J/A+A/574/A38 TRAPPIST monitoring of comet C/2012 F6 (Lemmon) (Opitom+, 2015)
TRAPPIST monitoring of comet C/2012 F6 (Lemmon).
Opitom C., Jehin E., Manfroid J., Hutsemekers D., Gillon M., Magain P.
<Astron. Astrophys. 574, A38 (2015)>
=2015A&A...574A..38O 2015A&A...574A..38O
ADC_Keywords: Comets ; Spectroscopy
Keywords: comets: individual: C/2012 F6 (Lemmon) - techniques: photometric
Abstract:
We report the results of the long-term narrowband photometry and
imaging monitoring of comet C/2012 F6 (Lemmon) with the robotic
TRAPPIST telescope (La Silla observatory). Observations covered 52
nights pre- and post-perihelion between December 11, 2012 and June 11,
2013. We followed the evolution of the OH, NH, CN, C3 and C2
production rates computed with the Haser model as well as the
evolution of the A(θ)fρ parameter as a proxy for the
dust production. All five gas species display similar slopes for the
heliocentric dependence. An asymmetry about perihelion is observed,
the rate of brightening being steeper than the rate of fading. The
chemical composition of the comet's coma is changing slightly along
the orbit: the relative abundance of C2 to CN is decreasing for
heliocentric distances larger than 1.4AU while the C3 to CN ratio
is constant during our observations. The behavior of the dust is
different from that of the gas, the slope of the heliocentric
dependence becoming steeper in early February, correlated to a change
of the visual lightcurve slope. However, the dust color does not vary
during the observations. The application of several enhancement
techniques on the images revealed structures in the CN, C3 and C2
images. These features imply the existence of one or several active
zone(s) on the comet nucleus. The shape of the structures is similar
in those three filters and changes from a roughly hourglass shape in
December and January to a corkscrew shape in February and March. The
structures in the continuum filters (sampling the dust) are not
correlated to those observed for the gas. During several full nights
in February, we observed changes in the CN and C2 structures repeating
periodically due to the nucleus rotation, our derived rotational
period being of 9.52±0.05 hours.
Description:
Observational circumstances, OH, NH, CN, C_3 and C_2 production rates
and A(θ)fρ values of comet C/2012 F6 (Lemmon) obtained
using the TRAPPIST telescope
Comet osculator elements:
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Code Name Elem q e i H1
d AU deg mag
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C/2012 F6 Lemmon 2456375.5 0.7312462 0.9985127 82.607958 7.65
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
obslog.dat 87 52 Observational circumstances of comet C/2012 F6
(Lemmon) (table2)
q.dat 113 46 OH, NH, CN, C3 and C2 production rates of
comet C/2012 F6(Lemmon) obtained using the
TRAPPIST telescope (table4)
afrho.dat 73 46 A(α)fρ values of comet C/2012 F6
(Lemmon) obtained using the TRAPPIST telescope
(table6)
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Byte-by-byte Description of file: obslog.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Date Start date of the observations (UT)
(YYYY MMM DD.dd)
15 A1 --- --- [-]
16- 20 F5.2 --- End End day of the observation
22- 26 F5.2 AU r [-2/1.7] Heliocentric Distance
28- 31 F4.2 AU Delta [0.99/2] Geocentric distance Δ
33- 37 F5.1 km/s HV [-25/25] Heliocentric Velocity
39- 42 F4.1 deg PhA [29/58] Phase Angle
44- 48 F5.1 deg PA [149/300] Position Angle
50- 51 I2 --- OH [1/12]? Number of observations in the OH filter
53- 54 I2 --- NH [1/13]? Number of observations in the NH filter
56- 57 I2 --- CN [1/25]? Number of observations in the CN filter
59- 60 I2 --- C3 [1/13]? Number of observations in the C3 filter
62- 63 I2 --- C2 [1/12]? Number of observations in the C2 filter
65- 66 I2 --- UC [1/12]? Number of observations in the UC filter
68- 69 I2 --- BC [1/12]? Number of observations in the BC filter
71- 72 I2 --- GC [1/12]? Number of observations in the GC filter
74- 75 I2 --- RC [1/12]? Number of observations in the RC filter
77- 78 I2 --- B [1/14]? Number of observations in the B filter
80- 81 I2 --- V [1/14]? Number of observations in the V filter
83- 84 I2 --- R [1/14]? Number of observations in the R filter
86- 87 I2 --- I [1/14]? Number of observations in the I filter
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Byte-by-byte Description of file: q.dat
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Bytes Format Units Label Explanations
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1- 11 A11 "date" Date Date of the observations
13- 17 F5.2 AU r [-2/1.7] Heliocentric Distance
19- 25 E7.3 s-1 Q(OH) ? OH production rate (molecules/s)
27- 33 E7.3 s-1 e_Q(OH) ? rms uncertainty on Q(OH)
35- 41 E7.3 s-1 Q(H2O) ? H2O production rate (molecules/s)
43- 49 E7.3 s-1 e_Q(H2O) ? rms uncertainty on Q(H2O)
51- 57 E7.3 s-1 Q(NH) ? NH production rate (molecules/s)
59- 65 E7.3 s-1 e_Q(NH) ? rms uncertainty on Q(NH)
67- 73 E7.3 s-1 Q(CN) ? CN production rate (molecules/s)
75- 81 E7.3 s-1 e_Q(CN) ? rms uncertainty on Q(CN)
83- 89 E7.3 s-1 Q(C3) ? C3 production rate (molecules/s)
91- 97 E7.3 s-1 e_Q(C3) ? rms uncertainty on Q(C3)
99-105 E7.3 s-1 Q(C2) ? C2 production rate (molecules/s)
107-113 E7.3 s-1 e_Q(C2) ? rms uncertainty on Q(C2)
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Byte-by-byte Description of file: afrho.dat
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Bytes Format Units Label Explanations
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1- 11 A11 "date" Date Date of the observations (UT) (YYYY MMM DD)
13- 17 F5.2 AU r [-2/1.7] Heliocentric Distance
19- 24 E6.3 cm UC ? A(α)fρ from UC filter
26- 31 E6.3 cm e_UC ? rms uncertainty on UC
33- 38 E6.3 cm BC ? A(α)fρ from BC filter
40- 45 E6.3 cm e_BC ? rms uncertainty on BC
47- 52 E6.3 cm GC ? A(α)fρ from GC filter
54- 59 E6.3 cm e_GC ? rms uncertainty on GC
61- 66 E6.3 cm RC ? A(α)fρ from RC filter
68- 73 E6.3 cm e_RC ? rms uncertainty on RC
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Acknowledgements:
Cyrielle Opitom, cyrielle.opitom(at)ulg.ac.be
(End) Cyrielle Opitom [ULg, Belgium], Patricia Vannier [CDS] 10-Oct-2014