SN2022hrs is a type 1A supernova in NGC4647 discovered on16th April 2022 by Koichi Itagaki.

The image is a compilation of 36 shots of SN2022hrs collected over a 4 month interval from April 19th to August 20th. An effort was made to collect data on every clear night during this period, ending only when the host galaxy dipped too low in the evening sky. NGC4647 is the smaller galaxy to the lower left; M60 is the neighbouring and much brighter galaxy at the upper right. The supernova is indicated by the short yellow line.

Apart from the first image collected on April 19th when heavy cloud cover necessitated using 20 sec subs and only 5 mins total integration time was possible, generally 15-30 mins of data were gathered each night as 1 min subs. Individual images collected each night were stacked using DSS. The same program was then used to rotate and align each of the nightly stacked images.

Final image processing was performed using the data analysis program Matlab. The sky background and brightness level of the core of M60 were measured and used to set a consistent brightness display scale. Significant variations in sky and object brightness were observed, particularly on the nights of May 14 and June 9 when a nearly full moon was located nearby. Automating the processing this way ensured a fairly consistent display treatment, allowing variations in the brightness of the supernova to be better seen.

Quantitative measurements of the supernova luminosity were made by integrating the pixel count within a circle spanning about 15" and subtracting background estimated on the perimeter of this region. Similar measurements were made for 20 stars in the immediate vicinity and reported Gaia magnitudes (ranging from 12.5 to 16.5) were used to establish a luminosity relationship. The estimated uncertainty ranges from about 0.05-0.10 magnitudes. The calculated magnitude of SN2022hrs is plotted as a function of date.