Compass and Scale Image for Comet ISON
At the time of the Hubble observations on April 30, 2013, the comet was 3.9 astronomical units (363 million miles) from the Sun. The comet was 4.32 astronomical units (402 million miles) from Earth.
The image was created from Hubble data from proposal 13229 by the Hubble Heritage Team, PI: Z. Levay, M. Mutchler, C. Christian, L. Frattare, W. Januszewski, M. Livio, J. Mack, and J. Sokol (STScI/AURA), and K. Noll (NASA/GSFC). High-level science products for these data are available from the MAST archive.
F606W (V) and F814W (I)
This image is a composite of separate exposures acquired by the WFC3/UVIS instrument. Several filters were used to sample various wavelengths. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are:
Grayscale: F606W (V) (of comet)
Cyan/blue: F606W (V)
Red/orange: F814W (I)