Home=Current Comets
| The German Group
| Tutorials
| Archive: Fainter Comets 2022
| Projects, publications
| Images
| Contact
On images taken on Sep. 15, 2020 the ATLAS team discovered a comet of magnitude 19 in the constellation Caelum. Follow-up observations of comet C/2020 R7 (ATLAS) show a significantly condensed 6" coma of total magnitude 19.0, but no tail. The comet will pass perihelion in the solar distance of 2.96 AU on Sep. 16, 2022 (CBET 4859) and could peak at 13.5 mag in July 2022. However, at that time he will be moving through the far-southern sky. Between October 2021 (positioned in Pavo) and August 2023 it should be brighter than 16 mag. Observers at mid-European locations should be able to observe the comet starting in January 2023 (expected to be of magnitude 15.0). Until August 2023 it will move through the constellations Serpens, Ophiuchus, Hercules and Corona Borealis.
Based on 68 observations from 18 observers the comet showed a very steady development according to the parameters
m0 = 7.2 mag / n = 4
yielding a maximum brightness of 13.7 mag around July 20, 2022. The diameter of the significantly condensed (DC 4-5) coma peaked at 0.8' (100,000 km). A tail of up to 5' (2 mio. km) length, pointing approximately in southeastern direction, could be detected by CCD observers between May and October 2022.
Total Brightness and Coma Diameter
--------------------
The PanSTARRS project discovered a comet of magnitude 20 in the northeastern part of Eridanus on images taken on Sep. 16, 2020. Comet C/2020 S4 (PANSTARRS) showed a coma of only 2" and a 4" tail in p.a. 240° – not surprising, regarding the fact that the comet was 8 AU distant from the Sun. It will pass perihelion in the solar distance of 3.36 AU on Feb. 7, 2023, expected to reach magnitude 15.0 (CBET 4863). It should be brighter than 16 mag between November 2022 and May 2023. During these months it will move through the constellations Cancer and Leo, being well suited for mid-European locations.
This comet reached its maximum brightness of 14.8 mag in early February 2023. Based on 52 observations from 12 observers (until the start of May 2023), the brightness development can be well represented by the parameters
m0 = 5.0 mag / n = 6.
The moderately condensed (DC 4) coma reached a maximum diameter of 1.3' (140,000 km), the westward pointing tail a maximum length of 5' (3.5 mio. km).
Total Brightness and Coma Diameter
--------------------
On images taken by the "Asteroid Terrestrial-Impact Last Alert System (ATLAS)" on Dec. 28, 2020 an asteroidal object of magnitude 17.5 was discovered in the eastern part of Virgo. Follow-up observations showed it to be slightly diffuse. Comet C/2020 Y2 (ATLAS) will pass perihelion on June 17, 2022 in the solar distance of 3.13 AU and could peak at magnitude 14.0 in March 2022 (CBET 4905). It should be brighter than 16 mag between October 2021 and March 2023. During this interval it will move from the southern part of Hydra through Centaurus, Crux, Puppis into the southern part of Cetus. Thus it will not be visible from mid-European locations during this interval.
The comet was of magnitude 14.5-15.0 in spring 2022, showing a medium-condensed coma of diameter about 0.5'. The few published observations hint towards a rather high activity parameter.
--------------------
On Aug. 10, 2021 the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) team discovered an asteroidal object of magnitude 19 in the constellation Cassiopeia, which showed cometary morphology during follow-up observations. Comet C/2021 P4 (ATLAS) showed a strongly condensed coma of diameter 5" and total magnitude 19.5, which was elongated towards p.a. 235°. The comet will pass perihelion on July 30, 2022 in the solar distance of 1.08 AU, expected to peak at 12 mag. Alas, it will be positioned on the opposite side of the Sun, resulting in small elongations (CBET 5024). It should be brighter than 16 mag between March and December 2022. At mid-European locations it will disappear above the northwestern evening horizon at the end of June (then of magnitude 12.5). Worldwide will it be a difficult object during the following weeks. Between March and June it moves through the constellations Cassiopeia, Camelopardalis and Lynx. Thereafter it will move through Cancer, Leo, Sextans, Crater, Hydra towards Ara/Pavo (in December) – but will be situated near the Sun.
This comet showed a development slightly above average. Based on 47 observations from 20 observers the brightness parameters are m0=8.1 mag / n=4.5, indicating a maximum brightness of 10.0 mag by the end of July 22022. The coma diameter increased from 0.5' (65.000 km) to 1.5' (140.000 km). It was moderately condensed with the degree of condensation increasing slightly from DC 3-4 to DC 4-5. Starting in March 2022 a tail was observed, reaching a maximum length of 15' (3 mio. km), which changed its orientation from NE to N. From July 2022 onwards the comet was too near the Sun for observations.
