Twenty-five years ago in 1990, the average US house cost $123,000, the Dow Jones averaged 2633 and gasoline cost a little more than a dollar-thirty a gallon. Saturn wasn’t just a planet: it was now a newly launched car company from GM, The Simpsons was aired for the first time and the Space Shuttle Discovery placed the Hubble Space Telescope into orbit.
And it was the beginning of a golden age for astronomers: a perfect trifecta of advances in electronic instrumentation, computing power, and engineering were assembling to produce a new generation of telescopes – one that would radically change the way we understood the cosmos and the forces that drive it.
Want Of Light
Before the W. M. Keck Observatory was built, the 200-inch Hale Telescope at Palomar Observatory reigned supreme. It was the largest telescope in the world, but after 50 years, progress in astronomy was flattening out because the instruments needed more photons than the 5-meter mirror could provide.
The biggest hindrance to an explosion of discoveries was a want of light and the telescopes themselves were the problem. Mirrors larger than Palomar’s could not be made and supported at the exacting levels needed for astronomy.
Every night, all over the world, people look up at the sky and wonder about the distant stars. Here in Hawaii we have the privilege of looking up at a very dark sky, but even here with the naked eye we can only see a few thousand stars. This is mainly because of the small size of the lens in our eye, which limits the amount of light it can gather, and also limits the detail we can see for those incredibly distant objects.
This week we will celebrate the 25th anniversary of first light on the Keck I telescope, an event that started the process that has made Hawaii today the best-known place on earth for scientific discovery in astronomy, and the Keck Observatory the home of the two most scientifically productive telescopes on earth.
First light, the first time light from the night sky is focused into an image by a telescope, is a very special event for the community of people required to build and use them, accompanied by a nearly mystical sensation as it culminates years of dedication to completing the project and bringing the Universe a little closer to all humankind.
Since the invention of the telescope 400 years ago, we have been looking at the sky in with much bigger manmade eyes, seeking to learn more and more about our Universe. This has been possible because we have been able to build larger and larger telescopes. For a time telescopes were developed with either lenses or mirrors, but the understanding of telescope design improved, telescopes using mirrors became the choice for larger telescopes. In 1977 the largest telescope on earth was the Hale telescope at Mount Palomar, with a mirror 5 meters in diameter. Astronomers at the University of California knew that their research was reaching the limit of what could be done with the Hale and smaller telescopes, and so they started a project to design and build a 10 meter telescope. This was a very ambitious goal, since even the Hale was known to have limited performance because of the tendency of its mirror to change shape as the telescope was pointed at different places in the sky.
First light is complete… It works very nicely, the images of rich star fields and sweeping nebulae are worth the hours of work it takes to complete the fabrication of a telescope.
The telescope is Makaʻiki, a new 6″ travel scope. Hours of design, cutting and drilling, sanding and spraying paint. There is nothing particularly hard about building a telescope, but it always takes more work that you remember from the last.
As usual the most difficult part of assembly is the last. Installing and aligning the optics. Adjustment of the secondary mirror for the correct position takes an hour of mucking about with allen keys, a Cheshire eyepiece, and a laser collimator. Get it centered, get the tilt right, correct placement of the secondary is critical for good performance of the telescope.
The final step is first light, the traditional ceremony when a new telescope is aimed at the sky for the first time. My traditional first light target is M42, the Great Orion Nebula. An old friend and telescope maker, Bob Goff, often stated he would like to tour this nebula in spirit after he died. I do not know if he made it, but I remember him each time I commission a new telescope and peer at the beauty of this nebula.
Given the time of year I had to get up before dawn for a view of this nebula. Driving uphill from the village I could see Orion rising above the dark shadow of Mauna Kea. In the predawn darkness I set up near Hale Pohaku for my first light checks. Set up is a bit grandiose for this telescope, there is not much to it. Open the tripod, set the scope on top, take the covers off and aim at the sky.
The first object to focus in the telescope was M42, the nebula appearing quite nice at low power. The 40mm eyepiece gives a 3.3° field at about 19x, wide enough to comfortably fit the entire nebula region in the field, from NGC1980 to NGC1981. From there I wandered about the sky… M1, M78, M79, M41, M35 made for a nice sampling of objects.
Higher powers shows that collimation can be a bit touchy in the ‘scope, not a surprise given the single strut design.
There were also three bright planets in the dawn. The brilliant Venus is shining near its maximum brightness right now, showing a nice crescent in the telescope. Mars is still too far away to show much of anything and Jupiter was still quite low in the brightening dawn, the moons barely visible.
First Light complete I knew that the effort to create a new telescope was worth it. Makaʻiki performs as designed. With a sense of satisfaction I headed uphill for breakfast and to join the crew for a day on the summit.
Engineers and astronomers are celebrating the much anticipated first light and first two nights commissioning of the MOSFIRE instrument, now installed on the Keck I telescope at W. M. Keck Observatory. MOSFIRE (Multi-Object Spectrometer For Infra-Red Exploration) will vastly increase the data gathering power of what is already the world’s most productive ground-based observatory.
“This is a near-infrared multi-object spectrograph, similar to our popular LRIS and DEIMOS instruments, only at longer wavelengths,” explained Keck Observatory Observing Support Manager Bob Goodrich. “The dedicated MOSFIRE project team members at Keck Observatory, Caltech, UCLA, and UC Santa Cruz are to be congratulated, as are the dedicated observatory operations staff who worked hard to get MOSFIRE integrated into the Keck I telescope and infrastructure. A lot of people have put in long hours getting ready for this momentous First Light.”
First light with MOSFIRE, and unprocessed image of the interacting galaxies NGC4038 and NGC4039, credit: W. M. Keck Observatory
The first unprocessed image from MOSFIRE was made on the night of April 4, despite thick cirrus clouds over Mauna Kea. The subject was two interacting galaxies known as The Antennae. Additional images adn spectra were gathered on the night of April 5, as part of the continuing commissioning of the instrument.
MOSFIRE gathers spectra, which contain chemical signatures in the light of everything from stars to galaxies, at near-infrared wavelengths (that is, 0.97-2.45 microns, or millionths of a meter). Infrared is light which is beyond red in a rainbow—just beyond what human eyes can detect. Observing in the infrared allows researchers to penetrate cosmic dust clouds and see objects that are otherwise invisible, like the stars circling the supermassive black hole at the center of the Milky Way. It also allows for the study of the most distant objects, the light of which has been stretched beyond the red end of the spectrum by the expansion of the universe.