Alert Notice 636: SDSS J141118.31+481257.6 rebrightening - photometry requested

June 1, 2018: Further to AAVSO Alert Notice 635, the AMCVn binary SDSS J141118.31+481257.6 is rebrightening, and the expected superoutburst may be underway.

Dr. Thomas Kupfer (University of California, Santa Barbara) requests continued monitoring and high-cadence observations. He writes: "As predicted the object started to brighten again. Last night [May 31/Jun 1] we found it at 16mag and quickly rising with ZTF. I expect that it will now go into a superoutburst phase where it stays very bright for a few weeks. During that phase we are expected to see superhumps in the accretion disc which show a period which is slightly different than the orbital period (46min for this system) and are powerful to learn about the mass ratio and accretion discs in general."

Observers are requested to monitor this object closely until at least ten days after it has returned to minimum. Filtered observations are preferred, but all observations are welcome. Re the cadence of observations, Dr. Kupfer continues: "I think the best would be continuous observations, perhaps keep exposure times short (below one minute). But I would say even with a cadence of 2-3min we should be able to resolve the superhumps."

The most recent observations in the AAVSO International Database show SDSS J141118.31+481257.6 on 2018 Jun. 01.37179-01.38044-01.38907 UT at V magnitude 16.448-15.738-16.493 (J.-F. Gout, Scottsdale, AZ).

Coordinates (2000.0):  R.A. 14 11 18.32   Decl. +48 12 57.5

Charts: Charts with a comparison star sequence for SDSS J141118.31+481257.6 may be created using the AAVSO Variable Star Plotter (VSP).

Submit observations: Please submit observations to the AAVSO International Database using the name SDSS J141118.31+481257.6.

This campaign is being followed in the AAVSO Time Sensitive Alerts Forum at


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

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