[vsnet-ecl 337] Fw: FM Leonis - Another HIP EA

["Sebastian Otero" <varsao@fullzero.com.ar>]

> About last night's message about V1154 TAURI, I forgot that there was A
> RECENT ECLIPSE OBSERVATION from Kari,

Yes, I am going crazy with too many EB's... I meant DK Cam not V1154 Tau...
Sorry again.

I have used the new eclipse observations by Kari and I found a slightly
longer period than the proposed by Chris.
I do lightcurve fitting on Hipparcos observations to get my periods.
I nticed that the Hipparcos dataset on this one includes some observations
that are off more than 0.05 magnitudes. This makes it all more difficult.
Given a certain rate of brightening/fading, this should be symmetric as in
all EB's. However two or three observations in eclipse are very discrepant
with each other.
However, taking this problems in account, the period is always a little
longer.

Two moments of minima from Hipparcos are JD 2448160.05 and 2448660.99. They
are
41 cycles apart and give a period of 12.21805 days. And this is the shortest
period I could get, since actually the observations seemed to indicate that
the eclipses were at JD 2448160.04 and 2448661.00.
And now, introducing the 2001 eclipse (JD 2451996.433) we can use both HIP
minima and we can get:

JD 2448160.05 =  12.21778 d.
JD 2448660.99 =  12.21774 d.

It's always longer than 12.2176 days.
Using Hipparcos time difference between the two "well" observed eclipses, we
can now use the 12.21805 days deduced and this would have produced an
eclipse on JD 2451996.515 or 2451996.517 (...the same...) for both To 's.

The question is: have the eclipses been detected photometrically or
visually? Is it possible that actual minimum may have occured 2 hours later
than observed? (that's within the eclipse duration, so the detection could
have been made at the same hour, in part).
If your JD 2451996.433 minimum is that accurate, then the period is near
12.21774 days.
I think we need to keep observing.

Anyway, my predictions are now just half an hour later than those sent by
Chris

> I observed couple minima of DE DRA in Aug 2000 visually. They are
> on my logbook but not yet tapped onto file into my computers.
> I use RANDOM method for these small "milli"variables. (It means
> without ephemeris).
>
> My comp stars for DE DRA are:
>  e  TYC 4236-2502-1  HIP 99500 F5V    T48= W
>  b  TYC 4236-2503-1  HIP 98962 K3III

Now that Thom Gandet (vsnet-chat 4195) has provided a better ephemeris, it
would be good to check it against your observations. Have you tried?
Tomorrow it's going to be raining here so maybe if you are intrerested you
can take a look at FM Leonis and see if you catch it faint.

It is very interesting this kind of work. Let's keep doing it!

Cheers,
Sebastian.


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