Total Brightness and Coma Diameter
--------------------
Another comet, this time in the constellation Cetus, was discovered by the ATLAS-Team on June 12, 2022. Comet C/2022 L3 (ATLAS) showed a strongly condensed coma of diameter 12" and total magnitude 17.3 and a 30" tail in p.a. 235°. It will pass perihelion at the solar distance of 2.41 AU on Oct. 31, 2022, expected to reach magnitude 15.0 (CBET 5139). It should be brighter than 16 mag between end of August 2022 and mid-January 2023. During this period it moves from near the border of the constellations Cetus/Aries to near the border of the constellations Aries/Triangulum, being well observable from mid-European locations for the whole night. Earth will cross the comet's orbital plane on Oct. 23.
Only 28 observations from 10 observers can be used for a rough analysis. These show a different brightness development pre- and post-perihelion, with the comet brightening faster pre-perihelion than it faded post-perihelion. The comet peaked at 14.5 mag in early November 2022. The estimates can only be simulated with dt-formulae. The following formulae represent the development quite well, with the first formula having a significantly higher correlation:
t < +5d: m = 14.0 mag + 5×log D + 0.029×(t-T)
t > +5d: m = 13.8 mag + 5×log D + 0.006×(t-T)
The apparent coma diameter was fairly constant at 0.8', indicating a slight decrease in absolute diameter from 50.000 km to just under 45.000 km. Estimates of the degree of condensation have not been reported. CCD observers recorded a tail of maximum length 3' (1.2 mio. km) that changed orientation from Southwest towards Southeast during the apparition.
Total Brightness and Coma Diameter
--------------------
On Sep. 14, 2022 the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) team discovered a comet of magnitude 17 in the constellation Gemini. Comet C/2022 R2 (ATLAS) showed a highly condensed 20" coma of total brightness 16.5 mag and a 1.5' tail in p.a. 280°. It will pass its close perihelion (solar distance 0.63 AU) on Oct. 25, 2022, expected to reach magnitude 14.5 (CBET 5171). However, it will be positioned near the Sun during these days. In addition the absolute magnitude of 15.5 mag is several magnitude fainter than the Bortle-limit. Thus there exists a high probability that the comet will disintegrate while approaching the Sun. If it should survive the solar passage it should be brighter than 16 mag between mid-September and mid-November 2022. During this period it will move through the constellations Gemini, Cancer, Leo, Coma Berenice, the southwestern parts of Bootes towards the eastern corner of Virgo. At mid-European locations its altitudes will decrease from 40° to 5° during this period.
This comet could only be tracked during a short period before it disintegrated (as expected). A total of 15 observations from 6 observers covered just one month. The brightness estimates cannot plausibly be represented by a standard formula. After an initial rapid brightening while approaching the Sun the comet peaked at 12.2 mag on Oct. 9, 2022. During the following two weeks – with the comet still approaching the Sun - the comet faded more and more rapidly, indicating that the comet had disintegrated.
Until Oct. 9 the coma diameter increased from 1.0' (50.000 km) to 2.0' (90.000 km). Thereafter it shrank very rapidly, measuring just 0.5' (20.000 km) at the end of the apparition. Estimates of the degree of condensation have not been published. Throughout the short apparition a tail of length 5' (250.000 km) was detectable, which changed its orientation from WNW towards NNW.
Total Brightness and Coma Diameter
--------------------
Comet 9P/Tempel (P=5.58a) passed perihelion on Mar. 4, 2022 at a solar distance of 1.54 AU, but could not be observed from mid-European locations.
Based on only 20 observations from 8 observers the brightness parameters can only be derived roughly to m0=9.0 mag / n=8, meaning a maximum brightness of 14.0 mag around perihelion. The coma diameter reached 0.8', the degree of condensation DC 3. No tail was observed.
--------------------
Comet 22P/Kopff (P=6.38a) passed perihelion on Mar. 18, 2022 at the solar distance of 1.55 AU. The comet may be observed from mid-European locations from early July onwards, then expected to be of magnitude 12.5. It is moving near the border of the constellations Pisces/Cetus, being an object in the morning sky.
The published estimates show a surprisingly large scatter. Based on 87 observations from 21 observers brightness parameters of
m0 = 6.5 mag / n = 7
result. Thus the comet peaked at magnitude 11.5 at the end of March 2022. Until early August 2022 it had faded to 13.5 mag. The coma diameter was 1.3' (130.000 km) at the start of the apparition, increasing to the maximum of 2.8' (180.000 km) at the opening of August 2022. Estimates of the degree of condensation are very rare, indicating DC 2, i.e. the coma was very diffuse which may explain the large scatter of the estimates. Equally rare were observations of the tail (between mid-April and end of August), which reached 10' (1.5 mio. km), pointing constantly WSW.
