Reply To: CG Dra: a VSS campaign

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Maxim Usatov

Eclipses No(s): 37
State: Outburst (Peak)

Appears to be another U/L/PEH eclipse – U-shaped, low to none bright spot orbital hump, post-egress hump (PEH). The last one was seen while CG Dra was fading, this one is at the outburst peak. Another option is that it could be a symmetric U/L/S eclipse, but the accretion disk is just getting brighter. (Although this wouldn’t explain why PEH appeared on the June 30th eclipse while CG Dra was fading.)

The PEH appears to appear right after the egress of the accretion disk. I am not sure how to interpret this – asymmetric accretion disk or the appearance of an accretion stream/overflow? I wonder if magnetic forces are in play here.

Looks like flickering originates in the accretion disk or stream, as it is present even during the eclipse. Data quality is pretty good this night, and we can clearly see the flickering magnitude is above the average measurement uncertainty at the bottom of the “U.” There is no standstill on the egress, and this could signify large bright spot reaching the inner portions of the accretion disk. As we suspect CG Dra shows us grazing eclipses this configuration may explain the persistence of flickering throughout the eclipse.


  • This reply was modified 1 month, 1 week ago by Maxim Usatov.