25/03/2021
Low Resolution Spectrograph – one of our first spectrum taken.
LowSpec Spectrograph – one of our first spectrum taken.
Here we present one of our first spectrum taken with the low resolution Spectrograph LowSpec. Thanks to the free available design with STL Files, publish by P.J. Gerlach (thanks Paul for your great work), I was able to build this spectrograph, printed with 3D printer and assembled according to Paul‘s guidelines and list of components.
The spectrograph fits well to the 12“ Maksutov of the Urania e.V. Observatory Wiesbaden that we have access to. Currently a grating with 300 lines is installed and used for the observations. It is possible to vary the slit starting with 10µ going up to 100µ and even offering higher widths.
Our target 3 CMi, a Be Star of magnitude 2.89m , was observed using the 30µ slit for 360s. As imaging device we use a ATIK 383L+. The reduction of the spectrum was performed using MIDAS (Fig 1). The CCD was operating in binning mode 2x2 resulting in a linear dispersion of 0,32nm/pixel. Achieved spectal resolution is R=800 @ 650nm.
Fig1: spectrum of 3CMi / Beta CMi
Right away you can easily identify the Balmer sequenz up to H8 at 388.9nm and Hα in Emission. The Hα profile seems to show absorption dips on the left and right wing. Luckily we had observed this object last year end of March a view times. The high resolution spectrum taken with the LHiRes III
On Mar 24th shows a similar Profile. (Fig 2.)
Fig 2: H-alpha spectrum of 3 CMi performed with LHiRes III (23µm slit / 2400 lines/mm ), exposure time of 3600s using the „Friesenheimer Lichteimer“ @ Selztal-Observatory (20 Inch Newton) taken at March 24th 2020. Achieved linear dispersion of 0,0134nm/pixel with a resolution of R=10000.