New stage of eclipsing episode of V651 Mon?

(vsnet-alert 642)

V651 Mon, the binary central star of NGC 2346 currently showing a deep eclipsing episode second time in the history, seems to entering a new stage of the evolution of eclipses. Since Dec. 1, no available observations have shown this star below mag 14, in contrast to deep eclipses reported in November. The cloud in front of the binary getting transparent or homogeneous again?

    YYMMDD(UT)   mag    code
    961108.141   139:   POY
    961109.095   136    JEN
    961109.735  <138    Wnt
    961110.139  <131    POY
    961113.667  12.29V  Kis
    961114.250   134    KIN
    961114.610   130    Wnt
    961114.823  12.47V  Oud
    961115.694   123    Wnt
    961116.640   121    Wnt
    961116.699  12.00V  Oud
    961119.747  12.41V  Oud
    961121.089   146:   POY
    961122.672  <136    Wnt
    961129.715  <139    Wnt
    961130.619  <135    Ths
    961130.705  <139    Wnt
    961201.812   136    Wnt
    961202.062   131    POY
    961202.822   131    Wnt
    961203.747   127    Wnt
    961204.000   120    KSL
    961205.067   124    POY
    961206.765   126    Wnt
    961207.597   136    Wnt
    961209.589  12.88   Oud
    961211.607  12.58   Oud
    961213.966   132    DIE
    961214.660  12.88   Oud
    961215.631   139    Ths
    961219.331   130    SQN

   (compiled from vsnet-obs reports)

Despite intereference by the moon, observers are strongly urged to monitor this star for the coming week when the next 16-day-period eclipse is expected.

Taichi Kato

CCD image on Dec. 9

A CCD image taken on Dec. 9, when a deep eclipse was expected, clearly shows the star.

Costero's comment

(vsnet-alert 648)

This message is to give you my opinion of what is going on with V651 Mon. I believe this second cloud is smaller and/or closer to the binary than the first one that caused the variations in 1984-1985, presumably due to occultations (a more appropriate word than eclipses, as suggested by R.H. Mendez in the 7th Latin-American Regional Meeting of the IAU in 1992) by a dust-reach cloud in front of the binary orbit. It apparently is passing one side of the orbit projected on the sky, and entering the other side, hence producing two occultations in two different phases. If so, the first minimum will decrease (as observed). and the second will increase and then also decrease in the months to come.

Hope this will encourage the fallow-up observations by VSNET enthusiastic members, whose work is impressively valuable and useful. I wish you and all those related to VSNET a Marry Christmas and a very fruitful 1997. I also hope to be able to join you all very soon in the fallow-up of this and other exciting objects.

Most sincerely,

Rafael Costero
Instituto de Astronomia, UNAM

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