SIMBAD references

Result. of an international campaign to photometrically monitor the unique pre-main-sequence eclipsing object KH 15D are reported. An updated ephemeris for the eclipse is derived that incorporates a slightly revised period of 48.36 days. There is some evidence that the orbital period is actually twice that value, with two eclipses occurring per cycle. The extraordinary depth (∼3.5 mag) and duration (∼18 days) of the eclipse indicate that it is caused by circumstellar matter, presumably the inner portion of a disk. The eclipse has continued to lengthen with time, and the central brightness reversals are not as extreme as they once were. V-R and V-I colors indicate that the system is slightly bluer near minimum light. Ingress and egress are remarkably well modeled by the passage of a knife edge across a limb-darkened star. Possible models for the system are briefly discussed.