[vsnet-chat 3788] RV: let's not be too late!

[Sebastián Otero <varsao@fullzero.com.ar>]

I forward this message from Albert Jansen that is of public interest.
Regards,
Sebastian.


Hello,

Thinking about the secondary minimum of Delta Vel next week and the
planning of our observations, I made some calculations.

89 times 45.15 days (your 'favorite' period) after 2447851.69 (Galileo)
comes out as 2451870.04 = Nov 21st, 13h UT. So far no problem.

But linear regression on the remaining four primary eclipses yielded a
period of (45.1455 +/- 0.0035) days. Therefore, if we take 45.142 days, the
minimum could happen at 2451869.33 = Nov 20th, 20h
UT !!!

In that case, the phase of secondary minimum would turn out as 0.418. Maybe
this is impossible, and are you sure it should be much closer to 0.435.

Now, 0.435 times 45.15 days after 2451850.45 (my recent observation) comes
out as 2451870.09 = Nov 21st, 14h UT.

Taking into account that the eclipse will start about 11 hours before and
end about 11 hours after minimum, I think our observing window must stretch
      FROM  November 20th, 9h UT  UNTIL  November 22nd, 1h UT ,
in order to be sure that we don't miss this all-decisive moment!!

This implies that we all should start on Monday evening, Nov 20th, and
observe on Tuesday, 21st, as well. If photoelectric equipment needs some
calibration beforehand with Delta at maximum, this should be done TOMORROW,
Nov 19th.

If some (parts of) visual lightcurves could be fitted to the nice 11-year
old Galileo lightcurve, your period could be accurate to 0.001 day. And if
there will be p.e. observations, it would be 0.0001 or 0.0002 day.

So let's hope for the best, the weather can spoil all our good intentions,

Albert

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp