Last touched 2001 December 4
Originally published in M-111, the Newsletter of the Richland (Ohio) Astronomical Society
Reflections in the Eyepiece
Amateur Ray Sterner is waiting for his turn to observe with one BIG telescope. And it isn't one of those huge light buckets that you find at summer star parties. You know, the ones with long lines of people waiting for a glimpse of M-13. Instead of a 25-inch, or a 30-inch, Ray is waiting for a glimpse through a 94-inch... a telescope that just happens to be orbiting about 300 miles above the surface of Earth... the Hubble Space Telescope.
And he doesn't want too much... just a peek at a faint galaxy cluster so he can try to get a clearer, deeper picture than that you can get from ground. Indeed, if Sterner's hopes come true, he might be able to show some professional astronomers that a cluster of galaxies isn't what they think it is.
If all goes well, sometime this fall, Sterner will get a couple of hours of time on HST in an effort to image a 19th magnitude cluster of galaxies in Aquarius known as CL2244-02. Ground based images of the cluster show a curious arc of material inside the boundaries of the cluster. Professional astronomers have suggested in journal papers that the arc is the result of the gravity of the cluster bending the light rays of objects behind the cluster. Sterner doesn't think it is anything that fancy.
He just thinks the arc is the result of a collision between two galaxies within the cluster. To help prove his theory, Sterner was awarded time on HST to take a series of images that will hopefully show more detail than ground based ones.
The 38 year old Sterner got his start in amateur astronomy in during the 1960s with a classic instrument - a 2.4-inch refractor. But, that telescope only showed that he was interested enough in the subject to get yet another classic telescope, a Criterion RV-6 - a 6-inch F/8 newtonian on a german equatorial mount. In a matter of time, Sterner got aperture fever and ended up with a equatorially mounted 12.5-inch Cave newtonian.
"I always thought the 6-inch wasn't that good of a scope, until I got my 12-inch. The 12 was too heavy for me to carry outside by myself, so sometimes I could only use the 6-inch. I started using the eyepieces that came with the Cave and discovered that the Criterion eyepiece weren't very good," Sterner said.
Today, Sterner uses a Coulter 13.1-inch, mostly, from his front yard near Woodbine, MD, about 30 miles west of Baltimore. The dobsonian is easier to move around. Both of the old telescopes ended up at one of his schools. He also has a Meade LX-6 that he hopes to do astrophotography or CCD imaging with someday. While work and family doesn't let him do as much observing as he'd like, his front yard, with limiting magnitude of 5.5, often serves as a gathering place for light polluted amateurs from the nearby Washington DC and Baltimore regions.
But, for Sterner there is more to astronomy then just observing. One part of his interest also manifested itself as a once a week reading of scientific literature at his work place, the John Hopkins Applied Physics Laboratory. Another is computers.
In 1974, while in college, Sterner had written a computer program that simulated the effects of colliding galaxies. Like many of the commercial programs available today, his program allowed the compression of millions of years into a few seconds. By experimenting with computer generated galaxies of various sizes and by controlling the angle and speed at which the galaxies passed through or by one another, he could simulate the views we have of many common objects, like M-51.
However, at some point in 1986, Sterner stumbled across a photo of CL2244-02 that appeared as part of an article in the New Scientist. The article was about how it was proposed the arc of material appearing in the cluster was really a gravitationally distorted image - a gravitational lens - of objects behind the galaxy cluster. At about the same time, Sterner was had been reworking his colliding galaxy program so he could create "movies" that graphically display the collisions.
"It sunk in real slow," Sterner said about looking at the image of CL2244-02. He knew he had seen a similar arc-like image, but it was a while before he remembered it was from one of his movies. Running the program on a VAX computer at work, it wasn't long before Sterner was able to recreate something that looked, on the screen, like the photograph.
At this stage, Sterner started to search through the professional journals in interest, to help him prove that the arc wasn't a gravitational lens, but the result of an ancient collision between two galaxies. He used information found in journal articles to fine tune his program to include the colors and ages of the stars that make up the arc. But, he ran into a stumbling block when the stars that make up the arc burned out and died.
Sterner knew the approximate age of the arc from his computer program - that was easy. But, now it became apparent that by the time the arc reached its current size and shape, those stars would have long since used up their nuclear material and gone the way of star dust.
However, more journal searching provided the possible answer. As the arc expanded away from the colliding galaxies, it started to sweep up interstellar gas to form new stars. Next, Sterner added more routines to his program to allow it to simulate the collection of the gas and the formation of new, replacement stars.
So now what to do with his idea? Enter the opportunity for amateur astronomers to win a little bit of time on the Hubble Space Telescope. It was ideal for Sterner, because the photographs he already had for CL2244-02 were taken with some of the largest professional telescopes. To prove his theory, Sterner needs to be able to resolve, in the HST images, details within the arc that his computer generated images predict will be there. If the HST image can show these details, then the burden of proof will fall back to the professional astronomers to show these details could be formed by a gravitational lens.
To do this, he was rewarded about 2.5 hours of time on HST. Sterner will use that to take three 45 minute long exposures through a yellow (V) filter with the wide field/planetary camera. He originally asked for two hours of time, but was allocated 64 minutes. Then, after the flaw in the HST mirror was discovered, he was reallocated more time, but only after his project was reviewed to see if it was still feasible to do with bad mirror. With luck, Sterner hopes to see his project carried out sometime this fall or winter. With the help of specialists at the Space Telescope Science Institute, Sterner will process his images to see what he has.
It may be that the details he needs to see to prove his theory are too faint to see with HST in its current condition - or that the details are not there at all. Sterner is pretty sure that the details are there, but is more worried at the ability of HST to see them.
As part of the deal that enabled him to get the HST time, Sterner will be required to publish an article showing the results. He hopes to publish in the Astrophysical Journal, often considered to be the flagship of the of the professional journals. If his theory is borne out, he then hopes to follow up on it by trying to observe the cluster with other advanced telescopes. The two that he talks about are the Advanced X-ray Astrophysics Facility (AXAF), expected to be launched in 1997, and the Space Infrared Telescope Facility, or SIRTF, planned to be launched at the end of this decade. Sterner has hopes for getting time on these two telescopes because the formation of stars in the arc as it sweeps up the interstellar gas might be observable in the X-ray and infrared wavelengths.
As for amateurs with similar projects in mind, Sterner recommends hard work. "Dig into the professional literature," he said. He also recommended that amateurs pay more attention to the professional journals, even if it is just skimming the abstracts of the journals. "Many amateurs will be surprised that they can understand much of what is talked about in these papers... and they (amateurs) will find them interesting," he said.
Back to Bob's Homepage.