Astronomy

WWW.ASTRONOMY.COM 61

decided to form a small, dedicated team
of experienced planetary observers — of
whom I was one — who would use the tele-
scope more regularly for planetary studies.
Thanks to funding from Europlanet,
the team decided suitable dates for the pro-
totype mission. We chose June 2017
because Saturn would be close to opposi-
tion, Jupiter would be well placed in the
early evening, and Uranus, Neptune, and
Venus would also be visible toward dawn.
The group met at Toulouse Airport. We
then packed into two cars for a three-hour
drive to the small town of La Mongie. The
journey through this region was spectacu-
lar, passing through mountainous scenery
and small country villages. As we reached
La Mongie, we broke through a sheet of
low clouds into blazing sunlight. From
here, we transported several boxes of food
and drink for the stay.
The cable car journey from La Mongie
to Pic du Midi is not for those with a fear
of heights! On the slow ascent up the
mountain face, we were often suspended
high above mountainous ravines. The view
was spectacular, though, with low clouds
below and jagged mountain peaks as far as

the eye can see.

Eventually we

reached the first

cable car station,

where we disem-

barked and moved

to a second cable

car for the final

ascent to the sum-

mit. At this point,

we could clearly see

the observatory

perched atop the

mountain. When it first

came into view, I wondered

how an observatory could be built

at such a site.

Upon arriving, we took all of our

equipment and supplies to the laboratory.

Our team stayed at the astronomers’ lodg-

ings, which consist of several small rooms

with beds and wash facilities in a quiet

area several meters below the telescope

domes. We took some time to prepare for

the first night’s observations, which would

begin at sunset.

The 1.06m telescope, or T1M as it’s

known, isn’t at all like your typical large

amateur scope. Because it was built in the

’60s, many of its control systems take time

to learn. So we spent some of that first eve-

ning prior to sunset learning how to oper-

ate the telescope, which was a key part of

our mission. The telescope is operated

from the laboratory directly below the

dome, but the initial setup of locating the

target object and installing the camera has

to be done in the dome itself. Locating the

target proved quite challenging, mainly

because it involved climbing a tall ladder

to reach the finder scope’s eyepiece. Colas’

many years of using the telescope were

invaluable here.

Jupiter imaging

After a delicious evening meal prepared

by Colas, we walked across to the western

side of the observatory to watch the sunset,

always a spectacular sight at this amazing

location. Then we quickly walked back

to T1M, where we would spend the next

three nights.

From the wide range of cameras and

filters to choose from, we ended up using a

ZWO ASI174MM monochrome CMOS

camera for most captures, but we also used

the ASI224MC (color) and ASI290MM

(monochrome) cameras. We made sure to

bring large amounts of memory storage

for what we hoped would be a productive

few days. As it turned out, we had just

enough space for all

the data we would

eventually capture.

Each evening began with

Jupiter. Although well past oppo-

sition, the planet was situated high in the

southwest, and we spent the first couple of

hours imaging it. The first night, we dealt

with quite a few thick, high cirrus clouds,

but we were able to obtain good images.

The second and third evenings, however,

produced far better conditions that resulted

in some extremely detailed images.

Although we obtained images through

various filters on all the cameras, the best

results were in the near-infrared wave-

lengths, where the resolution was remark-

able. During the three nights, we covered

most longitudes of the planet and obtained

high-resolution images that would later

allow us to measure wind speeds in

Jupiter’s atmosphere.

Through the night

Once we finished with Jupiter, we moved

on to Saturn. This meant heading back up

to the dome to move the telescope, recali-

brate the dispersion corrector, and take a

few peeks through the eyepiece.

Saturn was only a few days from oppo-

sition during our mission. The ring system

The team obtained this

spectacular 13-minute

exposure of Jupiter

on June 11, 2017,

at 21h57m24s UT.

The planet reveals

a wealth of fine

detail within its

atmosphere. D. PEACH/

E. KRAAIKAMP/F. COLAS/

M. DELCROIX/R. HUESO/

C. SPRIANU/G. THERIN

Ganymede, Jupiter’s largest moon, was in the

team’s crosshairs on the second evening. Even

though the satellite’s diameter spanned a scant

1.42", this image shows many clearly identifiable

features. The team shot through infrared and

RGB filters June 10, 2017, at 21h42m UT. E. KRAAIKAMP/

D. PEACH/M. DELCROIX/G. THERIN/C. SPRIANU/R. HUESO/F. COLAS