[vsnet-campaign-deltavel 13] Slightly shorter period?

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

Delta Velorum Campaign people:

Albert Jansen observations put the eclipse duration near 0.3 days. That's
exactly what I observed on May 10, 1999.  The primary eclipse seems to go
all the way to 2.3. The secondary eclipse is probably more than 0.1
magnitudes brighter. The secondary eclipse occuring at phase 0.44 is almost
identical to the newly discovered "eccentric EA" GSC 3992_0847 (see IBVS#
4807)
Galileo data seems to prove the eclipse is longer and probably the beginning
and end are missing in the visual observations. (Sequence is poor at
maximum...)

If I take the three more recent primary eclipses (1999-2000), the period
seems to be 45.15667 days. But it doesn't fit with Albert's 1989 photo= 0.5
day difference...
Obviously more observations are needed, but...
Analysing the secondary eclipse, again the best period is 45.15667 days. And
again, there is a difference with the 1989 Galileo's eclipse of 0.7 days.
There are only sparse data for the secondary eclipses but the period doesn't
seem to be longer at that time.
Paul Fieseler (Galileo Mission, JPL, NASA) suggested the possibility of a
period change some time ago.
If there was a period change between 1989 and 1997, it looks like it wasn't
gradual.
The information we'll collect on November 21st  will help us improving our
numbers, specially those concerning the phase of the lightcurve where the
secondary eclipse takes place, which in turn will allow us to speculate
about what was the period in 1989...

Also the 2450631.5 eclipse is a problem, because it suggests an even shorter
period or a longer duration. I bet for the latter.

The next eclipses based on a 45.15667 day period are centered at the
following dates:

JD 2451870.27 -  18.30 UT  November 21st  II Eclipse
JD 2451895.61 -  02.40 UT  December 17th  I Eclipse


Best wishes,
Sebastian.

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