Group of observers with the goal of spectroscopic observations in the Rhine-Main-Area established

by Gerrit Grutzeck

Comparison of an ESO VLT based spectrum (ADP.2017-10-25T20:19:10.630) with the spectrum obtained with LHires III using the example of α Bootes in the wavelength range of the Hα line.

During summer of 2016, discussions between members of the Astronomy Club of AWO Mörfelden revealed an interest in spectroscopy.

This way, a team of representatives from vari- ous institutions has been formed: Hajo Zitzkowski, Gerd Köllner und Dr. Georg Piehler. At a later stage Dominik Plonka and Dr. Jürgen Kozok joined the team.

Based to this mixed team, we see ourselves as a regional working group. We are primarily focused on spectroscopy. Like all who had chosen the path of spectroscopy, we also had to deal with the main parts of the theory as well as the speciality of the practical work, further with the special aspects reduc- ing the data. Due to the fact that we did not own a spectro- graph to start, we borrowed and tested various devices from other organizations to gain practical experience.

Our special thanks to Dr. Lothar Schanne as representative of the spectroscopy group of the VdS for providing a slitless MINISPEC and to the Volkssternwarte Regensburg providing a DADOS with 200 and 900 lines/mm grids in- cluding a Lumicon QHY8 camera. Further thanks go to the Astronomie Stiftung Trebur. This foundation has two prism spectrographs which we used for collecting first experiences. As these devices still had to be optimized, we were able to learn a lot about observational practice.

Meanwhile we bought a CCD camera (ATIK 383L mono) and one team member bought a LHires III from Shelyak. This enables us now to obtain usable observations. For first observational attempts we had the chance to use the "Friesenheimer Lichteimer" (20-inch Newton, f=2030 mm with Barlowlense extended to 5000 mm) of the Selztal Observatory.

In the following part we want to present a first spectrum of α-Bootes taken in the Hα area, which was obtained with this device (Fig. 1). We used a 15 μm slit, 2400 lines/mm grating and 60 sec exposure time with the ATIK 383L mono camera (Bin=2) at JD=2458618.39806. The ESO spectrum for comparison was taken from the ESO Archive Science Portal. It shows the relative flux, normalized to the continuum. By means of a sliding average we have reduced the enormous resolution (R = 107200) to a comparable measure for the LHires III.

It was important for us to see that we could obtain a result not in contradiction with data from other - professional – sources using the LHires III. The next step will be evaluating the limiting magnitude, we are able to obtain spectra at dif- ferent resolutions in a reasonable quality. We believe that we are now at a stage to contribute with quality observations. Therefore, we are open regarding possible cooperation or suggestions to contribute to existing campaigns.


Figure: ESO VLT spectrum, ESO Archive Science Portal, File: ADP.2017-10-25T20:19:10.630

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