alps during the new moon phase in July. And indeed, in about 7 days I was able to take advantage of 5 clear nights to observe and photograph the southern Milky Way. Two days with bad weather I used for a short trip to the French Riviera.

For an amateur astronomer from West Germany, this is a long drive. A good 1200km each way had to be covered in one and a half days. A high effort and consumption of resources, which is only worth if the conditions are really right and the weather is good. The Parc national du Mercantour is quite remote and far away from highways, so that the approach over several mountain passes consumes a lot of time. However, one is rewarded with a beautiful ascent to the 2800m high Col du Restefond and Cime de la Bonnette. The high alpine vegetation and the breathtaking mountain scenery make up for the long drive.

The picture below shows my observation location at the Col du Restefond in the French Alps in an old quarry in 2600m altitude. A stone wall protected me against the western winds and the horizon view to West, South and East was very good. In the West is a pronounced brightening of the horizon caused by the nearby city of Barcelonnette. The photo was taken with the Canon EOS R and the Irix Firefly 15 mm@f2.5 and ISO3200.

 

 

Before I continue with the description of the location, here is one of the astrophotos I have take during my stay. This is Messier 8 and 20, the Lagoon and Trifid Nebula in the constellation of Scorpius. This shot was taken with my TMB 115/805 Triplet APO and the large M82 0,75x Riccardi Reducer at 600m f5.25. I used the ASI6200MM Pro full format cooled CMOS camera at -15°C.

More deep sky photos taken at the Col du Restefond can be found in my Deep Sky Image Gallery.


Here is a comparison of the horizon view at night between the Col du Restefond in the French Alps and the Silvretta in the Austrian Alps, taken just a couple of days apart at a similar time of the night. During my stay on both locations the sky quality meter measured 21.7mag sky brightness.

Link to the full-res image of the Horizon Panorama

At the Col du Restefond there is an old quarry in an altitude of 2600m on the northern side of the mountain with very good visibility of the horizon towards the South, West and East. Except the light dome of the city of Barcelonette, there is any disturbing light pollution. However, you can see the light glow of the the 150km distant cities of the French Rivera close to the southern horizon, but this is only visible just through the good horizon view. A stone wall helps to protect against winds coming from the West. There are other potential observation areas on some meadows further down the road, but with much worse view to the horizon. Further up the road close to the Cime de la Bonette there are some small parking areas close to the road in an altitude of 2800m with ever better view to the southern horizon. However there is no wind protection and spending the night there could be quite uncomfortable. I have to point out, that there is almost any infrastructure up there. No rest rooms at all, no water, no food, no electricity and limited mobile network access. This is wilderness!

The Silvretta observation spot is on a large long-term parking area close to the Bieler Höhe and the reservoir in an altitude of 2000m. After my stay in the French Alps I made a stopover at the Silvretta High Alpine Road on my way back home. High mountains are surrounding this area. You have a very limited view to the north and a mountains to the south limit the view as well. I have marked Messier 8 as a reference to indicate, how good the visibility of the souther horizon is at the observation spot at the Col de Restefond. Many mobile homes are usually parking on this area during the night; disturbing light can not be excluded. Furthermore, the construction site at the Vermunt Werk at the reservoir has some very bright annoying lights at night, but if you are standing close to the northern boundary of the parking area, this will not be an issue for photographic and visual work. Two hotels are very close to the parking area and provide accommodation, food and rest-rooms. The observation spot at the Col du Restefond is definitely better. However, depending on where you are traveling from, the Silvretta region might be much easier to reach and has much better infrastructure.

 

 

All sky Panorama of the Milkyway at the Col du Restefond, taken with a Canon EOS R and the Irix Firefly 15mm @ f2.5 and ISO3200. The horizon line formed by of the surrounding mountains at my observing location in an old quarry at an altitude of 2600m is quite low and you have a much better horizon view to the south than in any other easily accessible hight altitude location in the Alps that I have been to.

 



During my visit of the Col du Restefond and subsequently the Silvretta High Alpine Road I used my TMB 115/805 Officiane Stellare Carbon APO on the Celestron CGX Mount and the ASI6200MM Pro camera. As the place is so remote, it is generally a good idea to have a beefy battery pack to power all the gear like the cooled camera, mount, dew heaters and the laptop, as there is no electricity or any charging point nearby. I used a 500Wh LiIon Power Station. Next time I will also carry solar panel to remotely charge the power station.

Coming from the North and the small town of Jausiers the quarry at the Route de Nice is located at an altitude of 2600m, about 1km away from the Cime de la Bonette and the 2800m high peak of this alpine road, very close to the old World War 1 Fortine du Restefond. A stone wall to the West provides some protection against the cold winds. Temperatures in July at night were between -2 and +5°C. Daytime temperatures reached +10°C. Warm winter clothes are a must if you want to spent the night in this altitude. If you need any supply like water, food, electricity, fuel or a shower and rest rooms you have to go to Jausiers, about 25 min down the road. There are public rest-rooms and a small campground with showers and some shady trees. A bigger more comfortable campground and a large supermarket however can be found in Barcelonette further 15 min away. The best option to visit this remote place for astronomy is a motor home or at least a small camper.

Some other French astronomers were also visiting this dark place, as weather during the time was very good, compared to the rainy summer in central Europe and Germany in particular. Due to the topography of the southern French Alps and the Haute Provence and its vicinity to the sunny French Riviera, there is a much higher chance for clear skies compared to the northern parts of the Alps. Unfortunately, due to the altitude, the Col du Restefond can only be visited between May and October, as later in the year snowfall and cold temperatures could prevent a visit. During my visit in early July 2021, much of Europe and the Alps were under a cloud cover, except the Alps in the Park National du Mercantour. From seven nights I had 5 clear nights with no cloud cover at least from midnight to dawn.

 



The Milkyway arch above the mountain range of the French Alps in the Parc national du Mercantour.

Image composition of the Milkyway with 1h exposure time and the foreground taken from a timelapse movie.

The Route du Restefond is climbing up from Jausiers to the Col du Restefond through a high alpine vegetation zone.

 



The Route de Nice to the Col du Restefond coming from the south and the city of Saint-Étienne-de-Tinée