26/07/2022 19:45-20:28 UT; 29/07/2022 21:41-21:52 UT
Total exposure time:
Skygems Remote Observatories - Hakos, Khomas, Namibia
ASA H8 Hyperbolic 203/592 mm
Focal ratio, length:
f/2.9, 592 mm
L, R, G, B, Ha
4 x 180 s Lum, 2 x 180 s R/G/B, 2 x 300 s Ha
Astro Pixel Processor, PixInsight, Adobe Lightroom, Adobe Photoshop
After the comets C/2020 F3 (NEOWISE) in 2020 and C/2021 A1 (Leonard) in 2021, 2022 will be another interesting one, but not as spectacular as the previous two comets.
C/2017 K2 (PANSTARRS) was discovered on 21 May 2017 by Richard Wainscoat and colleagues using the 1.8-metre telescope of the Pan-STARRS (Panoramic Survey Telescope and Rapid Response System) sky survey programme from the Maui Island in the Hawaiian Islands. From the first images, it was obvious that it was moving relatively slowly, so it was concluded that a distant object had been detected. Calculations soon showed that the hypothesis was correct, with the comet discovered at a distance of 2.4 billion kilometres from the Sun. And further calculations revealed that C/2017 K2 (PANSTARRS) probably came to us from a distance of 0.8 light years, from the Oort cloud. What makes this comet special is that comets are very rarely active at this distance from the Sun. This may also mean that it is probably the first time it has approached the Sun, as the gases, which are volatile even at low temperatures, would have already left the surface of the nucleus on a previous solar approach. Researchers were able to identify the celestial wanderer, which is about 14-18 km in diameter (a pretty big comet), by July 2013, after reviewing archival images.
Following its discovery, its brightness and apparent diameter have increased steadily and predictably. These suggested that a "fresh" comet of 6-7 magnitude brightness would be seen in the summer of 2022. Taking advantage of its approach, on 3 May 2021, I took my first photo of the "dirty snowball", then 920 million kilometres from Earth. The then 13.1 magnitude "resurgent" C/2017 K2 (PANSTARRS) did not hold many surprises, but at the time there was no sign that the previously stable comet would fall slightly short of expectations.
In the spring of 2022, the light curve already showed some signs of a break and by early summer it became clear that we could expect the comet to reach 7.5-8 magnitude during its visibility in Hungary. The lack of a long tail and the compact green coma are a distinct disappointment for a comet that has rarely or never been close to the Sun. The comet, which can be observed with binoculars and is heading steeply south, was visible in the constellation of Ophiuchus and Scorpius in the summer and later exclusively from the southern hemisphere.
The comet, which was observable with binoculars and heading steeply south, produced spectacular conjunctions in the embrace of emission nebulae and said goodbye to Ophiuchus, one of the largest constellations in its area, where it was observed for more than two months. On the evening of 26 July 2022, I captured an encounter with the emission nebulae LBN 35, LBN 39 and the dark nebula LDN 238 using a Namibian robotic telescope. A few days later, I repeated my observation of the same part of the sky and collected narrowband data to reveal the red-colour nebulae even more spectacularly.
C/2017 K2 (PANSTARRS)
R.A. 16 h 35 m 22 s Dec. -8° 33′ 55″
Distance from Sun:
381 million km
Distance from Earth:
275 million km
Coma: 8'; Dust tail: 55' (PA: 18°); Gas tail: 20' (PA:120°)