Visibility II / V
I photographed the Iwamoto comet again a couple of weeks back. The comet had clearly dimmed since the previous sighting . The stacked images still show a dim tail, but the individual images no longer contain any information about it.
The main image of the observation is the median stack of images taken in a couple of hours. Because the comet moves relative to the stars and the images are aligned according to the comet, the median stack removes the stars from the image moderately efficiently. The following image is an average stack of the same still images. The third image is a single minute-long exposure of a comet.