NGC 4993: Targeting a mysterious galaxy

Fermi Gamma-ray Space Telescope

Gamma rays can only be observed from space as (thankfully) they can't penetrate the Earth's atmosphere. NASA's Fermi telescope performs allsky surveys in order to find phenomena such as gamma ray bursts. It found one in the same area of the sky as NGC 4993, which could be related to the potential gravitational wave event. It took more than one telescope to uncover the collision

between two neutron stars

Atacama Large Millimeter/submillimeter Array (ALMA)

ALMA is an array of radio telescopes in Chile that combines the signal of 66 telescopes in order to create a really sharp radio image. The observations of NGC 4993 that ALMA performed in August were following up the gamma ray burst in order to see how it behaved at different wavelengths.

Hubble Space

Telescope

The Hubble Space Telescope observed NGC 4993 in both optical and infrared wavelengths. An automated Twitter account

tweeted that Hubble was observing a binary neutron star merger, but the tweet was later removed. Public records still show that the observations were made as a follow-up for a potential

gravitational detection.

Chandra X-ray telescope

Astronomical X-rays also need to be observed above the Earth's atmosphere,

and NASA's Chandra X-ray observatory was also part of the follow-up programme observing the gamma ray burst. The 'overwrite' programme that pointed the telescope towards the GRB was specifically looking for GRBs that could be

related to gravitational waves.

Very Large Telescope (VLT)

One of the eight-metre telescopes that comprises the VLT at the European Southern Observatory used its spectrograph, known as XSHOOTER, to observe the galaxy in visible and infrared wavelengths. The observing programme was performing follow-up observations of potential gravitational wave sources.