Alert Notice 574: Monitoring of EPIC 204278916 requested

April 25, 2017: Dr. Carlo Manara (ESA Science and Technology SCI-S, the Netherlands) and colleagues have requested AAVSO assistance in monitoring the young, disk-bearing low-mass (M type) pre-main-sequence star EPIC 204278916 (2MASS J16020757-2257467).

Dr. Manara reports that this star showed "a very interesting dimming event in August-September 2014 which may be caused by transiting material (exo-comets like), as we discussed in [our paper] (Scaringi et al., 2016MNRAS.463.2265S, It would be very useful to know whether this event has any periodicity in order to constrain the possible scenario...The major dimming [up to 65%] we see is ~1.2 mag in V, others are ~0.5-0.8 mag" in V. He also notes that "the dimming event we saw lasted for some ~25 days, although the most extreme event was ~1 day long. Based on the noisy WASP data we have [there are] some suggestions that the event happens every ~100 days, but we are not sure about it."

Dr. Manara requests ongoing monitoring of this system to look for additional dimming events and to observe any that are seen, so that he and his colleagues may determine if periodicity exists in these events and to study its nature. Beginning now and continuing until further notice, nightly observations - one to a few observations per night - in V are requested. Weekly observations in B are also requested. If a dimming event occurs, observations in V and B at a higher cadence are requested. Unfiltered [CV] observations "may also be valuable simply to see whether the star will dim again." Visual observations are welcome.

EPIC 204278916 is R = 13.90, V = 14.8, and B = 15.7.

Coordinates (2000.0) for EPIC 204278916:  R.A. 16 02 07.58  Dec. -22 57 46.9  

Charts: Charts with a comparison star sequence for EPIC 204278916 may be created using the AAVSO Variable Star Plotter (VSP).

Submit observations: Please submit observations to the AAVSO International Database using the name
EPIC 204278916.

This campaign is being monitored on the AAVSO Observing Campaigns webpage and is being followed on the Campaigns and Observation Reports Forum at


This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.


Information on submitting observations to the AAVSO may be found at:


An Alert Notice archive is available at the following URL:

Subscribing and Unsubscribing may be done at the following URL:


A Special Notice archive is available at the following URL:

Subscribing and Unsubscribing may be done at the following URL:


Please support the AAVSO and its mission -- Join or donate today: