Transit Search
Method
The Transit method of detection relies on the edge-on
alignment of the extrasolar system. If a planetary system is oriented so that
Earth lies near the plane of the planet's orbit, then once per orbit the
planet passes between its star and the Earth, causing a transit. This
orientation is more likely for planets orbiting close to their parent star.
During a transit, the planet blocks some of the light from the star, causing
the star to appear dimmer (see figure below). For Jupiter-sized planets
transiting Sun-sized stars, the expected dimming of the star's light will be
about 1%, and the duration of the transit should be a few hours.
Move mouse over figure to view
animated transit (300 K continuous loop GIF, requires JavaScript to
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Figure based on one by Hans Deeg, from
'Transits
of Extrasolar Planets'
To look for such a
transit, the my sytem takes timed exposures of the same field-of-view
all night for as many nights as the field is favorably positioned (usually
around 2 months) for thousands of stars in the field. Other software is run to
analyze the processed data for variable stars and transit candidates. It takes
two or more transits (or cycles in a variable star) to discern the period of
the orbit (or the variability).
The Transit method therefore favors
giant planets orbiting sun-like stars in close orbits. The results of
successful radial-velocity planetary searches have shown that planetary
systems of this type could be quite common.When an observing campaign is completed for a particular field,
the multitude of data are run through software which, after correcting for
many sources of distortion and noise, to see some of the sample,
please click here- :
Khalid's Instrument
The main instrument used
in the my project was a 50mm focal length, f/1.2 lens coupled to SBIG CCD camera, imaging an approximately 40 degree square patch of sky.
The CCD size is 735 x 510 to obtain images with a scale of 37 arcseconds per pixel over a
field of view 5.25 x 7.57 degrees.
The telescope/camera system is mounted on a Meade LX200 equatorial
fork mount . This SCT with a nominal
focal length of 2000 mm which is motor-driven to track the apparent motion of the heavens.
The camera is from Santa Barbara Instruments Group CCD which build
in with
autoguider. It tracks a guide star and
compensates for errors in the telescope drive and mounting.
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The Khalid's telescope. Click on image for a
larger view and identification of the telescope's main parts.
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