CG Dra: a VSS campaign

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  • #613332
    Maxim Usatov
    Participant

    Eclipses No(s): 101
    State: Outburst

    Just when I thought I’ve seen it all, yet another surprise from CG Dra. The data is noisy, as it’s getting low on the sky, slightly over 30 degrees at midnight, with the Moon visible early in the night and clouds interfering throughout. The profile appears to be U/L/PEH – U-shaped, low orbital hump, post-egress hump (PEH), however, PEH appears to be very wide, lasting about half of cycle. Almost like an anti-phase orbital hump. I don’t remember seeing this profile before. Note, also, a single spike to almost 15.6 magnitude.

    Max

    Attachments:
    #613334
    Jeremy Shears
    Participant

    Never a dull moment with this CV, Max!

    #613390
    Maxim Usatov
    Participant

    Eclipses No(s): 102
    State: Fading

    Appears to be U/H/PEH again, first seen during the fading stage. Prolonged standstill on the egress, potentially signifying a compact bright spot. Assuming this is correct, post-egress hump (PEH) could be explained with an optically think accretion disk, and not an extended bright spot, although we have seen PEHs appearing during outburst stages as well.

    Max

    Attachments:
    #613449
    Maxim Usatov
    Participant

    Eclipses No(s): 103
    State: Quiescent
    U?/N/A.

    Attachments:
    #613499
    Maxim Usatov
    Participant

    Eclipses No(s): 104
    State: Rising
    Accretion disk-dominated U/L/S eclipse profile. Appears to be acceptable quality data even during the Moon up high.
    Max

    Attachments:
    #613516
    Maxim Usatov
    Participant

    Eclipses No(s): 105
    State: Outburst
    U/H/PEH profile – now seen at all stages of CG Dra except the bright outburst stage.
    Max

    Attachments:
    #613609
    Maxim Usatov
    Participant

    Eclipses No(s): 106
    State: Quiescence
    Bad conditions due to clouds, but we can still make out U/N/A-type profile.
    Max

    Attachments:
    #613964
    Maxim Usatov
    Participant

    Eclipses No(s): 107
    State: Outburst or the beginning of a Bright Outburst

    I’m still here, just that the weather doesn’t really help. CG Dra is visible for only a few hours until it sets too low at about midnight. This coming week, I think, is going to be very important, as this dwarf nova will go into its fourth bright outburst since this continuous light curve effort started, and it would be nice to understand if bright outbursts are indeed as periodic as they seem.

    This appears to be a symmetric eclipse, but the orbital hump “iceberg” visible here is of almost 0.2 magnitude amplitude, which is quite odd. In this state CG Dra profile should be accretion disk-dominated, as it’s hot and ionized. As the bright spot supposed to be of constant flux due to the constant mass transfer in the widely accepted outburst model, it shouldn’t appear here at all. I wonder if we are looking at an increased mass transfer episode here, and if so, is this something that triggers bright outbursts?

    Max

    • This reply was modified 5 days, 18 hours ago by Maxim Usatov.
    Attachments:
    #613968
    Jeremy Shears
    Participant

    Fingers crossed for good weather for the upcoming bright outburst Max

    #613975
    Jeremy Shears
    Participant

    Just to add that single point observations of CG Dra are also especially welcome over the next days to constrain the start of the next bright outburst to which Max refers

    #613983
    Maxim Usatov
    Participant

    Thanks, Jeremy.

    Eclipses No(s): 108
    State: Fading

    Looks like E107 was a normal outburst. Bright outburst expected next.

    Max

    • This reply was modified 4 days, 19 hours ago by Maxim Usatov.
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