A. Boattini discovered a comet in images taken in the course of the Catalina Sky Survey on Nov. 4, 2013 near the border of the constellations Lepus and Eridanus. Comet C/2013 V1 (Boattini) showed a significantly condensed 20" coma of magnitude 15.5 and a curved, 1.2' tail in p.a. 230°. It will pass perihelion at the end of April 2014, expected to reach 14 mag (CBET 3689 / MPEC 2013-W01). It should be brighter than 15.5 mag until mid-July. During this interval it will pass the constellations Eridanus, Cetus, Aries, Perseus, Camelopardalis and Ursa Major, being well situated in the evening sky. The published observations can be best represented by the parameters m0=10.8 mag / n=2.5, indicating a maximum brightness of 13.7 mag. The diameter of the rather diffuse (DC 3) coma was in the order of 1'. Images showed a significantly curved dust tail of rather high surface brightness – surprisingly, regarding the rather large solar distance.
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On Feb. 14, 2014 images taken with the Near Earth Object Wide-field Infrared Survey Explorer (NEOWISE, formerly the WISE satellite) showed a new comet in the constellation Libra. Comet C/2014 C3 (NEOWISE) showed a 15x17" coma of total magnitude 17.5 and a 53" tail, which spanned p.a. 313 to 200°. It passed perihelion on its 1200 years object in mid-January and will now fade slowly (CBET 3810 / MPEC 2014-G81). Visual observers reported a magnitude of 15.0 (2 mag brighter than expected) and a coma diameter of 0.4' in March 2014.
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On June 7, 2014 the NEOWISE team discovered a comet in the constellation Aquarius. Follow-up observations of comet P/2014 L2 (NEOWISE) in mid-June showed a significantly condensed 25" coma of magnitude 15.5 mag and a 1.5' tail in p.a. 255°. The comet rounds the Sun on a 15.9 years orbit and reached perihelion in mid-July 2014 (CBET 3901 / MPEC 2014-R69). Its opposition loop will be positioned near the border of the constellations Aquarius/Pisces with the comet expected to reach 15.0 mag in August/September. According to the few published observations the comet reached 13.5-14.0 mag at the end of August 2014, with the significantly condensed (DC 6) coma measuring 1'.
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During late summer and fall 2014 owners of larger instruments should try to observe comet 4P/Faye (P=7.51a) in the morning sky. The comet passed perihelion already in May, but was then positioned very near the Sun. It should be still as bright as 13-14 mag. It moves from Gemini to the border of Cancer/Hydra. The comet was rarely observed between fall 2014 and spring 2015. It showed a constant magnitude of 14.5 mag between fall 2014 and January 2015, displaying a weakly condensed coma of 0.7' diameter. The subsequent fading was surprisingly slow with the comet still of magnitude 15.0 at the start of April.
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At the beginning of June 2014 photographers and visual observers could glimpse comet 17P/Holmes (P=6.89a). Alan Hale estimated it to be of magnitude 12.5 to 13.1 during the first week of June, with the diffuse (DC 2-3) coma measuring slightly more than 1'. The comet could be observed by amateurs during the following summer months. The estimates indicate a slow fading from 13.0 mag at the end of June to 14.0 mag at the end of August. It showed a medium-condensed (DC 3-4) coma of diameter about 1-1.5'. On Jan. 26, 2015 the comet experienced a further outburst. Whereas the red magnitude was 18.0 mag during the days before it had increased to 14.5 mag on Jan. 26. Visual observations during the following days yielded a maximum of 13.0 mag. Until mid-February 2015 the comet had faded to 14.5 mag.
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With larger instruments comet 32P/Comas Sola (P=9.58a) could be glimpsed, starting in mid-August 2014. Until March 2015 it will move from Gemini into eastern Leo, expected to reach 14.0 mag at the end of the year 2014. Based on 70 observations the brightness evolution can be approximately described by the formula m = 11.3 mag + 5×log D + 5×log r, however with rather large uncertainties due to the too small variance in solar distance. The brightness peaked at magnitude 13.7 at the opening of February 2015. According to the estimates between the start of the apparition and the end of 2014 the coma diameter decreased from 0.8' (85.000 km) to 0.6' (45.000 km), but increased thereafter, reaching 1.2' (70.000 km) in mid-March 2015. The degree of condensation was constant at DC 3 until the end of 2014, thereafter decreasing to DC 1-2 until mid-March 2015. CCD-observers recorded a tail, reaching 10' (2 mio. km), pointing towards WNW.
