Affiliation
American Association of Variable Star Observers (AAVSO)
Tue, 07/14/2020 - 17:07
AAVSO Alert Notice 710 announces an observing campaign beginning now on the UXOR ASASSN-V J181654.06-202117.6. Please see the notice for details and observing instructions.
To stay informed about this campaign, subscribe to this forum thread (option 1 below under Subscribe) - see feedback from the PI, comments and questions from observers, and notes from AAVSO HQ. Add a post yourself - join in the discussion about this interesting target!
Many thanks, and Good observing,
Elizabeth O. Waagen, AAVSO HQ
Hello everyone,
I'm on the edge of my seat looking at this star, and I'll be posting new analysis, theories and predictions to the github as soon as I have them. I'm grateful for all the observations made until now, and I really would like you to keep observing J1816 for the next 2-3 months. Because the star is happening to become elusive at this time of year, I want to ask all of you to take observations beyond airmass 2 at least once per night per filter available with the lowest airmass available to you (though the more the better). I don't mind if your observations drop below 40 degrees altitude, or even 30 degrees altitude.
Thanks a lot and clear skies!
Dirk van Dam
Hi Dirk/everyone, at latitude -41 degrees and running on summer time, J1816 is setting fast. My current observations are starting at 35 degrees alt. Trying to get observations as long as possible but clouds/weather also continuing, presently can't win!!!! - would love to see the predicticted reduction/minimum!!!
cheers, Merv
Hello Everyone,
I just wanted to let you know that I've updated the GitHub page to include lots of plots animations and the basic story of J1816. Feel free to explore the whole repository, but the main information of interest will be found at https://github.com/dmvandam/j1816/tree/master/public
Cheers,
Dirk
AAVSO Alert Notice 723 announces a new, second campaign on the UXOR ASASSN-V J181654.06-202117.6 (the previous campaign was announced in Alert Notice 710). Please see Alert Notice 723 for new instructions (including spectroscopy), a beautiful light curve incor porating your data, and other information.
To stay informed about this campaign, particularly regarding any modifications to instructions from the astronomer, subscribe to this forum thread (option 1 under Subscribe in the first post in this thread) - see feedback from the astronomer, comments and questions from observers, and notes from AAVSO HQ. Add a post yourself - join in the discussion about this interesting target!
There is also a thread on this campaign in the Young Stellar Objects (YSO) forum.
Many thanks, and Good observing,
Elizabeth O. Waagen, AAVSO HQ
Observations last night shows the object brightness to be steady.
TG
Observed tonight almost down to airmass 3. Still steady.
TG
As of a couple of hours ago, no dip.
TG
Hello Everyone,
It looks like I was a little too enthusiastic about the two eclipses and the potential reflection symmetry about the midpoint. I was hoping that the slight change in eclipse shape between the 1st and 2nd eclipse (see the github page - public folder -- https://github.com/dmvandam/j1816/tree/master/public), could just be due to the asymmetry of the eclipse, but I guess this is not the case.
I've got some new potential insights on the system. It looks like there are long period variations (two sinusoids with a period of ~175 days and ~15 days) that I'm trying to filter out effectively and responsibly. From there I want to see if I can make a new prediction (if there is anything else that looks like a reflection). Based on this it is likely that the latter part of the eclipse will eventually be hidden by the sun.
I would like everyone to keep following the star for as long as possible because there are two possibilities I foresee. Either we will see eclipses coming along (this is based on predictions I have yet to make), OR, the star is quiescent and we are dealing with something totally different.
In the case the star is quiescent we could be looking at dust clumps (the star is classified as a Class I/II YSO, so containing a circumstellar disk) occulting the star (possible) or perhaps misaligned disks (just speculation at this point as I have no experience with this as of yet)...
Please keep following the star for as long as possible.
Thanks a lot and good observing!
