SN2022hrs is a type Ia supernova in the galaxy NGC 4647, about 61 million light-years from us. With a brightness up to magnitude 12.5 it can be captured with even medium focal lengths. Like many other members at Astrobin, I took the opportunity to take a photo of my first supernova. 

The post by Mike, who even managed to record a spectrum of SN2022hrs, inspired me to try it as well.

Like Mike, I used the Star Analyzer SA-100 from RSpec-Astro for this.  I didn't use a filter at all so as not to artificially limit the spectrum. 

On two consecutive nights, I first aligned the telescope without the grating, steered to the galaxy, and focused on the stars. Then I screwed the SA-100 in front of the camera and aligned it on the basis of some test shots so that there was no overlap of the spectrum of the supernova with other stars or their spectra. Finally, I used the EAF by eye to focus the image on the control iPad and programmed the sequence of images.

The next morning, it turned out that the weather forecast had once again been for an alien parallel universe. Instead of a clear sky, there had been massive clouds overnight. Out of over 100 subs, I could therefore only use a handful. 

The next difficulty arose during the processing. Neither PixInsight nor Astro Pixel Processor nor Affinity Photo were able to process the images with the spectra. Therefore I had to overlay, average and stretch all images by hand. The resulting spectrum seems quite satisfactory to me, despite the problems.

The assignment of the absorption bands is not quite simple. Although values are given in the literature, there is often overlapping, because the bands shift in the direction of shorter or longer wavelengths due to the Doppler shift and the bands widen as a result. On top of that, the spectrum of a Type Ia supernova changes over time. In my spectrum I have therefore indicated only those bands, which I could assign quite surely. 

Nevertheless, the spectrum is sufficient to prove that it is a type Ia supernova. This type lacks the bands of hydrogen, but there are distinct bands of silicon. 

What a great hobby, if we can check from our backyard in which way a star exploded 60 million light years away. :-)