CG Dra: a VSS campaign

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Viewing 20 posts - 141 through 160 (of 191 total)
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  • #612205
    Jeremy Shears
    Participant

    Looks like normal service has been resumed, Max! 👍🏻

    #612206
    Maxim Usatov
    Participant

    Alas, not yet. Even sunny Spain has weather.

    Attachments:
    #612208
    Gianni
    Participant

    Interesting and great set of observations, for which I envy you. I have always wanted to observe and construct a light curve, at least on an educational level. Instead, from my town, L’Aquila a small town in the mountains of central Italy, the stars have disappeared. Sloppy lighting, headlights pointed everywhere and air pollution have erased them from the sky. Even in the mountains, the gleam reaches halfway up the sky. When I was a boy, 8-10 stars of the Pleiades could be seen with the naked eye.

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    #612210
    Maxim Usatov
    Participant

    Gianni, it is getting more and more difficult indeed. Where I live (Bortle 8-9) I can barely see anything at all, yet still visual astronomy is possible with a night vision device. Even through a small refractor it is possible to see Markarian’s chain, M1 and other wonders via IR-filtered view, so not everything is lost. I don’t think I would manage to collect these 20K+ observations had not the telescope been fully automated. Building “robotic” observatory was really the key for me, so the telescope might as well be somewhere else under the dark and steady skies, as I don’t touch the hardware at this point. The romance of having hands-on hardware experience is lost, but this allowed me focus on data pipelines, processing and, also, trying to understand the physical nature of the star, which is more intriguing than messing with the hardware for me. I think if you’re really after building light curves then accessing a remote observatory is a plus.

    Max

    #612220
    Gianni
    Participant

    Yes, real Astronomy is done with stars. Maxim, holy words what you say. It’s just that I am a self builder and I have to put into practice what I do. I’ve also thought about building a small instrument to be operated remotely, but that’s too big an undertaking for me. More seriously, I have fallen back on observing the colours of the sky at sunrise and sunset. I have been practising these observations for three years and from them I can detect the state of transparency of the atmosphere and the ozone in the stratosphere.

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    #612221
    Maxim Usatov
    Participant

    Gianni, it would be interesting to read more about your atmosphere project. If sky pollution is an issue then a lot of projects are to be done in the solar system, including automating observations of the solar photosphere and chromosphere, nightly monitoring of the planets and the Moon, and so on. Lots of inspiration in the BAA Journal.

    Eclipses No(s): 86
    State: Outburst

    V/L/S-type eclipse (V-shaped, low or none orbital hump, symmetric), expected for the outburst. I find this state to be the most interesting, as almost every light curve is unique. Very good data quality with check star sigma ~ 0.016 mag, revealing the flickering dynamics. Interesting “fading” wave after the egress.

    Max

    Attachments:
    #612229
    Maxim Usatov
    Participant

    Eclipses No(s): 87
    State: Fading

    Surprising curve today on the way down – broad U-shaped profile, highly asymmetric, no orbital hump. Very extended post-egress brightening all the way from phase ~ 1.15 to 1.50 – almost as if the bright spot is on the wrong side of the eclipse. Assuming this can be called a post-egress hump, except that it is a very broad one, this curve can probably be classified as U/L/PEH. We have seen this profile during the fade on June 30th except that back then the PEH was much narrower.

    What causes such variation of minima shapes – this “U” is extremely broad – bright and very extended accretion disk?

    Wild speculation, again, on the magnetic theme. Can CG Dra’s WD magnetic field switch on and off, sometimes turning the system to something resembling a polar? The patchy stream of material can block the bright spot at phase ~ 0.8, resulting in lower ingress flux, compared to egress. This U/L/PEH curve is somewhat similar to HU Aqr and SDSS J093537.46+161950.8 which Hardy et al. (2017) describe as a “typical polar.”

    Seeing overall was very good tonight – there are interesting flickering oscillations towards the end of the curve. Note some fast flickering episodes reach close to 0.2 mag in amplitude.

