Example Lightcurves

The images above show the entire output of the photometry pipeline using the eclipsing binary RY Cancri as an example. This lightcurve contains 1042 measurements of brightness obtained over 104 years. The plot uses the GSC2.3.2 designation N2312220105 for this variable. The star's magnitude (brightness) is plotted against time (first panel) and chronological plate sequence (second panel). The third panel shows in black the spatial bin of the image from bin 1 at the center to bin 9 at the edge; and in red the number of local calibrators to determine the image's local correction of irregular spatial variations in plate sensitivity. The fourth panel is used to verify that the star's variability does not come from image saturation effects. The fifth panel shows the local calibration error. Finally, the sixth panel shows the difference between magnitudes with (black) and without (red) local calibration. A description of plotting symbols appears on the database page.

lc_n2312220105_all

We have the option of removing all but the good points as shown by the lightcurve on the left. Note the faint points below the rest, which correspond to eclipses of the primary star by its fainter companion.

lc_n2312220105_good

Here is the lightcurve of RY Cancri folded at its known binary period of 1.092943 days, to show the eclipse. The light-curve is plotted over two cycles, the first cycle shows estimated error bars for each point.

lc_n2312220105_fold.

For quality control purposes we are also interested in stars that do NOT vary. Such constant-brightness stars enable sensitive determination of various systematic effects and provide a completely independent measure of uncertainties. At left is the lightcurve of such a star demonstrating about +/-0.1mag photometry over 600 plates, that span 100 years and 19 different plate-series.

lc_n2313320277