Astronomers Capture ‘First Light’ with Latest Keck Observatory Imager

The “first-light” image from NIRES is of NGC 7027, a planetary nebula. The NIRES spectrum shows the near-IR spectrum of this nebula dominated by emission lines of hydrogen and helium. The direct image shows NBC 7027 in the K’ filters at 2.2 microns. Photo: W.M. Keck Observatory.

Astronomers at W. M. Keck Observatory successfully captured their first spectral image using the telescope’s newest instrument, the Caltech-built Near-Infrared Echelette Spectrometer (NIRES).

“The Keck Observatory continually strives to provide instrumentation that meets the high aspirations of our scientific community and responds to changing scientific needs,” said Keck Observatory Director Hilton Lewis. “NIRES is expected to be one of the most efficient single-object, near-infrared spectrographs on an eight to ten-meter telescope, designed to study explosive, deep sky phenomena such as supernovae and gamma ray bursts, a capability that is in high demand.”

The first set of commissioning observations using the cutting-edge new instrument included the planetary nebula NGC 7027.

“The power of NIRES is that it can cover a whole spectral range simultaneously with one observation,” said Keith Matthews, the instrument’s principal investigator and a chief instrument scientist at Caltech. “It’s a cross-dispersed spectrograph that works in the infrared from where the visual cuts off out to 2.4 microns where the background from the thermal emission gets severe.”

NIRES arrived at Keck Observatory from Caltech on Apr. 17 and was installed on Keck II on Sept. 28. This long-awaited instrument is perfectly suited for time domain astronomy follow-up observations of targets identified by new surveys that are designed to find transients and exotic objects. Credit: W. M. Keck Observatory.

NIRES will specifically focus on capturing Targets of Opportunity (ToO)—astronomical objects that unexpectedly go ‘boom.’ This capability is part of a groundbreaking new focus in astronomy since the discovery of gravitational waves caused by the collision of two neutron stars in October 2017. Astronomers around the world detected both light and gravitational waves generated by the event, triggering a new era of study known as ‘multi-messenger’ astronomy.

“NIRES will be very useful in this new field of ‘multi-messenger’ astronomy,” said NIRES co-developer Tom Soifer, the Harold Brown Professor of Physics, Emeritus, at Caltech and member of the Keck Observatory Board of Directors. “NIRES does not have to be taken off of the telescope, so it can respond very quickly to transient phenomena. Astronomers can easily turn NIRES to the event and literally use it within a moment’s notice.”

NIRES’ high sensitivity will bring extremely faint objects into focus and hopefully provide clues into what happened in the following the Big Bang. The instrument arrived at Keck Observatory in April 2017 and will be available to Keck Observatory’s science community in February 2018.