Total Brightness and Coma Diameter
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Comet 52P/Harrington-Abell (P=7.58a) could be observed by amateurs during the first three months of 2014 (perihelion occurred on Mar. 7). The comet, moving through the constellations Perseus and Auriga, reached a maximum brightness of 14.0 mag at the end of January. Thus it was nearly 3 magnitudes brighter than expected. It was of magnitude 15.5 at the end of March. The significantly condensed (DC 4-5) coma was of diameter 0.5'.
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According to the very few observations I noticed until mid-September 2014 comet 108P/Ciffreo (P=7.23a) seems to evolve as predicted. Thus it should reach a maximum brightness of 14.5 mag in November 2014. During fall it moves from Taurus into Auriga, being well-placed for mid-European observers. According to the small number of published observations this comet peaked at about magnitude 14.5 in mid-November 2014.
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Observers in the Southern hemisphere started to monitor the slow evolution of comet 117P/Helin-Roman-Alu (P=8.29a) in early 2013. It passed perihelion on its slightly elliptical orbit at the end of March 2014. The estimates confirm the well-known large activity parameter, however, it is not possible to derive the brightness parameters properly. In August 2014 the comet peaked at 13.0 mag, was thus about 1 mag brighter than expected. The diameter of the medium-condensed (DC 4) coma was in the order of 0.5'.
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In spring 2014 comet 134P/Kowal-Vavrova (P=15.56a) became much brighter than expected. It passed perihelion at the end of May, being positioned in the southeastern part of Virgo, peaking at 13.1 mag. The 50 estimates which came to my knowledge, hint towards a time-dependent brightness evolution, with slightly different parameters prior (m0=12.0 mag / nt=0.005) and after (m0=12.5 mag / nt=0.005) perihelion. The diameter of the diffuse (DC 3) coma was estimated to be about 1.0'.
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On May 29, 2014 comet 209P/LINEAR (P=5.03a) passed Earth at a distance of only 0.055 AU - only 8 documented comet passages were closer than that. Despite this close distance, a brightness of only 12 to 14 mag was expected, because this comet shows only a hint of activity.
The 60 visual and CCD-observations, which came to my knowledge, indicate an extraordinary brightness evolution, which is best described by the parameters m0=18.5 mag / n=0. Thus the heliocentric magnitude was constant over a period of three months, although the distance sun-comet increased from 0.98 to 1.57 AE. This means that the comet had increase its activity over these three months. It reached a maximum brightness of 12.2 mag on May 29.
Total Brightness and Coma Diameter
The apparent coma diameter showed a short-time maximum of 1.0' (4.000 km) on May 25, only to shrunk immediately thereafter to less than 0.3'. The uncertainty of the estimates after June 10 is unclear. The reported constant apparent coma diameter would imply that the absolute coma diameter increased again (from 1.000 km at the end of May to 6.000 km at the beginning of August). Between May 20 and June 5 the degree of condensation was about DC 7. Between May 15 and 25 a tail could be determined on CCD images, reaching 0.5° (90.000 km).
In mid-May P. Jenniskens predicted a new meteor shower that should originate from this comet. The meteors should be visible on May 24 between 6:03 UT and 8:09 UT, radiating out of the constellation Camelopardalis. Since Earth passed the comet's orbit close to its perihelion, the relative velocity would only be 19.4 km/s. Actually an increased activity was observed on May 24 between 0hUT and 11hUT in the predicted direction using radio reflections, with a maximum between 7h30 UT und 8h00 UT. The velocities were around 21 km/s. Visual observers indicate a maximum ZHR of about 15 (CBET 3886, IMO Webpage). Broadband photometry by Carl Hergenrother between Feb. 10 and March 10 suggests a rotation period of 10.93 or 21.86 hours, with a higher probability for the longer period. The color index as well as the phase-function slope of the nuclear brightness indicate that this comet belongs to the Jupiter family with an albedo of >0.08 and a nucleus diameter between 1.9 km and 4.9 km. The nucleus gets active at a distance of 1.4 AU and ceases activity after perihelion at the same distance (CBET 3869/70). Using narrowband photometry D. Schleicher calculated extremely low production rates on May 19, which may explain why this comet was discovered just 10 years ago. The water production rate indicates an active area of only 0.01 square kilometers (CBET 3881).
Andreas Kammerer
