Home=Current Comets
| The German Group
| Tutorials
| Archive: Fainter Comets 2016
| Projects, publications
| Images
| Contact
On Nov. 17, 2014 the PanSTARRS team discovered a comet near the border of the constellations Taurus/Orion. The brightness of the not-stellar coma of comet C/2014 W2 (PanSTARRS) was estimated to be 18.5 mag. Additional observations showed a 20" coma of magnitude 17.5 and a faint tail pointing towards SSW. The comet will pass perihelion at the beginning of March 2016 (CBET 4019 / MPEC 2015-B177). Assuming an average brightness evolution the comet should peak at 13.5 mag at the beginning of 2016. It should be brighter than 16.0 mag between July 2015 and November 2016. During this period it will move through the constellations Auriga, Camelopardalis, Ursa Minor, Draco, Bootes and Serpens.
14 observations from 4 members of the German Comet Section together with 95 international observations can be represented well with the brightness formula m = 6.6 mag + 5×log D + 9.5×log r. This yields a maximum brightness of 12.8 mag at the turn of 2015/16. However, between mid-November 2015 and mid-June 2016 the comet was less than 0.2 mag fainter. Until March 2016 the coma diameter was estimated between 0.5' (70.000 km) and 0.8' (100.000 km). Thereafter it increased, peaking at 1.7' (200.000 km) in mid-June. Thereafter it decreased slowly. The degree of condensation varied between DC 3 and DC 4 until April 2016. It then increased to DC 5 until mid-May, decreasing to DC 4 in mid-August. No tail could be glimpsed visually.
Total Brightness and Coma Diameter
--------------------
An asteroidal object of magnitude 21, already discovered by the PanSTARRS project on Nov. 17, 2015 near the border of the constellations Taurus/Eridanus showed cometary morphology when observed in mid-April 2016. Comet C/2015 WZ (PanSTARRS) showed a 1.9' coma of total magnitude 13.0 and a 1.4' tail in p.a. 282°. It passed perihelion in mid-April 2016 (CBET 4273) and should peak in May/June 2016 at about magnitude 12.5.
The number of observations published is far too small to derive definite values for the brightness parameters. The observations favor the brightness parameters. m0=9.5 mag / n=4, yielding a maximum brightness of 12.0 mag in June 2016. In May the coma diameter was estimated at about 2.0-2.5', with the coma being rather diffuse (DC 2).
--------------------
An asteroidal object of magnitude 20, discovered by the LINEAR project on Jan. 14, 2016 in the constellation Andromeda showed cometary morphology on follow-up observations. Comet C/2016 A8 (LINEAR) displayed a strongly condensed 6" coma of total magnitude 19.0 and a faint fan-shaped 10" tail in p.a. 70°. It will pass perihelion on its elliptical orbit with a period of about 220 years at the end of August 2016, when it may reach 15.0 mag (CBET 4245). It should be brighter than 16.0 mag in August and September, when it will move from Andromeda into Aquila, being observable during the whole night. Only 40 observations could be used for the analysis. They indicate a very large activity parameter. The brightness evolution can be simulated with the formula m = 1.7 mag + 5×log D + 40×log r, yielding a maximum brightness of 12.5 mag at the start of September 2016. The coma diameter showed an equally rapid evolution. Measuring 0.5' (30.000 km) at the start of August it reached short of 1.0' (50.000 km) at the opening of September, thereafter decreasing to 0.5' (30.000 km) until the beginning of October. The coma was medium-condensed (constant DC 4).
Total Brightness and Coma Diameter
--------------------
An asteroidal object of magnitude 19.5, discovered by the PanSTARRS-team on Jan. 22, 2016 in the constellation Columba, showed a tail on images taken on Feb. 10. Detailed observations of comet P/2016 BA14 (PanSTARRS) showed a 10" tail in p.a. 65° and a stellar head. The comet will reach perihelion on Mar. 15 and perigee (0.024 AU) on Mar 23. Assuming a standard evolution the comet could peak at magnitude 13.0. Its orbit is very similar to that of comet 252P/LINEAR (CBET 4257)! It should be brighter than magnitude 16.0 between Mar. 11 and Apr. 2, thereby moving from Canis Major into Hercules. The very few published visual and CCD observations hint towards a maximum brightness of the nearly stellar coma of 13.0.
