comet observations and comet spectrum during night 17/18 july

Some comets are observed especially C/2017 S3 (PANSTARRS) and 21P/GZ, also some other comets are observed during this night with sometimes clouds that coming in and must stopped the observations for some time.  comets that could be observed are:  21P/GZ, 29PSW-1, 37/FORBES, C/2017 M4, C/2017 S3, C2018 C2. also i tried to make a spectrum of comet C/2017 S3 with a C11 + L200 spectrograph with 150 l/mm grating. This was my fiorst attempt to make a spectrum of such a faint and fuzzy object (core magnitude about 12.3). I added my FR 0.63 for catching more light.  It was difficult to find this comet in the guidingcamera of the spectroscope, because very faint and very low in altitude, also i must wait until the comet was above the tree between the comet and my observatory.  I started with 1200 sec. exposuretime for each image. I took 3 images (total exposure=1 hour). I could see some good signal but not the best.  After processing is saw some weird behaviour and not exactly very sharp spectrum.  I think the FR isn’t a good idea end best should be removed. It is not a good ideae to get ‘glass’ in the lightpath for spectroscopy…

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