---
author:
- 'Y. Moulane$^\dagger$, E. Jehin, P. Rousselot, J. Manfroid, Y. Shinnaka, F. J. Pozuelos, D. Hutsemékers, C. Opitom, B. Yang,'
- 'Z. Benkhaldoun'
bibliography:
- 'Moulane\_21P.bib'
date: 'Received/accepted'
title: 'Photometry and high-resolution spectroscopy of comet 21P/Giacobini-Zinner during its 2018 apparition [^1]'
---

Introduction {#intro}
============

Comet 21P/Giacobini-Zinner (hereafter 21P) is a JF with a short period of 6.5 years. 21P was discovered in 1900 by Michel Giacobini and rediscovered by Ernst Zinner in 1913[^2]. After its discovery, 21P was observed in most of its apparitions and many photometric and spectroscopic measurements were reported. In September 1985, 21P was the first comet visited by the International Cometary Exporer (ICE) spacecraft to study the interaction between the solar wind and the cometary atmosphere [@Von1986; @Scarf1986]. 21P is also known as the parent body of the Draconids meteor shower [@Beech1986; @Egal2019]. Many spectroscopic-photometric studies at various wavelength ranges have been performed since its discovery [@Schleicher1987; @Cochran1987; @Fink1996; @Weaver1999; @Lara2003; @Combi2011] including production rates measurements, atomic and molecular abundances. 21P is the prototype of depleted comets in C$_2$ and C$_3$ with respect to CN and to OH [@Schleicher1987; @AHearn1995]. C$_2$ and C$_3$ relative abundances are about 5 and 10 times smaller than 