This week’s image from the Hubble Space Telescope is striking: the beautiful galaxy NCG 1097, as captured by two of Hubble’s instruments working together. Located 48 million light-years away in the constellation Fornax, this barred spiral galaxy has a twisted shape caused by gravitational interactions with a nearby companion galaxy called NCG 1097A.
This particular galaxy is known for being the site of no fewer than three supernovae in the past two decades, with stars exploding in epic events as they reached the end of their lives. The supernovae were named SN 1992bd, SN 1999eu, and SN 2003B, after the years of their observations.
The heart of NGC 1097, a barred spiral galaxy about 48 million light-years from Earth in the constellation Fornax. ESA/Hubble & NASA, D. Sand, K. Sheth
This image of NGC 1097 was taken with two of Hubble’s instruments, the Wide Field Camera 3 (WFC3) and the Advanced Camera for Surveys (ACS). To create this one image, both instruments were used to observe the same target, then data from both was combined to create the image.
“The idea that two different cameras can take one image is not very intuitive,” Hubble scientists explain. “However, it makes much more sense when you delve into how beautiful astronomical images like this are put together. Our eyes can detect light waves with optical wavelengths between about 380 and 750 nanometers, using three types of receptors, each of which is sensitive to only a fraction of that range. Our brains interpret these specific wavelengths as colors. In contrast, a telescope camera such as the WFC3 or ACS is sensitive to a single, wide range of wavelengths to maximize the amount of light collected. Raw images from telescopes are always in shades of gray and show only the amount of light that is collected across all those wavelengths.”
Both the WFC3 and the ACS were used to image specific wavelengths in the galaxy, as checked using filters. Each filter is used to look at a specific wavelength that corresponds to a particular color and produces a grayscale image. Then a total of seven of these filtered images were combined to produce the image as seen above.