    Max

    Attachments:
    #612232
    Gianni
    Participant

    Maxim, I made an initial note of my study in ‘Astronomia UAI’ magazine of the ‘Unione Astrofili Italiani’. However, it is written in Italian, if you want to give me an @ I’ll send it to you.

    #612261
    Maxim Usatov
    Participant

    Gianni, I am afraid I will be unable to understand Italian – but looking forward to an article in English. 🙂

    Eclipses No(s): 88, 89
    State: Fading

    Two U/L/PEH + U/L/PEH eclipses. Accretion disk fading in brightness. There are two short post-egress brightenings of the same profile on both eclipses, peaking at exactly phase 1.14, so this is likely a PEH feature and not a flickering artifact. This is easily seen on the phase plot as post-egress magnitudes are a little different and one PEH appears to be on the top of another one. The bright spot appears to be compact or partially obscured by something, as it is not a smooth hump.

    Max

    Attachments:
    #612288
    Maxim Usatov
    Participant

    Eclipses No(s): 90
    State: Fading
    U/L/S eclipse, PEH has disappeared.

    • This reply was modified 2 months, 4 weeks ago by Maxim Usatov.
    Attachments:
    #612311
    Jeremy Shears
    Participant

    Thanks Max. A very petite eclipse!

    #612486
    Maxim Usatov
    Participant

    Unfortunately, the weather has been really horrible all these days… Managed to get a few data points here and there, but not enough to build a curve, so I haven’t been posting. Tonight the clouds have interrupted the session only early in the morning – so good data.

    Eclipses No(s): 91
    State: Rising
    Typical accretion disk-dominated U/L/S eclipse. We need a new period/epoch analysis, as the old one appears to be inaccurate.

    Max

    #612490
    Jeremy Shears
    Participant

    Good to hear the clouds have finally parted, Max.

    #612491
    Eric Watkins
    Participant

    Max, very nice work indeed. The advantage of having a good overseas site is obvious. May try and give it a go if we get a spell of good seeing as the nights get longer. Keep up the good work

    #612492
    Maxim Usatov
    Participant

    Thank you, Eric!

    #612553
    Maxim Usatov
    Participant

    In outburst, ~ 0.15 mag flickering.

    Attachments:
    #612760
    Maxim Usatov
    Participant

    After a 2-week pause caused by a patch of bad weather, loss of power supply and Internet connectivity at the observatory – all at the same time…

    Eclipses No(s): 92
    State: Rising
    Appears to be U/L/S eclipse, similar to the previous one (#91), just skewed due to rising magnitude. Old epoch is far off the minima, needs revisiting.

    Max

    Attachments:
    #612762
    Jeremy Shears
    Participant

    Good to see you back in action Max. Sounds like you’ve had a rough patch.

    #612789
    Maxim Usatov
    Participant

    Thanks, Jeremy. Glad to be back.

    Eclipses No(s): 93
    State: Bright Outburst?

    It looks like CG Dra is rising into bright outburst mode – this is the brightest it’s been since the last bright outburst. A pattern could be emerging with the last outburst of the cycle being fainter than the previous one before bright outburst – but too early to tell.

    Given that this should be an accretion disk (AD) dominated state where no bright spot should be promiment, a bright feature at phases 0.75-0.90, I think, can be interpreted as the re-emergence of the AD from the preceding fade that peaked at phase 0.75 – perhaps, due to the obscuration of a bright inner AD region by the stream overflow. The geometry should be compatible. Within this interpretation, this eclipse is V/L/S-type – V-shaped, no orbital hump, symmetric.

    Max

    Attachments:
    #612796
    Jeremy Shears
    Participant

    Definitely worth pursuing your lead about outburst amplitude relative to previous and successive brighter outbursts, Max. Correlations were found by Frank Bateson regarding normal outbursts between superoutbursts in the UGSU system, VW Hyi.

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