This is the third in a series of posts introducing and providing essential facts about each of the Frontier Fields.
MACS J0717 has been observed by telescopes in many visible and invisible wavelengths of light. It is one of the most massive galaxy clusters known, and it is the largest known gravitational lens1. Of all of the galaxy clusters known and measured, MACS J0717 lenses the largest area of the sky.
The Massive Cluster Survey (MACS) contains a sample of more than 100 galaxy clusters, measured by the ROSAT telescope to be bright in high-energy X-ray light. The goals of the MACS survey are to categorize and better understand distant massive galaxy clusters. J0717 has the highest X-ray temperature in the MACS survey.
Estimated Dates of Observations: September-November 2014 and February-May 2015
The planned dates for Hubble observations of the Frontier Fields include observations approximately six months apart. This is the time it takes for the cameras on Hubble to swap positions so that both visible-light data and infrared-light data can be captured from the galaxy cluster field and the adjacent parallel field, as described in this post.
Galaxy Cluster Redshift: 0.545
Redshift measures the lengthening of a light wave from an object that is moving away from an observer. For example, when a galaxy is traveling away from Earth, its observed wavelength shifts toward the red end of the electromagnetic spectrum. The galaxy cluster’s cosmological redshift refers to a lengthening of a light wave caused by the expansion of the universe. Light waves emitted by a galaxy cluster stretch as they travel through the expanding universe. The greater the redshift, the farther the light has traveled to reach us.
Galaxy Cluster Distance: approximately 5 billion light-years
Galaxy Cluster Field Coordinates (R.A., Dec.): 07:17:34.0, +37:44:49.0
Parallel Field Coordinates (R.A., Dec.): 07:17:17.0, +37:49:47.3
Related Hubble News:
- Frontier Fields: Hubble Goes Deep (science content reading for students & educators)
- NASA’s Great Observatories Begin Deepest Ever Probe of the Universe
Looking for Hubble data used by scientists?
References to science journal articles: