NGC1097 is a barred spiral galaxy in the Fornax constellation in the Southern skies and is approximately 48 million light-years away.

During September and October 2023, I started imaging NGC1097 late in my imaging sessions, after the altitude of my initial target had dropped below 45 degrees. Unfortunately, the very high humidity in the early Spring mornings had made the seeing absolutely awful and all the images were unusable. It was only after completing the imaging in mid December 2023 that I became aware of supernova SN2023rve that had started in this galaxy on 8th September 2023. Fortunately, I don't delete bad images and so I was able to analyse the progress of the supernova. Using the Dynamic PSF routine of PixInsight, I was able to measure the flux of the supernova and calibrate it against a nearby magnitude 13.5 star (estimated as 2,700 light-years away by inverting its parallax in the latest GAIA database). 

A small video of the luminance channel of my images is shown in Revision E (click on the thumbnail image titled "E" under the Revisions heading on the RHS column above). My imaging started three days after the supernova was reported (but unknown to me at the time) and continued until day 92. On the right hand side of the video frames I have included a plot of the supernova flux relative to the reference star in each of the imaging filters that I used. The peak of the flux was sometime between day 3 and day 16. Over time, the blue channel flux has diminished much more rapidly than the red channel, so the region is cooling quite quickly. Unfortunately,  on day three I only took luminance images.

The flux of SN2023rve (near its peak) was approximately equal to the 13.5 mag reference star. Given that flux diminishes as a square of the distance and that the distances of the objects are known, the supernova was (48,000,000/2700)^2 = 316 million times brighter than the reference star. Very bright indeed, and why we wouldn't want a supernova explosion anywhere near us in our galaxy!

Another interesting feature of this galaxy is the two (three?) tidal streams (regions of stars and/or gases emanating from a galaxy). While faintly visible in the main image, I have highlighted them in a highly stretched and inverted image below. Tidal stream A is very unusual as it has a dog-leg shape and is discussed in the paper (https://ar5iv.labs.arxiv.org/html/1006.1353)  which analysed spectroscopic measurements from the 8.2m VLT (Very Large Telescope) in Chile. Tidal stream B also seems to emanate from the very bright core of this galaxy and there appears to be an extremely faint extension to this stream (marked C) on the other side of the galaxy. More imaging time is required to a ascertain if this is real or an artifact of processing, noise or my imagination!



Of course, the other interesting feature of NGC1097 is the recent (in astronomical terms) collision with another galaxy. The core of the colliding galaxy (NGC1097a) is clearly visible at the bottom, and the disruption to the spiral arm in the bottom left quadrant of this galaxy is quite dramatic.

This was the first broadband image I have taken with my new monochrome camera, so there was a steep learning curve processing this image. It was made all-the-more difficult by the extremely bright core of the galaxy.

I hope you've enjoy exploring NGC1097!