[vsnet-chat 4201] Re: DK CAM hipep.. THANKS!

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

>> DA Dra = 71 Dra = HD193964.

**Hi, Thom:
               Actually it is DE Dra, ... or the namimg rules have changed!!
:-))


>>The 8th catalogue of SB orbital elements (Batten A.H., et al,
Publ. Dominion Astrophys. Obs. 17 (1989), gives a somewhat different
period of 5.2981, T0=JD 2441140.485 (time of periastron passage), based
on spectra obtained prior to 1973

 **Actually it has nothing to do with the epoch published in the GCVS (??)
It falls in between. using the 5.298111 day period we have:
JD 2442623.956 **GCVS= JD 2442626.2861** JD 2442629.254

The former is 2.3301 days before and the latter is 2.968 days after the GCVS
epoch.
Whatever. I used the new epoch and period and it generally eclipses fall in
the gaps in Hipparcos data, but:

JD 2448349.1136  5.71V- maximum
prediction:  JD 2448349.2206

0.11 days away from eclipse nothing is detected.

Another observation of interest:

JD HIP=   2448438.858  5.72V
JD pred=  2448439.288

JD HIP=   2448317.112   5.72V
JD pred=  2448317.432

Probably the period is no less than 5.298111 days... but nothing else can be
said.


>>The potential error in the predicted times of eclipse from using
the spectrographic period and the photometric period is roughly 0.1
day.  If the duration of primary eclipse is short, as I suspect, then
the Hipparcos observations could well have missed it.

**That's possible, we all know Murphy's Law.
"He" was also responsable for offering us a false "eclipse" observation in
delta Velorum's data and I suspest is giving me another headache with
another single "period-breaker" observation that it's ruining my predictions
on the HIP eclipser V1154 Tauri.
I'm sending a separate e-mail for this one, since today it is when my
prediction could be proved true or false.

And regarding delta Scorpii, time will tell if there is any periodicity in
the visual variations. The two maxima shown in our paper are simmetrical.
But recently the star has remained bright near 1.8. The two brighter sharp
peaks are some 70 days apart (JD 2451752 - 2451823) and the last maximum
although difficult to detect seem to have occured near 2451978, more
consistent with a 77 day variation.
But since mass loss and irregular variations are probably involved it is
just an approximation.
But interesting..

Cheers,
Sebastian.



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