--------------------
On Sep. 11, 2016 Gennady Borisov discovered a comet in the northwestern corner of Leo with the 0.3m-astrograph of Krim observatory, estimating its brightness to be 16.0 mag, with a coma diameter of 0.5'. Alan Hale could observe comet C/2016 R3 (Borisov) visually with his 41cm-reflector on Sep. 14. He estimated it to be of magnitude 12.9, showing a 1.4' coma; however, the comet was only visible in twilight at an altitude of 14° in front of the zodiacal light. The comet passed perihelion (at a solar distance of only 0.45 AU) on Oct. 10, expected to have peaked at 10.0 mag. However, during these days it was too near the Sun for observations. Maik Meyer pointed to the similarity of the orbital elements of this comet with those of comet C/1915 R1 (Mellish) = 1915 II. The available observations for C/2016 R3 are consistent with intermediate-period orbits with periods as short as 50 years, possibly even 30 years. However, attempts to link the observations of 1915 and 2016 (with 0, 1, 2, 3 potential missed returns) have not been successful (CBET 4321).
--------------------
On Nov. 6, 2016 the PanSTARRS team discovered comet C/2016 VZ18 (PanSTARRS) as an asteroidal object of magnitude 22 near the border of the constellations Eridanus/Cetus/Fornax (CBET 4351). At the end of December 2016 its cometary nature was detected and a maximum brightness of 16-17 mag predicted. However, at the end of February 2017 the comet was 3 mag brighter. It peaked at magnitude 13.5 in mid-March 2017, showing a very diffuse (DC 1) coma of diameter about 1.5'. Thereafter it faded rapidly.
--------------------
In spring 2016 comet 9P/Tempel (P=5.58a) will be observable with medium-size telescopes. At perihelion (start of August) it should peak at about 12.0 mag, but will be less than 10° above the evening horizon for mid-European observers during the second half of 2016. It moves from Coma Berenices into Leo.
Although I could use 60 observations for the analysis, they show a large scatter. Thus the derived brightness parameters m0=6.5m / n=10 are rough values, yielding a peak brightness of 12.0 mag between mid-June and mid-August 2016. The estimates of the coma diameter are in the order of 1.0' to 1.5', the degree of condensation was estimated between DC 3 and 4.
--------------------
Comet 43P/Wolf-Harrington (P=6.13a) will appear in the morning sky in mid-August 2016, at an expected magnitude of about 11.0. Until the beginning of October it will move from Gemini into Sextans, thereby fading.
For the analysis of the apparition 2016/17 I could use 60 observations. These imply a brightness evolution according to the formula m = 7.5 mag + 5×log D + 17.5×log r, yielding a maximum brightness of 11.3 mag at perihelion. The coma diameter increased from 0.6' (65.000 km) at the start of the apparition to the maximum of 2.0' (190.000 km) at the end of September 2016. Thereafter it shrunk rapidly at first, reaching 0.9' (75.000 km) at the end of October. During the following weeks the decrease slowed with the coma measuring 0.7' (45.000 km) at the beginning of February 2017. During the whole apparition the coma was rather diffuse (degree of condensation constant at DC 3).
Total Brightness and Coma Diameter
--------------------
With medium-sized instruments observers could try to find comet 53P/Van Biesbroeck (P=12.59a) in spring 2016. It is situated near the border of the constellations Aquarius/Capricornus and should be an object of magnitude 13.
For a rough analysis 47 observations could be used. The brightness estimates can be rather well represented by the parameters m0=8.2 mag / n=4, yielding a maximum brightness of 13.0 mag in mid-July 2016. Until August the coma diameter increased from 0.5' (50.000 km) to the maximum of 1.2' (85.000 km), only to decrease thereafter, reaching 0.7' (75.000 km) at the end of October. During most of the apparition the coma was medium-condensed (DC 3), but became more diffuse during October.
