Comet rendezvous from Chile

C/2020 F3 (NEOWISE)

On March 27, 2020, for the inhabitants of the northern hemisphere, the most spectacular comet of the past two decades was discovered by NASA’s infrared space telescope program (NEOWISE). It was an exciting spring, as after two hopeful, eventually disintegrating comets, we hoped this comet would survive its perihelion.

The really great excitement began on June 22, 2020, when a comet heading for its perihelion (44 million kilometers from Sun) appeared on SOHO’s solar recordings. In the images of the spacecraft, a “healthy” and brighter-than-expected comet was observable. Barely ten hours after the perihelion, at dawn on July 4, 2020, we were able to observe for the first time from Hungary. The comet was almost lost in the light of dawn and could be seen only at a height above the horizon of 4-5 degrees.

The following mornings were in an increasingly favorable position and fortunately there was no complaint about the weather. The appearance of a comet with a magnitude of about 1.5-2 quickly crawled through the press and more and more professionals and laymen turned their cameras to the sky. For the under-thirty (even if some saw C/1995 O1 (Hale-Bopp) as a toddler), it was the long-awaited comet. As a teacher, I saw it as one of the greatest opportunities of my life, as spending my summer vacation could only be prevented by the weather. I vowed to take pictures of our celestial wanderer whenever I could (result: 48 days, 18 nights photographed, 122 GB of data, 3766 image files).

Each occasion had its own charm. At dawn on July 8, 2020, it was observed along with an amazingly sized NLC (night illuminated cloud) that if one saw with their own eyes, one would not forget for a lifetime. The tail grew longer and longer and its curvature became clearer day by day. It was a great pleasure to be able to deploy my telescope for the first time on July 11, 2020, with which I could detect even a faint gas tail at the time. On July 13, I had my last morning observation. After that, I tried in the evening sky. By photographing the comet, which had become circumpolar, my trouble accumulated in the following weeks. Unfortunately, with a few exceptions, it was an overcast or veiled sky that made it impossible to take photographs. The full moon in early August didn’t really help either, by the time its phase had diminished, by which time the comet had faded quite a bit, looked lower and was starting to take on the look typical of average comets (round green coma). I did my last observation on the evening of August 20, 2020, when I estimated its brightness to be only 7.4 magnitude, and its appearance was a shadow of July itself.

The fading comet C/2020 F3 (NEOWISE) has encountered several galaxies and globular clusters in early August 2020, but the most special for me was the conjunction with another comet. The cloudy nights in August not only annoyed the comet hunters in Hungary, as there was no shortage of clouds at the most famous remote observatory sites. I wanted to capture a lot of spectacular coexistence - mostly my own eqipment, but I only had the opportunity to photograph this comet meeting from Chile.
At dawn on August 12, 2020, I had a very short time window with the remote-controlled Chilescope VST system, as the comets were 1-2 degrees above the 30 degree set limit, so I was very lucky to be able to finish the picture at all. I estimated the total brightness of the C/2020 F3 (NEOWISE) comet to be 6.7 magnitude, the tails getting shorter and fainter.

Another participant in the comet rendezvous is the comet C/2017 T2 (PANSTARRS) with a magnitude of 10.7, which has become known in the last six months. This comet also produced beautiful conjunctions, which I managed to capture one after another, but for me it still became the most special. Interestingly, the two comets were apparently very close (about 160'), but were physically separated by 190 million km, which is more than the distance between the Sun and the Earth.

Image processing was hampered by the minimal signal-to-noise ratio that the photograph had to be registered not only for the stars but also separately for the two comets.


C/2020 F3 (NEOWISE)




R.A. 13 h 35 m 46 s Dec. +11° 19′ 42″



Distance from Sun: 

158 million km

Distance from Earth:

162 million km

Apparent size:

Coma: 7';
Dust tail: 3° (PA 65°); Gas tail: 4° (PA 95°)



Sidereal period:

6,900 years


41 km/s


11/08/2020 23:35-23:43 UT

Total exposure time:

5 minutes


Chilescope - El Sauce Observatory, Río Hurtado, Chile


FLI MicroLine 16200


Chilescope VST - Nikon 200 mm f/2


10Micron GM1000HPs



Focal ratio, length:

f/2, 200 mm


2 x 60 s Lum, 1 x 60 s R, 1 x 60 s G, 1 x 60 s B



Dark Flat:







Astro Pixel Processor, PixInsight, Adobe Lightroom, Adobe Photoshop




Locations in the Solar System

C/2020 F3 (NEOWISE) and C/2017 T2 (PANSTARRS) - 12/08/2020 (Robotic)

Main objects: C/2020 F3 (NEOWISE), C/2017 T2 (PANSTARRS)






R.A. 13 h 43 m 41 s Dec. +13° 11′ 48″



Distance from Sun: 

311 million km

Distance from Earth:

352 million km

Apparent size:

Coma: 2'; Tail: 18' (PA 340°)



Sidereal period:

233,474 years


29 km/s


C/2020 F3 (NEOWISE)