A statistical analysis of the accuracy of the digitized magnitudes of photometric plates on the time scale of decades with an application to the century-long light curve of KIC 8462852

Abstract

We present a statistical analysis of the accuracy of the digitized magnitudes of photometric plates on the time scale of decades. In our examination of archival Johnson B photometry from the Harvard DASCH archive, we find a median RMS scatter of lightcurves of order 0.15mag over the range B~9-17 for all calibrations. Slight underlying systematics (trends or flux discontinuities) are on a level of ~<=0.2mag per century (1889-1990) for the majority of constant stars. These historic data can be unambiguously used for processes that happen on scales of magnitudes, and need to be carefully examined in cases approaching the noise floor. The characterization of these limits in photometric stability may guide future studies in their use of plate archives. We explain these limitations for the example case of KIC8462852, which has been claimed to dim by 0.16mag per century, and show that this trend cannot be considered as significant.

ApJ accepted

References in corpus (7)

• The Second-Generation Guide Star Catalog: Description and Properties
• Planet Hunters X. KIC 8462852 - Where's the Flux?
• The Ĝ Search for Extraterrestrial Civilizations with Large Energy Supplies. IV. The Signatures and Information Content of Transiting Megastructures
• KIC 8462852 - The Infrared Flux
• IRTF/SPEX Observations of the Unusual Kepler Lightcurve System KIC8462852
• An ultrahigh-speed digitizer for the Harvard College Observatory astronomical plates
• Var C: Long-term photometric and spectral variability of an LBV in M33

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• Modelling the KIC8462852 light curves: compatibility of the dips and secular dimming with an exocomet interpretation
• KIC 8462852: Will the Trojans return in 2021?
• Extinction and the Dimming of KIC 8462852
• Mysterious eclipses in the light-curve of KIC8462852: a possible explanation
• Detection of a repeated transit signature in the light curve of the enigma star KIC 8462852: a 928-day period?
• Sonneberg plate photometry for Boyajian's Star in two passbands
• Where Is the Flux Going? The Long-Term Photometric Variability of Boyajian's Star
• The KIC 8462852 Light Curve From 2015.75 to 2018.18 Shows a Variable Secular Decline
• Archives of Photographic PLates for Astronomical USE (APPLAUSE) Digitisation of astronomical plates and their integration into the International Virtual Observatory
• The GALEX View of "Boyajian's Star" (KIC 8462852)
• Analysis of a Century's Worth of AR Scorpii Photometry from DASCH and ASAS-SN
• The year-long flux variations in Boyajian's star are asymmetric or aperiodic
• Extrasolar enigmas: from disintegrating exoplanets to exoasteroids