Total Brightness and Coma Diameter
--------------------
In spring 2016 comet 77P/Longmore (P=6.88a) should be observable in medium-size instruments. At perihelion in mid-May it should peak at 13 mag. It is situated in Corvus.
A rather small number of published observations do not allow to derive definite values for the brightness parameters. However, the values m0=5.0 mag / n=8 are at least plausible, indicating a maximum brightness of 13.0 in mid-April 2016. The diameter of the medium-condensed (DC 4) coma measured about 0.8'.
--------------------
During winter 2015/16 comet 81P/Wild (P=6.41a) should become visible in medium-sized instruments. The comet loops in Taurus, being observable during the whole night. The comet is expected to peak at magnitude 12.0 in spring 2016; however the brightness evolution is still uncertain.
The analysis can be based upon 27 observations from 6 observers of the German Comet Section and 80 international observations. Accordingly the brightness evolution shown can be rather well represented by the parameters m0=5.3 mag / n=8, yielding a maximum brightness of 11.1 mag in early July 2016. The coma diameter increased between mid-November 2015 and July 2016 from 0.5' (40.000 km) to 3' (300.000 km). The coma was extremely diffuse (DC 1-2) at the start of the apparition, condensed until the opening of March, when it reached DC 4, thereafter became more diffuse, reaching DC 3 at the end of July. Visually a tail could not be detected.
Total Brightness and Coma Diameter
--------------------
40 observations of comet 116P/Wild (P=6.51a) can be used to analyse the apparition 2016. These however, allow only the calculation of rough values for the brightness parameters, hinting towards m0=8.5 mag / n=4. This yields a maximum brightness of 12.8 mag in May 2016. The coma was rather diffuse (DC 2-3), measuring less than 1'.
--------------------
Comet 144P/Kushida (P=7.57a) will appear in the morning sky at the beginning of September 2016. Until the start of December it will move from Cancer towards Virgo, thereby fading. According to the ICQ brightness parameters (m0=8.5 mag / n=8) it will be of magnitude 13. However, in 2008/09 the post-perihelion brightness parameters were derived as m0=6.0m/n=8. Thus the comet would be 2.0-2.5 mag brighter.
Only 35 observations could be used to analyse this apparition. The brightness evolution can be rather well described by the formula m = 7.2 mag + 5×log D + 17.5×log r, yielding a peak brightness of 11.5 mag at the start of September 2016. During the apparition the coma diameter shrunk continuously from 1.8' (160.000 km) to 0.7' (60.000 km). The coma was rather diffuse with the degree of condensation decreasing from DC 3 to DC 2. One international observer reported coma diameters of about 8' (700.000 km) and a maximum brightness of 9.0 mag. Comparing these values with previous apparitions, these estimates are rather unplausible. Applying the brightness parameters of the apparition 2008/09 to the current apparition yield a maximum brightness of 11.0 mag. The maximum coma diameter in 2008/09 measured 325.000 km.
Total Brightness and Coma Diameter
--------------------
Observations of comet 174P/Echeclus (P=34.99a) – then positioned in the constellation Pisces – showed a rapid brightening at the end of August 2016. At Aug. 27.745 UT it was of magnitude 17.8 mag, brightening to 15.2 mag until Aug. 28.686 UT. During the following days this brightness remained constant. On Aug. 30 a faint coma of diameter 14" could be recognized, which was displaced by 1-2" towards South (CBET 4313).
--------------------
One magnitude fainter than expected was comet 315P/LONEOS (P=11.23a) during winter 2016/17. It reached magnitude 14.0 at perihelion at the start of February 2017. The diameter of the medium-condensed (DC 4) coma reached 0.6'. The brightness parameters are in the order m0=9.0 mag/n=4.
--------------------
Few observations of comet 333P/LINEAR (P=8.68a) have been published. These indicate a brightness evolution, which can be rather well represented by the parameters m0=11.5 mag / n=4. In early March 2016 the reported brightness was about 11.5-12.0 mag, in early April about 13.5 mag, with a coma diameter short of 1'.
Andreas Kammerer
