[vsnet-campaign-deltavel 22] DELTA VELORUM almost figured out

[Sebasti若n Otero <varsao@fullzero.com.ar>]

Lew Cook has suggested recently that a conversion problem between JD and UT
could end in a 0.5 day discrepance.
Well, it wasn't exactly the case, but there were 1 full day errors in the
JD's for the 1989 eclipses!!
That accounted for the 0.06 day difference in period found if using the 1989
observations.

So there wasn't an incredible high decreasing trend in the period or
something like that...
And that's very good news because now the period is very well determined.

The new figure is 45.15100 days (+- 0.0005)

NEW ELEMENTS:    I  = JD 2451308.621 + 45.15100 x E
                                    II  =  JD 2447850.70  + 45.15100 x E

We were incredibly lucky that both primary and secondary eclipses between
1989 and 1997/8 are separated exactly by 66 epochs: EXACTLY THE SAME... this
allowed us to notice any error and we are also able to say that the
secondary eclipse occurs 19.706 days later than the primary, at phase 0.4365

It has also been found that a 27.10 day period is also a "perfect" fit ...
BUT only for 7 of our 8 eclipses.
The 2451147.72 event is not expected by this shorter period, which predicts
an eclipse on 2451146.06.
SO, November 12/13 observations are very important to rule out this period
definitively. (unfortuntely, the 2451147.72 event was poorly observed and I
could only detect a 0.1 magnitude fading...:-(( )

We're just a couple of steps away of our goal. KEEP OBSERVING!

Cheers,
Sebastian.

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