British Astronomical Association
Supporting amateur astronomers since 1890

Secondary menu

Main menu

BAA Community Member Pages Hugh Allen
Image search

Comet 46P/Wirtanen spectrum

Image

Expand image

About this observation
Observer
Hugh Allen
Time of observation
13/12/2018 - 21:00
Object
Comet 46P/Wirtanen
Observing location
Oakhill Somerset
Equipment
8" Meade LX90 at f6.3
Alpy 600 spectroscope
Atik 314L camera
BASS software
Tags
Like This Image
Share

Spectrum of Comet 46P/Wirtanen in a clear(ish) sky on Thursday night. I would not describe the comet as particularly bright even in a telescope, its 5th magnitude being spread over a large surface. My unguided set-up struggled to pull much signal from above the noise even by keeping the bright nucleus on or near the slit. So for presentation I ran the final 1D spectrum through a weak Gaussian filter to smooth some of the noise and make the stronger features more visible. I also manually 'snipped' the sky background out of the spectrum rather than subtract the sky background which would have introduced even more noise (I snipped light pollution lines at 5461Å [mercury], 5577Å [oxygen airglow], and 5893Å [sodium]). Nevertheless, the 'classic' cometary emission lines are clearly visible: Swan emission bands from C₂ radicals, C₃ radicals, and an intense near-UV emission from CN radicals. Even NH₂ radicals can be identified. The spectrum is response corrected using the (then) nearby B9V star Xi Tau. All in all I found this a more difficult target than I expected.

Comments

nickjames's picture

Great to see spectroscopists having a go at this comet. It is a challenge but the results are really good.

Copyright of all images and other observations submitted to the BAA remains with the owner of the work. Reproduction of the work by third-parties is expressly forbidden without the consent of the copyright holder. For more information, please contact the webmaster.