Fri, 08/22/2014 - 22:23
Hello! I have been following eclipsing short period variable RY AQR this season. I reviewed my data for the last couple of months. The curve for observations for 29June2014 seem to be significantly fainter than the curve for the other days of observations.
What might have caused this? Equipment or technique? Best regards.
Mike
Without seeing your images, it would be difficult to answer. However, I looked at data for RY Aqr for the past year+ in VStar. Another observer saw a similar minimum mag about a year ago. Do you have 3 minima observed this year? That's what shows up? VSX reports a range of 8.8-10.2. Your fainter mag is 10.2.
I believe this is an EA type EB (like Algol) so there would be primary and secondary minima. One would be fainter than the other.
Ken (MZK)
Further to Ken's note... by zooming in on the LCG, I see you caught a minimum at V=10.2 at about 245 6838.242 (just an eyeball estimate, and without doing heliocentric correction). Going to the BRNO O-C Gateway page, and entering the above JD, their O-C diagram confirms the above JD is close to when a primary minimum would have occured.
Because the period is almost a whole number of days ( 1.966... ), you can observe for a long stretch without catching an eclipse, or conversely, if you catch one on a given night, you'll catch primaries and secondaries on alternating nights for the next week or so. Each primary eclipse will be about 48 minutes earlier (edited! had said later, but that is obviously wrong!) in the night than the last one. Same for secondaries.
You might want to take all your data, and "phase it", i.e. fold it in to one period, to see what the light curve looks like through the orbital period of the star.
For more info on the above, and links to those resources, check out the web pages of the Eclipsing Binary Section.
Regards, Gary Billings
Hello! Thank you for your note. I have recorded just the one magnitude dip. There are about 3 more months of observing, though th number of observations each observaton night will go down steadily from now on. Best regards.
Mike
Hello! I just recorded the third major dip in RY AQR's curve over the past 6 months. Each deep decrease in magnitude is about 2 months from the previous dip.
The listed period is about 2 days. What might cause these dips if they are occurring about every two months? Or would they simply reflect the fact that the actual period is close to two days and monitoring twice a week might not catch the decline but once every two months? Best regards.
Mike
Same story as back in August. The period, according to VSX, and I have no reason to contradict is 1.966 days. So if you catch an eclipse one night, you will on numerous subsequent nights (every second night, of course). Each cycle will come 2-1.966=0.034 days earlier, so after 1/0.034 cycles, you will be back where you started in terms of phase, i.e. about 29 cycles or 58 days.
This star is also one of the EBs in the AAVSO Legacy list, with ephemirides prepared by Gerry Samolyk, so you can plan your observing so as to nicely capture a whole eclipse, and derive a publishable time of minimum. Those ephemirides etc are available at the AAVSO EB Section website.
Ephemirides are also available for MANY more EBs at the Cracow site. Again, see the EB Section website for links and more info.
Cheers, Gary Billings
Mike
Thanks!
Mike