Astronomy

WWW.ASTRONOMY.COM 63

was also close to its maximum possible tilt
toward Earth. We feared the planet’s low
altitude in the sky might limit our results.
In the end, the sessions imaging Saturn
into the early morning hours were perhaps
the highlight of our nights’ work.
While Saturn never rose above 25°, the
exceptional conditions that can prevail at
Pic du Midi were in full effect. The
second night produced seeing con-
ditions of exceptional
quality. Never have I
observed a planet so
still at such low alti-
tude. Even when Saturn
dropped to just 18°, the
image remained razor
sharp and still — a
remarkable thing to witness, especially
when you consider we were using
42 inches of aperture.
While imaging the ringed planet, we
could see minor details such as the Encke
Division, a 200-mile-wide gap within
Saturn’s A ring. But after we processed our
images, we realized we had gotten some
really exceptional data, perhaps resulting
in the sharpest ground-based image of the
planet ever taken.

Dawn approaches
Once our Saturn observations were com-
plete in early morning, just before twilight
began, we shifted our attention to Neptune.
One of the mission’s objectives was to cap-
ture images of the planet early in its appa-
rition, as it was still quite low in the dawn
sky. It marked a great opportunity to be the
first to detect recent activity on the planet
(since it emerged from the Sun’s glare), and
we got lucky on both mornings.
We swapped cameras to use the highly
infrared-sensitive ASI290MM camera,
which works great for imaging the distant
ice giants. We took several runs in

near-infrared wavelengths, and on both

mornings, we saw strikingly bright storms

on the planet. This made our team the first

to detect new features during the first part

of the planet’s apparition. We also obtained

one early image of Uranus, but we could

not detect anything on the planet aside

from the familiar bright polar region.

As the sky brightened with the

approaching dawn, we moved on to Venus,

blazing away brilliantly in the east. By this

time, those of us remaining were feeling

pretty tired, but it was worth the effort. We

took some fine images of the planet, espe-

cially through ultraviolet filters, clearly

revealing its familiar cloud patterns.

Observations continued beyond sunrise,

until we finally closed up and powered

down about an hour later.

Mission accomplished

Having completed the processing for all

the data, our team views the mission as a

resounding success. We were indeed fortu-

nate with the weather conditions, but the

commitment of each member to maximize

every available moment really helped to

deliver the results you see here.

On a personal note, Pic du Midi

Observatory is a remarkable place to

observe from, not only for the superb

astronomical conditions, but also the

spectacular natural scenery visible in

every direction. We never got tired of the

breathtaking views, especially during

dawn and dusk when the lighting and col-

ors were spectacular.

The continuation of a long tradition of

planetary imaging from this historic obser-

vatory looks assured. As I thought back to

the results of astronomers such as Lyot,

Audouin Dollfus, and Henri Camichel, I

certainly felt a connection with those

famous observers who also spent many

memorable nights here pondering the

details they saw through the telescopes.

Modern technology, such as high-speed

cameras coupled with sophisticated image-

processing software, has given this obser-

vatory a whole new lease on life to continue

to produce astounding planetary images. I

can only see a bright future both for the

observatory and the historic T1M tele-

scope, and I look forward to returning. As

the saying goes: Vive le Pic!

Damian Peach, a longtime contributor to

Astronomy, is one of the world’s finest imagers

of planets and comets.

1

3

Even when Saturn had dropped to just

18°, the image remained razor sharp

and still — a remarkable thing to

witness, especially when you consider

we were using 42 inches of aperture.

1. The team imaged Venus through infrared and
   ultraviolet filters June 11, 2017. They captured the
   exposures to create this image between 4h36m
   and 4h51m UT. D. PEACH/E. KRAAIKAMP/F. COLAS/M. DELCROIX/
   R. HUESO/C. SPRIANU


2. Neptune appeared full of features on the
   second and third mornings. Note the bright
   storms visible on the planet, the first discovered
   for this apparition. The team captured this image
   June 12, 2017, at 2h39m36s UT. D. PEACH/E. KRAAIK AMP/
   F. COLAS/M. DELCROIX/R. HUESO/C. SPRIANU/G. THERIN


3. This image of Saturn was captured June 11,
   2017, at 1h22m54s UT, under excellent seeing
   conditions. Many rarely seen details, such as the
   fine ringlets within the planet’s C ring, are visible.
   D. PEACH/E. KRAAIKAMP/F. COLAS/M. DELCROIX/R. HUESO/C. SPRIANU/G. THERIN

2