After observations suggesting the presence of fragments in the inner coma of C/2019 Y4 ATLAS, we imaged this comet every night. In particular, tonight we observed at least three fragments, telling that the comet really experienced a breakup event. Here it is in our image.
The image above comes from the average of 63, 60-seconds exposures, remotely taken with the “Elena” robotic unit (PlaneWave 17″+Paramount ME+SBIG STL-6303E) available at Virtual Telescope in Rome. The telescope tracked the apparent motion of the comet and images were stacked using the orbit of the comet, to provide the best accuracy. Image scale is 0.63″/pixel. No image processing was performed, to preserve the reliability of the visible features. The signal-to-noise ratio is quite good, so it is possible to do, carefully, some image processing.
In the upper left insert, you can see the central region, this time after applying an unsharp masking filtering: there are at least four fragments there, telling us the comet broke up for sure, this causing the evident fading trend of the object.
Below, our previously released image, made using a subset of available images:
In the upper left insert, we present a 2x re-scaled detail, processed via unsharp masking. In short: the same situation as in the first image, which is of course better, using more sub-frames: consider it as your reference image.
We have much more data from all the past nights and we are processing them, to provide a detailed analysis, but we wanted to share right away this latest, amazing view of comet C/2019 Y4 ATLAS.
Bottom line: As seen by Gianluca Masi at the Virtual Telescope Project in Rome on April 11, 2020, the nucleus of comet C/2019 Y4 ATLAS has broken into three or four fragments. Vlad Dumitrescu in Romania also captured the comet this weekend; he saw three fragments.