MicroObservatory is a network of five automated telescopes that can be controlled over the Internet.
The telescopes were developed at the Harvard-Smithsonian Center for Astrophysics and were designed to enable students and teachers nationwide to investigate the wonders of the deep sky from their classrooms. The project is sponsored by the National Science Foundation (RED 9454767), with additional in-kind contributions from Eastman Kodak Company and Apple Computer.
The current locations of the telescopes are shown on a map elsewhere in this Web site. Users of MicroObservatory are responsible for taking their own images by pointing and focusing the telescopes, selecting exposure times, filters, and other parameters. The educational value lies not just in the image returned by the telescope, but in the satisfaction and practical understanding that comes from mastering a powerful scientific tool. Observations can be set up in advance and run automatically.
A nationwide team of educators is helping to test the telescopes and develop additional activities. Users are encouraged to suggest novel applications for the telescopes; suggestions will be credited and posted at this site from time to time. We particularly encourage collaborative projects in which observers share information, images, and data. The creation of a "virtual community" of users is one of the goals of the MicroObservatory project.
Philip Sadler CO-INVESTIGATOR:
Owen Gingerich PROJECT SCIENTIST:
Kenneth Brecher TELESCOPE DESIGN AND PRODUCTION:
Robert Kimberk and Steve Leiker ELECTRONICS & SOFTWARE ENGINEER:
Paul Antonucci SOFTWARE ENGINEER:
Freeman Deutsch PROJECT ENGINEER:
Frank Sienkiewicz and Adam Contos PROJECT MANAGER/
MicroObservatory is designed:|
Technical Description of the MicroObservatory Telescopes
The MicroObservatory telescopes stand about 3 1/2 feet tall and weigh 135 pounds. They separate into a 55 pound base and an 80 pound optical and electronic tube. The two parts travel in separate shipping containers, so that the entire instrument can be moved by two adults. The telescope is driven by stepper motors, slewing 2-3 degrees per second and pointing to an accuracy of typically 3 minutes of arc, once calibrated and modelled by our pointing-correction software.
The MicroObservatory telescopes are an original Maksutov design, with a 6 inch spherical primary mirror and a 5 1/4 inch corrector. There is a 2 inch diagonal mirror which sends the light through a small, low power lens for focussing adjustments, then through a filter wheel with clear, blue (B), yellow-green (V), red (R), infra-red (IR), and neutral density (ND-4) filters. The filter wheel also has an opaque setting that allows for calibration and protection of the charge-coupled device (CCD) light sensor. The overall focal length is 560 mm.
The MicroObservatory also has a finder, which uses a 28 mm focal length Minolta camera lens.
The MicroObservatory Telescopes use Kodak charge-coupled device (CCD) image sensors: the finder camera uses a KAF0400, and the main camera uses a KAF1400. Both are cooled by two-stage thermo-electric coolers, and dark currents are normally quite low.
The KAF0400 is a 768 by 512 sensor with 9 micron by 9 micron pixels, and is used with a Minolta 28mm lens at f/4.5, giving a "plate scale" of 1.1 arc minutes per pixel. To fit on the Mac screens, the images are cropped to 650 wide by 500 pixels high, giving a total field of view of about 12 degrees by 9 degrees for the finder camera. A 30 second exposure typically shows 8th magnitude stars. Normal exposure times are up to 10 minutes, limited by sky fog. Minimum exposure time is .06 seconds. An ND4 filter is provided, and is used with very bright objects or during the day. Exposures of the sun are not permitted without an external solar filter, which must be specially mounted by hand.
The KAF1400 used in the main camera is a 1317 by 1035 sensor with 6.8 micron by 6.8 micron pixels. The 560mm focal length of the main optical system gives a "plate scale" of about 2.5 arc seconds per pixel. This is the "high resolution" mode, with a relatively small field of view. For most normal viewing, the pixels are combined electronically on the CCD into 658 by 517 "binned" pixels of 13.6 microns on a side, each of which is 5 arc seconds high and by 5 arc seconds wide. To fit on the Mac screens, these are cropped to 650 by 500 pixels, giving a field of view of a little less than 1 degree horizontally by just over 2/3 of a degree vertically. A 30 second exposure in the main camera will typically image stars fainter than 15th magnitude. Normal exposures are up to a few minutes, limited by polar alignment and tracking errors as well as sky fog. Minimum exposure is .06 seconds, and an ND4 filter is provided for very bright objects or daytime use. Exposures of the sun are not permitted without an external solar filter, which must be specially mounted by hand.
The telescope is controlled by an Intel 80C196KC microcontroller, and has 16 kbytes of on board RAM and 32 kbytes of ROM. Communications with a Macintosh host computer is via an IEEE 802.3 10 Megabaud link, which runs an ethernet-like protocol.