5 August 2022 at 7:38 pm #611811
I see the dilemma, Max (also shows rage pitfalls CV observers can get into with less than ideal data). If you can confidently and consistently compensate that would be the way to go (sorry!). In any case, it would be important to identify those eclipses where there is some kind of uncertainty in assignment of type.7 August 2022 at 2:43 pm #611840
Yep, I’ll use question mark.
Eclipses No(s): 63, 64, 65 (next day)
Profiles: U/N/A, U/N/A, V/N/A
- This reply was modified 1 month, 3 weeks ago by Maxim Usatov.
Attachments:7 August 2022 at 3:28 pm #611844
Looks slightly shallower, as expected, Max8 August 2022 at 12:19 pm #611854
Eclipses No(s): 66
Another surprise from CG Draconis – a post-egress hump (PEH) during the very early rising stage of the outburst, combined with high orbital hump amplitude – a U/H/PEH type profile, seen first. There was an interruption in data right after the PEH peak, but we can still see it was rather narrow.
At this state the white dwarf’s accretion disk must still be dim and cold, or at least partially hot, as the bright spot is prominent, peaking at phase 0.85 when it’s directly facing Earth. Its amplitude almost reaches 0.2 mag, making it a “high” hump in my classification.
What normally follows is an asymmetric, slower egress, however, this time we have an opposite case, I think, caused by a PEH. peaking at approximately phase 1.1. This phase coincides with the emergence of the bright spot on the other side of the eclipse. This could signify that the diameter of the bright spot is bigger than the thickness of the accretion disk, or, perhaps, that the disk is unusually optically thin at this early stage of the outburst.
It would be really interesting to have some input on these speculations. Although I have only recorded two eclipses during the rising stage of the CG Dra outburst, I would expect asymmetric egress, with the bright spot concealed by the disk on the other side of the eclipse.
If the disk is so unusually transparent tonight, what suddenly caused it? We have seen no PEHs during previous eclipses after the bright outburst. If the bright spot is unusually large now, extending beyond the accretion disk, which is supported by the absence of the standstill on the egress, then does this signify an increased accretion rate? If so, what has suddenly caused it? We have seen that there was no PEH at all yesterday – the eclipse was asymmetric.
The more data is being collected, the more questions I have.
Attachments:8 August 2022 at 1:34 pm #611856
I have found a V-shaped counterpart to this U/H/PEH eclipse, observed once at quiescence on May 28. I have called it Sharp-V/H/HA back then – high orbital hump, highly asymmetric. (See attachment, tonight’s U/H/PEH on the left, the Sharp-V one on the right.) Looking at the phase plots, I see both profiles are very similar, so I will rename the May 28 profile to V/H/PEH.
Attachments:8 August 2022 at 1:57 pm #611858
That is a dramatic eclipse Max! Seems to be enhanced by the preceding hump.9 August 2022 at 11:57 am #611867
Eclipses No(s): 67, 68
U/N?/A + U/L/S eclipse. Two different profiles on the same night, although there is no clear cut line where eclipse becomes asymmetric in my system. The latter eclipse is still slightly asymmetric.
Attachments:9 August 2022 at 3:08 pm #611875
Interesting to see them superposed on the brightening trend line12 August 2022 at 12:05 pm #611918
Eclipses No(s): 69, 70
Poor data quality. I assume poor transparency and occasional clouds, but difficult to say exactly why remotely.
Attachments:12 August 2022 at 4:21 pm #611928
Yes, probably poor transparency and moonlight interference, Max.24 August 2022 at 12:20 pm #612074
Back from the vacation. The telescope was collecting data, 2243 observations have been made for period August 14 to 23.
August 14, 2022, State: Quiescence
Eclipse No. 71, Profile: V/N/A
August 15, 2022, State: Quiescence
Eclipse No. 72, Profile: V/N/A
Eclipse No. 73, Profile: V?/N/A
August 17, 2022, State: Quiescence
Eclipse No. 74, Profile: ?/H/? – Intermittent data.
August 18, 2022, State: Quiescence
Eclipse No. 75, Profile: U/N/A
Eclipse No. 76, Profile: U?/N/A
August 19, 2022, State: Rising
Eclipse No. 77, Profile: U/L/S – Accretion disk becomes bright.
August 20, 2022, State: Outburst
Eclipse No. 78, Profile: U/L?/S
August 21, 2022, State: Outburst
Eclipse No. 79, Profile: U/L/PEH
Eclipse No. 80, Profile: U/L/PEH
Post-Egress Humps developed at the peak of the outburst, peaking at phase ~ 1.125.
August 22, 2022, State: Fading
Eclipse No. 81, Profile: U/L/S (brightening at a late phase due to the overall fading)
August 23, 2022, State: Fading
Eclipse No. 82, Profile: U/L/S (brightening at a late phase due to the overall fading)
Attachments:24 August 2022 at 12:25 pm #612083
Welcome back, Max. I was getting worried! Good to see that data have been collected in the meantime24 August 2022 at 1:05 pm #612084
Thanks, Jeremy! Good test for the autonomous operation. Looks like our scripts are now handling most of the software/hardware random bugs. At this point, I simply define the object, area of the sky and the A1 telescope wakes up, cools down, homes the mount, centers the focuser, slews, begins the imaging plan when the object is visible, etc – once the roof opens. The server in London data center pulls all the FITS in the morning, does photometry and I get e-mails with BAA/AAVSO report files. No interaction required whatsoever except for to produce the charts. Hopefully just a little more effort with the web UI interface and we can begin serving time for BAA on it.
I see that for some reason the most interesting curve from August 21 with PEHs has failed to upload. I’m attaching it here.
- This reply was modified 1 month, 1 week ago by Maxim Usatov.
Attachments:24 August 2022 at 2:50 pm #612087
Impressive set up, Max. Looks very reliable indeed.27 August 2022 at 8:11 am #612149
Very intermittent data will be uploaded during the next few days, won’t post charts.
Attachments:30 August 2022 at 9:50 am #612177Stewart John BeanParticipant
I had a look at the AAVSO curve, dominated by Max’s data of course (impressive). The last period 2459700 to present reminds me of an ER UMa star in that there are two bright outbursts with a series of smaller ones between. The brighter outbursts seem to be 70 days apart.
There are no TESS observations unfortunately.
Ive added it to my SLOOH watch list for Canary.
Stewart30 August 2022 at 9:54 am #612179Stewart John BeanParticipant
With a screen shot
Attachments:30 August 2022 at 11:55 am #612182
Thank you, Stewart.
Eclipses No(s): 83
Got some poor quality data despite the clouds, U?/N?/A profile.
Attachments:30 August 2022 at 7:53 pm #612185
Nice to see you continuing despite the inclement wx, Max.1 September 2022 at 4:01 pm #612202
Thank you, Jeremy! The mystery of CG Draconis has to be solved!
Eclipses No(s): 84, 85
U/N/A + ?/N/? eclipses, typical for quiescence. Post-egress hump peaking at phase ~ 1.2 on the first eclipse, coinciding with the reappearance of the bright spot on the other side of the eclipse.
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