Spectrum of comet 46P Wirtanen on Dec 15, 2018


Optical image
  (white box represents slit position for spectrum imaging)

Date & Time: Dec 15 2018, 24:04 JST(+0900), 1min. exposed
Optical: Meade 25cm(10") Schmidt Cassegrain with a conversion lens(f=1250mm, F5.0)
Auto-guided with Meade LX200 Equatorial & Pictor 201 XT
Cooled CCD Camera: SBIG ST-402ME (Cooling Temp.: -25°C)
Location: Ooizumi, Hokuto city, Yamanashi pref.


Spectrogram & Intensity distribution

Date & Time: Dec 15 2018, from 24:01 to 24:04 JST(+0900), 3min. exposed
Optical: Meade 25cm(10") Schmidt Cassegrain (f=2500mm, F10.0)
with SBIG DSS7 spectrometer (slit width: 0.05mm)
Auto-guided with Meade LX200 Equatorial & Pictor 201 XT
Cooled CCD Camera: SBIG ST-402ME (Cooling Temp.: -25°C)
Location: Ooizumi, Hokuto city, Yamanashi pref.


This page has displayed the optical image of comet Wirtanen on Dec 15, 2018 and its spectrogram taken with an amateur-oriented spectrometer.
Same as other many comets, coma of the comet has emission bands of carbon molecular (C2) called the "swan band" in visible band. It is known that the bands are the gathering of many lines resolved with the high-performance spectrometer. We can take greenish-colored comet photographs due to an intensive swan band around 5100Å. It is considered that the C2 molecular has been generated from the acetylene molecular (C2H2), which was firstly recognized in a spectrogram of the comet Hyakutake (C/1996B2) in 1996, with the photodissociation process as follows.
C2H2 ⇒ C2H + H ⇒ C2 + H + H
Moreover, the spectrogram shows you lines of the cyan (CN), the radical of ammonia (NH2), and so on.
I can show you more good-conditioned other comet's spectrograms indicated below.
C/2013UC10Comet Catalina (Jan 9, 2016)
C/2014Q2 Comet Lovejoy (Dec 29, 2014)
C/2013R1 Comet Lovejoy (Dec 1, 2013)
C/2009P1Comet Garradd (Jan 29, 2012)


46P Wirtanen on Dec 29, 2018
46P Wirtanen on Dec 14 & 15, 2018

Copyright(c) 2018 by Naoyuki Kurita, All rights reserved.
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