Total Brightness and Coma Diameter
--------------------
Surprisingly bright appeared comet 45P/Honda-Mrkos-Pajdusakova (P=5.33a) just after its perihelion passage (April 25, 2022 at the solar distance of 0.56 AU). Its absolute magnitude was 3 mag brighter compared to previously observed perihelion passages. Based on only 25 observations from 11 observers the brightness parameters are approximately m0=8.2 mag / n=5 and the maximum brightness of 6.0 mag was reached during perihelion. As usual for this comet the brightness decreased rapidly during the following weeks, reaching 11.0 mag by the end of June 2022. The diameter of the coma was around 3.5' (250.000 km) at perihelion. Between May 20 and June 10 it decreased from 5' (325.000 km) to 2' (150.000 km). The degree of condensation decreased very rapidly, which is typical for this comet too. On May 16 it was estimated at DC 6, but only at DC 2 on May 31. The eastward pointing tail decreased comparably fast from its maximum length of 12' (1.3 mio. km) on May 20. The comet was unobservable from mid-European locations.
Total Brightness and Coma Diameter
--------------------
In late summer and fall 2022 comet 61P/Shajn-Schaldach (P=7.09a) should become brighter than 16 mag. It will pass perihelion in the solar distance of 2.13 AU on Oct. 23, 2022, expected to reach magnitude 14.0-14.5. It makes an opposition loop near the border of the constellations Pisces/Cetus, being observable during the whole night during the weeks around perihelion. It should get fainter than 16 mag during the second half of January 2023.
Only a small number of observers followed the development of this comet, probably due to its faintness. The comet peaked at only 14.5 mag around Oct. 20, 2022. Based on only 28 observations from 13 observers the brightness development can only be represented by using time-dependent formulae. The comet brightened considerably faster pre-perihelion than it faded post-perihelion, according to the formulae
t < -5d: m = 14.1 mag + 5×log D + 0.050×(t-T)
t > -5d: m = 14.4 mag + 5×log D + 0.016×(t-T)
Pre-perihelion the coma diameter increased similar fast as it decreased post-perihelion, reaching a maximum of 1.5' (75.000 km). No DC-estimates came to my knowledge. No tail was observed.
Total Brightness and Coma Diameter
--------------------
Comet 81P/Wild (P=6.41a) should get observable in mid-September 2022 in the morning sky. It passes perihelion at the solar distance of 1.59 AE on Dec. 15, 2022. The comet moves in southeastern direction from the constellation Leo into Virgo. It should brighten from 13.0 mag to 11.0 in mid-November and should peak at 10.5 mag in mid-December 2022.
All in all 189 observations from 34 observers can be used for the analysis. They indicate a different development pre- and post-perihelion. While the pre-perihelion development can be described very well with the following formula, the development after perihelion is difficult to reproduce with one formula. The reason seems to be that the comet experienced a significant drop in activity shortly after perihelion, only to partially recover during the following weeks. The appropriate parameters are:
pre-perihelion: m0 = 5.0m / n = 9
post-perihelion: m0 = 7.0m / n = 6.5
The comet peaked at magnitude 11.0 around Dec. 20, 2022. The apparent coma diameter increased from 1.5' at the beginning of the apparition to the maximum of 2.3' in November/December 2022, thereafter steadily decreasing to 1.0' at the end of the apparition. The absolute coma diameter steadily decreased from 200,000 km at the start of the apparition to 55,000 km at the end of the apparition. In parallel, the coma became steadily more diffuse; the degree of condensation decreased from DC 4-5 to DC 2-3 during the apparition. A westward-pointing tail of up to 7' (1.5 mio. km) length was reported between late October 2022 and late March 2023.
Total Brightness and Coma Diameter
--------------------
Comet 116P/Wild (P=6.51a) will pass perihelion at the solar distance of 2.19 AU on July 16, 2022, expected to peak at magnitude 13.0 at the start of April 2022. During winter/spring 2022 it loops in eastern Leo.
The comet peaked at magnitude 13.5 at the end of March 2022. While it still approached the Sun until mid-July, it receded from Earth since February, resulting in a slow decrease in apparent brightness from April onwards. Based on 104 observations from 29 observers the brightness parameters m0=4.8 mag / n=8.5 result. The coma diameter increased from 0.7' (60.000 km) in early January 2022 to its maximum of 1.5' (110.000 km) in early April, only to decrease again until the end of June to 1.0' (95.000 km). The degree of condensation was quite constant at DC 3-4. A tail of up to 3' (1 mio. km) length was observed throughout the whole apparition. It was oriented towards WNW until Mar. 10, pointing towards ESE from Mar. 25 onwards. From July 2022 onwards the comet was too near the Sun for observations.