Dirk
J1816 is getting too low on the horizon, unfortunately I have only a couple of nights left and then will have to wait until March.
cheers,
Juan Pablo
Juan Pablo,
Your observations are much appreciated, and I appreciate it that you've been following the star for so long. Thanks for your data, together with the rest I'm sure I can find out what this system is and we can make a great paper out of this!
Cheers,
Dirk
No dip yet and last night the last observation was at airmass 3. Should I continue observing this target?
Please advice.
Regards,
Josch
Hi Josch,
Thanks for continuing to observe J1816 for such a long time. I'm still hoping for a dip, but not sure if it will come (need to do some more rigorous analysis to be able to make a new prediction). I do think however that in about ~ 14 days there might be a rise in the flux of J1816, which is "relatively" sharp and non-sinusoidal. This is from seeing the same feature 3 times in the ASAS-SN (g) light curve spaced by approximately 200 days.
If you and anyone else can keep observing I would appreciate it significantly. J1816 will be setting for the season soon, and then we won't be able to do any observations until ~ March (which would either contain the eclipse or show it continuing -- which I wouldn't expect).
Kind regards,
Dirk
Ok everyone, I know that J1816 had pretty much disappeared from view and is barely rising(wherever you are), but it looks like the brightness might be dropping again thanks to the efforts of Josch. Please observe the star if at all possible (Josch is currently at airmass 4)
Cheers, Dirk
Hello Everyone,
I want to thank you all for the tremendous help and the enormous amount of data that has been collected. Unfortunately J1816 has pretty much set for the season and will probably pop up somewhere around March. We unfortunately did not see the star return to quiescent levels for long enough to judge the end of the eclipse. In fact there is reason to believe (see HMB) that the flux might have started to drop in these past few days. We do have enough to keep doing more and more analysis and I'll keep posting updates on the GitHub (https://github.com/dmvandam/j1816/tree/master/public). I would very much appreciate say two weeks of observations once J1816 rises again in ~ March to make sure the eclipse is in fact over.
Anyways, thanks all and I'll keep you posted,
Dirk
Hi Dirk, thanks for a most interesting object and great to see your analysis and possible physics in play. As soon as it rises again on my local horizon, I'll start collecting data as weather permits.
cheers, Merv
First Look at this object for the year ... at airmass 3.2 and in twilight ... was pretty much where I left it in early November ... 12.584V.
Steve.
Hello,
The object is now again visible to my scope down in Namibia.
I will try to have it amont my observations lists...
Br, Grzegorz
Grzegorz,
Thank you so much, the AAVSO e-mail in my inbox yesterday made me quite happy. Great to see that the intra night variability is still there. Some time this week I'll confirm whether the pulsation model agrees with the new data you've posted (ensures the long term stability of the pulsations!). Note to everyone: can you please check if J1816 is back in your sights. I'm not 100% sure that the eclipse is over (a star my supervisor is monitoring is still in whacky transit after a whole year!).
Clear skies,
Dirk
Hi all,
I wanted to thank you all for the great support in following up J1816. I can appreciate any more data that would be taken on the star, but I think we have observed enough to safely say that the eclipsing object is no longer transiting the star. I'm currently working on a separate project - a ring system fitting tool for light curves - so it will probably take me a while (about the summer) to further pick up the analysis of the data you've sent in. By that time I will also be reaching out to offer authorship on the paper. I had another question I would like to ask all of you who have provided data.
I'm going to be presenting to some elementary school kids and some middle school kids in September and giving a talk about astronomy focused on telescopes (forms and sizes) and be linking it to this study. I would really appreciate it (also for any other talks I might give on J1816 specifically), if you could send me a picture of yourself and of your setup (telescope). It doesn't have to be a recent picture, but I would really appreciate it, so we can inspire another generation of people and let them know that astronomy is available to anyone with their mind set on it.
Cheers,
Dirk
Silly me, you can't send me anything without an email address. It is dmvandam@strw.leidenuniv.nl