The concurrent realization of large aperture, wide-field telescopes; sensitive, large pixel-count detector arrays; and high-speed data networks/computing systems has ushered in what is sometimes regarded as the epoch of "time-domain" astronomy, wherein large portions of the sky are sampled several times per night to identify erupting, flaring, rotating, or orbiting sources that are not distinguishable in traditional "staring" modes of observing. Several large-scale surveys are either in progress or in various stages of development, the most ambitious of which is the Large Synoptic Survey Telescope (LSST), which uses an 8.4-m special-purpose telescope that will produce 30 terabytes of data per night and discover more than a quarter-million supernova per year. Many more objects of yet unknown character are likely to be found.
The many science objectives of these enormous time-domain surveys will be fully realized only through rapid and efficient follow-up by what must be an array of support telescopes. Fortunately, characterization as to the type of transient source and redshift often requires only low-resolution optical/near-IR spectroscopy and therefore modest aperture if the telescopes are equipped with high-throughput instrumentation. An important step in this direction is the "SED Machine" being planned by post-doctoral fellow Nicholas Konidaris at the California Institute of Technology (Pasadena). The instrument is basically a low-resolution prism-dispersed spectrograph equipped with highly transmissive coatings and an integral field unit to access a broad central region of the image. Initial design estimates put the throughput of the spectrograph on a par with the highest achieved for any astronomical spectrograph in the world.
Dr. Konidaris has assembled a talented and ambitious team of young astronomers and students who will build the first of these systems for the Mt. Palomar 60-inch Oschin Schmidt telescope and who plan to address objects now being found through the Palomar Transient Factory (PTF) project. The team will be overseen by Caltech faculty, and includes an exciting element of outreach through the targeted participation of under-represented undergraduate students in the area. Moreover, the SED Machine is intended to serve as a prototype for copies that could be constructed at a fraction of the parts cost of the original, the first copy being intended for the National Central University, Institute of Astronomy, Taiwan.
Funding for development and construction of the prototype spectrograph is being provided by NSF's Division of Astronomical Sciences through its Advanced Technologies and Instrumentation program.
In the past decade astronomers have made tremendous technological progress in fielding wide field of view telescope, enormous solid-state imagers with enormous pixel counts, and sophisticated data reduction pipelines that push these pixels through supercomputers, in order to find astronomical "events". These events might by flares on nearby stars, accretion of hydrogen from one star onto its companion (nova), an asteroid streaking by earth, an exploding star (supernovae), gamma ray bursts, or one of many other phenomena. The realization of all of these technologies has ushered in the era of time-domain astronomy. Astronomers who focus on the time domain have been clever about using telescopes of apertures from a few centimeters to 8 meters in order to discover these astronomical events. The main limiting factor to progress is the lack of spectroscopic capabilities for classifying these events. SED Machine was born out of the need for low-cost spectroscopic classification. As part of this NSF award, Dr. Konidaris (PI) and his team designed a powerful new spectrograph combining a wide-field acquisition camera (designed by student then graduate student Dr. Ben-Ami), high-throughput low-resolution (R~100) wide field (30") spectrograph for the Palomar 60-inch telescope. This instrument was delivered to the telescope in June 2013 (23 months after receiving NSF funding). The instrument is now awaiting a final data reduction pipeline in order to classify astronomical events within few minutes of discovery. The project has also trained a number of individuals in the art of designing, managing, constructing, integrating, and commissioning new instruments. The two postdocs running SED Machine now have permanent positions in astronomy. The senior graduate student who was heavily involved in the instrument is now a prize fellow at Harvard. A mix of five more graduate, undergraduate, and high-school students were involved in various aspects of the instrument.