Total Brightness and Coma Diameter
--------------------
Comet 117P/Helin-Roman-Alu (P=8.26a) will pass perihelion on July 7, 2022 at the solar distance of 3.04 AU. The comet is moving in the southern parts of the constellation Sagittarius and remains therefore at very low altitudes for mid-European locations.
Due to the very small variance in solar distance (only 0.05 AU) the brightness development of this comet is rather undefinable, despite the used 38 observations from 9 observers (until mid-November 2022). In addition the estimates show a rather large scatter. The most plausible parameters are m0≈7.0m / n≈4. In every case the comet peaked at magnitude 13.3 at the opening of July 2022 (near perihelion date). Until now the coma diameter measured between 0.5' (50.000 km) and (in June) 0.7' (70.000 km). The coma was significantly condensed (DC 5). No tail was observed.
Total Brightness and Coma Diameter
--------------------
Comet 118P/Shoemaker-Levy (P=6.12a) will pass perihelion in the solar distance of 1.83 AU on Nov. 24, 2022, expected to reach magnitude 13. Between mid-August and mid-November 2022 it moves from the border of the constellations Orion/Gemini towards the border of the constellations Cancer/Hydra, thereafter will turn northward towards M 44 until March 2023. During the first period it should brighten from 15.5 mag to 13.5 mag, and will start to fade in January 2023.
A total of 94 observations from 20 observers can be used for the analysis, which, however, show a rather large scatter. Therefore the brightness development can only be simulated moderately well with the formula
m = 10.2 mag + 5×log D + 12×log r.
Thus the comet reached a maximum brightness of about 13.0 mag in mid-January 2023, thereafter fading below 16 mag until early May. The diameter of the diffuse (DC 3) coma increased from 1.0' (70,000 km) at the start of the apparition to the maximum of 2.2' (90,000 km) in January 2023, thereafter decreasing to 0.7' (70,000 km) until the end of April. A westward pointing tail of 5' (1.5 mio. km) maximum length was observed between late October 2022 and late February 2023.
Total Brightness and Coma Diameter
--------------------
On Aug. 11, 2022 comet 119P/Parker-Hartley (P=7.42a) passed perihelion in the solar distance of 2.33 AU. Because it approaches Earth until the turn of 2022/23 it will peak at magnitude about 15.0 at these days. In winter 2022/23 the comet moves from the border of the constellations Cancer/Gemini towards the central part of Gemini. Thus it will be a comfortably positioned object of the whole night.
The comet showed an interesting brightness development, which however is based on only 27 observations from 10 observers. The activity of the comet continued to increase until 140 days after perihelion (Dec. 29, 2022). Only thereafter did it start to decrease. The development can only be simulated with time-dependent formulae, with the first being much worse defined than the second:
t < +140d: m ≈ 16.0 mag + 5×log D – 0.025×(t-T)
t > +140d: m = 10.5 mag + 5×log D + 0.015×(t-T)
The maximum brightness of about 13.5 mag was reached at the turn of 2022/23. In early April 2023 the comet became fainter than 16 mag. The diameter of the moderately condensed (DC 3...4) coma increased from 0.5' (45,000 km) at the start of the apparition to the maximum of 1.3' (100,000 km) in February 2023, thereafter decreasing to 0.7' (90,000 km) by mid-April. Sightings of the westward pointing tail were very rare, indicating a maximum length of 3' (2 mio. km).
Total Brightness and Coma Diameter
--------------------
Comet 169P/NEAT (P=4.20a), not visible from mid-European locations during this apparition, passed perihelion in the solar distance of 0.60 AU on July 9, 2022, when it peaked at magnitude about 13. This comet shows a high activity parameter, so it brightens and fades rapidly. During the weeks around perihelion it was situated near the Sun and thus difficult to observe.
--------------------
Comet 285P/LINEAR (P=6.12a), which will pass perihelion in the solar distance of 1.72 AU on Jan. 12, 2023, experienced a major outburst at the opening of August 2022. On July 28 it was of magnitude 20.5, but observations by the ATLAS team showed it at magnitude 16.0 on Aug. 1. On Aug. 5 and 6, respectively, it had brightened to magnitude 15.0 (CBET 5155). The future development is unclear.
Regarding the faintness of the comet the large outburst is surprisingly well documented by 56 observations from 21 observers. The very rapid brightening peaked at magnitude 14.7 on Aug. 6, 2022. During the following weeks the comet faded according to the formula m = 18.3m + 5×log (delta) + 0.027×|t-T|. The time-dependant fading of the heliocentric magnitude is typical for a short-term outburst. In parallel the coma diameter decreased continuously from the maximum of 0.8' (55.000 km). Alas no estimates of the degree of condensation have been published. During the first three weeks after the outburst the CCD observers could detect a very short tail.
Total Brightness and Coma Diameter
Andreas Kammerer
