CG Dra: a VSS campaign

[Maxim Usatov]

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

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[Jeremy Shears]

Never a dull moment with this CV, Max!

[Maxim Usatov]

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

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[Maxim Usatov]

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

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   Figure_1.png
   

[Maxim Usatov]

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

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   Figure_1-1.png
   

[Maxim Usatov]

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

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[Maxim Usatov]

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

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[Maxim Usatov]

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 2 months, 1 week ago by Maxim Usatov.

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[Jeremy Shears]

Fingers crossed for good weather for the upcoming bright outburst Max

[Jeremy Shears]

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

[Maxim Usatov]

Thanks, Jeremy.

Eclipses No(s): 108
State: Fading

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

Max

• This reply was modified 2 months, 1 week ago by Maxim Usatov.

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[Maxim Usatov]

We’re just past the bright outburst. Data continues to flow from A1, I’m submitting to the BAA database. (It would be nice to automate submission somehow – an API would be great!)

Max

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