I had taken a few shots of an interesting galaxy on August 2019. Its reference is NGC6951. This galaxy has a nice pair of curved arms and I considered it a good target.
Unfortunately, I was unable to take the time to complete the required number of images during last summer and I decided to wait till 2020.
May 2020. I decided to continue with the images of this galaxy and I was catching a few more shots of it when I realized that a new star appeared on the images.
Supernovae on NGC6952 Galaxy
Credit: Antonio Peña
http://www.rochesterastronomy.org/supernova.html, This is the reference website which registers all the supernovae discovered during the year. I searched for NGC6951 and no entry was on the page!
Today, it is very difficult to discover a SN. There is a lot of well-trained amateurs searching the sky during the night and even more… there is a lot of automatic telescopes surveying the sky looking for new stars (supernovae) on galaxies.
I checked a few of my images and the suspect star was on the same position what leaded to discard an asteroid.
After some investigation, I discovered that NGC6951 is also catalogued as NGC6952. An anomaly on the New General Catalogue of Nebulae and Clusters of Stars.
I checked this reference on the 2020 SN list and it was listed as discovered on Febrery 2020 by Patrick Wiggins! Mistery solved.
This is the way to discover a supernovae; you have to have an old image of a remote galaxy and then you have to take a new image to check if some new star is on the field around the galaxy. This is the method used by amateur astronomers and this is the algorithm carried out by the automatic surveys to find these dying stars.