CG Dra: a VSS campaign

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  • #610453
    Jeremy Shears
    Participant

    Impressively tight data, Max!

    #610455
    Maxim Usatov
    Participant

    Thanks, Jeremy!

    Today’s data – really interesting. Note the eclipse profile is asymmetric with what appears to be a gentler egress on the first event. The second dip is ~ 0.1898 d from the first one, so looks like I was lucky and that is the second eclipse this night, also with a gentle egress. Could be something going on with the accretion disk?

    Seeing conditions improved later into the night, with better precision on the second eclipse. Periodic interruptions in the light curve are refocusing events at 30-minute intervals. The telescope decided it wants to autofocus near both minima. I’ll increase the period to 60 minutes to minimize this effect.

    If I combine this data with the previous night’s run (with polynomial fit to remove the trend) I get 0.189617 +/- 0.07808 d period reported using the ANOVA algorithm, which appears to be in good agreement with the 0.1893 +/- 0.0006 d period used by Bruch et al. (1997).

    All the data is in AAVSO and BAAVSS databases.

    Max

    • This reply was modified 1 month, 1 week ago by Maxim Usatov.
    Attachments:
    #610459
    Jeremy Shears
    Participant

    Super – many thanks Max. All very interesting indeed.

    #610526
    Maxim Usatov
    Participant

    Today’s data. If this is an eclipse, what would explain that it didn’t fully recover until about 3.6 hours later?

    Max

    Attachments:
    #610537
    Jeremy Shears
    Participant

    Not sure Max. Does the main dip coincide with the time when an eclipse should have occurred?

    #610540
    Maxim Usatov
    Participant

    Yes, all three coincide except that the minima of the first one visually appears to have occurred earlier than calculated:

    5/23/2022 22:45:13 2459723.44807 59722.9480699999 OBSERVED (EARLY)
    5/24/2022 03:16:52 2459723.63671 59723.1367100002 OBSERVED
    5/26/2022 00:33:17 2459725.52311 59725.02311 OBSERVED

    I have estimated ToM using Peranso and numbers from Shears et al. (2008).

    Max

    #610543
    Maxim Usatov
    Participant

    Data from today, at quiescence. Noisy data, as we approach 17th mag, and the seeing wasn’t perfect. Looks like we see another pair of eclipses with an asymmetric profile. Looking at various literature breaking down DN light curves, I think this curve can be explained with a low-inclination grazing eclipse and a hot spot responsible for the ingress hump. Things going through my head:

    1) If CG Dra has developed a hot spot and switched to asymmetric profile, how typical this state switching is for dwarf novae?
    2) Is there any user-friendly light curve modeling software so we could try to build a model of the system to fit this data?

    Max

    Attachments:
    #610552
    Maxim Usatov
    Participant

    Data from today, at quiescence. High-quality measurement, also asymmetric profile with gentler egress. Looks like a hot spot. Later into the night a single 0.2 mag brightening point – is this something like a flare? I am going to take a break until June 4th, hopefully to continue monitoring CG Dra on return.

    Max

    • This reply was modified 1 month, 1 week ago by Maxim Usatov.
    Attachments:
    #610555
    Maxim Usatov
    Participant

    AoV fitting.

    Attachments:
    #610563
    Maxim Usatov
    Participant

    Squeezed one more run before the break.

    Attachments:
    #610565
    Jeremy Shears
    Participant

    Great stuff – thanks Max

    #610912
    Maxim Usatov
    Participant

    Back to monitoring. Severe turbulence at the beginning of the session as the telescope was still cooling down, but I thought I’d remain this in the dataset as it appears to capture the ingress hump (hot spot?) I think that it’s another eclipse near the end of the session in the morning when SNR began to decrease. Period precision keeps improving.

    Max

    • This reply was modified 4 weeks, 1 day ago by Maxim Usatov.
    #610916
    Jeremy Shears
    Participant

    Thanks Max. Good to see you back!

    #610922
    Maxim Usatov
    Participant

    Thanks, Jeremy!

    Attachments:
    #610962
    Maxim Usatov
    Participant

    Today’s data. CG Dra on the rise. The gap in data during the eclipse coincides with the GEM meridian flip. Eclipse also partially visible at the beginning of the session. Pretty stable atmosphere tonight with 0.025 sigma on the check star despite all the heat – could barely cool the sensor down to -20C at midnight. Hot spot (?) hump visible prior the eclipse, along with the gentle egress.

    It is interesting also to observe how nights are different “photometrically” as the processing pipeline is fixed. I think this is the most tight data of all so far.

    Max

    • This reply was modified 3 weeks, 4 days ago by Maxim Usatov.
    Attachments:
    #610968
    Jeremy Shears
    Participant

    Those data really are incredibly tight, Max!

    #611000
    Maxim Usatov
    Participant

    Another good night. Outburst appears to be leveling off at a fainter magnitude. Ingress hump not as pronounced.

    • This reply was modified 3 weeks, 3 days ago by Maxim Usatov.
    Attachments:
    #611005
    Maxim Usatov
    Participant

    Fading. Not very good sky conditions.

    Attachments:
    #611027
    Maxim Usatov
    Participant

    Clouds tonight. Not sure if data of this quality should be submitted to AAVSO/BAA VSS – please advise.

    Attachments:
    #611039
    Jeremy Shears
    Participant

    No problem submitting, Max. Researchers can subsequently apply any data quality selection criteria they wish. Without any data they have no choice. The other consideration is that your data, at the very least, provide a snapshot of the system status at that time.

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