Home › Forums › Variable Stars › CG Dra: a VSS campaign
- This topic has 191 replies, 9 voices, and was last updated 1 month, 2 weeks ago by Maxim Usatov.
1 September 2022 at 5:16 pm #612205
Looks like normal service has been resumed, Max! 👍🏻1 September 2022 at 5:27 pm #612206
Alas, not yet. Even sunny Spain has weather.
Attachments:2 September 2022 at 7:51 am #612208
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.
Translated with http://www.DeepL.com/Translator (free version)2 September 2022 at 9:39 am #612210
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.
Max3 September 2022 at 7:17 am #612220
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.
Translated with http://www.DeepL.com/Translator (free version)3 September 2022 at 11:24 am #612221
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
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.
Attachments:4 September 2022 at 12:26 pm #612229
Eclipses No(s): 87
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.
Attachments:4 September 2022 at 3:13 pm #612232
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.5 September 2022 at 12:48 pm #612261
Gianni, I am afraid I will be unable to understand Italian – but looking forward to an article in English. 🙂
Eclipses No(s): 88, 89
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.
Attachments:6 September 2022 at 12:14 pm #612288
Eclipses No(s): 90
U/L/S eclipse, PEH has disappeared.
- This reply was modified 6 months, 2 weeks ago by Maxim Usatov.
Attachments:6 September 2022 at 8:37 pm #612311
Thanks Max. A very petite eclipse!15 September 2022 at 9:55 am #612486
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
Typical accretion disk-dominated U/L/S eclipse. We need a new period/epoch analysis, as the old one appears to be inaccurate.
Attachments:15 September 2022 at 12:17 pm #612490
Good to hear the clouds have finally parted, Max.15 September 2022 at 12:19 pm #612491Eric WatkinsParticipant
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 work15 September 2022 at 2:15 pm #612492
Thank you, Eric!17 September 2022 at 11:39 am #612553
In outburst, ~ 0.15 mag flickering.
Attachments:1 October 2022 at 11:46 am #612760
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
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.
Attachments:1 October 2022 at 1:16 pm #612762
Good to see you back in action Max. Sounds like you’ve had a rough patch.2 October 2022 at 11:32 am #612789
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.
- This reply was modified 5 months, 3 weeks ago by Maxim Usatov.
- This reply was modified 5 months, 3 weeks ago by Maxim Usatov.
Attachments:2 October 2022 at 5:13 pm #612796
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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