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=== [[Example:Varuna|Optical lightcurve of (20000) Varuna]] === | === [[Example:Varuna|Optical lightcurve of (20000) Varuna]] === | ||
This example demonstrates a data reduction process in which the optical lightcurve of the fastly rotating trans-Neptunian object (TNO), (20000) Varuna has been measured.
In this example we demonstrate how the tasks in the FITSH package can be exploited to create a color composite astronomical image from individual scientific frames. In principle, a nice colorful image requires low noise, so either we need long exposure frames or multiple images should be combined in order to obtain this sufficiently low noise level. Since both the guiding errors of the telescope mounts and the presence of the atmospheric refraction impede us from longer exposure times, we focus on now methods based on multiple image combination. Additionally, this method also has the advantage that small but explicit dithering in the telescope position allows us to reject bad pixels or flat errors from the final image by taking a median average of the individual frames.
Here we demonstrate how the astrometry of a target object can be done using the tasks of the FITSH package. This example relates to the example shown above, regarding to the optical photometry of Varuna.
In this example, we demonstrate how the FITSH task can be used to completely reduce a data series acquired for a transit of the extrasolar planet HAT-P-13b. These observations were made on the night of 2010 December 27/28, between 23:21 and 04:28 UT using the [ccdsh.konkoly.hu/wiki/Schmidt_telescope 60/90/180 cm Schmidt telescope] located on the Piszkés-tető Mountain Station of the Konkoly Observatory, Hungary. The nominal length of the transit of this planet is approximately 3.5 hours, and this series of observations were almost scheduled for the predicted mid-transit time, 01:49 UT (using the available ephemerides at that time). All in all, 460 individual frames were taken with a net exposure time of 20 seconds, thus one cycle was approximately 42 seconds (i.e. adding the 22 seconds of overhead yielded by the camera readout). See the paper Transit timing variations in the HAT-P-13 planetary system for more details about the physics of this planetary system (and where these measurements have been published shortly after this observation).