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Alert Notice 532: Observations requested for KIC 8462852

Campaign extended to request ongoing monitoring. This star also the subject of Alert Notice 579 (20170524) and Alert Notice 542 (20160408). - June 2017

October 20, 2015: The AAVSO requests time-series observations of the enigmatic variable object KIC 8462852 beginning immediately and continuing through at least the end of the current observing season. The star is relatively bright (V=11.88) and shows aperiodic dips of a few tenths of a magnitude, the causes of which are unknown. The object is not known to be a close binary or a young stellar object, and there are no other typical indicators of circumstellar material such as infrared emission. More observations are requested to further characterize the star's variability.

Filtered time-series observations in one or more photometric filters are encouraged. Individual fading events have lasted for several days each, but show complex structure on very short timescales. The star itself is also rotating, and shows rotational variation at the millimagnitude level with a period of 0.8797 day. Instrumental observers world-wide are encouraged to participate, and we encourage observers from Asia and the northern Pacific especially to participate to improve temporal coverage of this star.

Coordinates (J2000):  RA 20 06 15.46 , Dec +44 27 24.8

The star is located in Cygnus, which as of today (2015 October 20) is transiting in the early evening. Observations are requested through early 2016 at least while Cygnus is favorably located in the sky. Observers should aim to reach signal to noise values of 50 or higher if possible. Transformed observations made in multiple filters (at least Johnson B and V) may be useful for determining the cause of variability if calibrated colors are obtained. If submitting untransformed data, observers are encouraged to follow this star as part of their long-term observing programs for at least one season; doing so will allow researchers to determine individual photometric offsets and combine data from multiple observers.

A comparison star sequence is available for KIC 8462852, and charts are available via the AAVSO Variable Star Plotter, VSP.

Please promptly report all observations to the AAVSO International Database using the name "KIC 8462852"; please note the space between "KIC" and the identifier which is required for submission.

More information about this object may be found in a recent paper by Boyajian et al. (2015; MNRAS, submitted), available at the following URL:

    http://arxiv.org/abs/1509.03622

This AAVSO Alert Notice was prepared by M. Templeton and E.O. Waagen.

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