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[vsnet-ecl 338] DE Dra and DK Cam
------ DE DRA ------
>From: Thom Gandet <tgandet@mindspring.com>
>
>Dear Sebastian and Kari,
>
> DA Dra = 71 Dra = HD193964. This star is also a known spectroscopic
>binary. 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; the eccentricity is 0.04, omega is
>291.2 However, the 4th edition of the Bright Star Catalogue (1982)
>gives a more precise (not necessarily more accurate) value of the
>spectrographic period: P=5.298111 days. I don't know the origin of
>that more precise period.
>.. interesting stuff..
Dear Thom, Sebastian, Chris and others,
I looked through my data file of DE DRA 11/1999-5/2000 (2*85 obs)
and my logbook (some obs) and found some deep minima.
Typically DE Dra is normally around 5.6..5.8 in my obs.
"Observed mags" are compared to e HIP99500 and b HIP98962.
Date UTC HJD O-C(gcvs) observed mags
3/4 Aug 2000 21:12 51760.385 O-C= +0.284 d 591,614 deepest
19/20 Aug 2000 19:34 51776.317 O-C= +0.323 d 586,609 minima
not so deep but nearly are:
3/4 Aug 2000 22:23 51760.434 O-C= +0.334 d 579,599
30/31 Dec 1999 15:27 51543.144 O-C= +0.263 d 581,604
16:33 51543.188 O-C= +0.307 d 576,589 near normal
23/24 Nov 1999 22:33 51506.440 O-C= +0.645 d 576,605
26/27 Jul 2000 21:43 51752.406 O-C= +2.902 d 586,599 II min ?
22:48 51752.451 O-C= +2.947 d 589,604
With symmetric II min assumption I get O-C= +0.253 d and +0.298 d
13/14 Aug 2000 19:55 51770.331 O-C= -0.365 d 579,599
00.15 51770.512 O-C= -0.184 d 581,594
10/11 Jan 2000 15:23 51554.141 O-C= +0.664 d 579,599
19:48 51554.325 O-C= +0.848 d 578,600
11/12 Jan 2000 15:26 51555.143 O-C= +1.666 d 583,609 erroneous ?
I used GCVS elements 42626.286, P=5.298036 d D=0.25 d.
So O-C could be even about +0.3 d now and new period could be 5.2982 d.
My periodogram program suggested for my DE Dra file
periods 0.541,11.50,11.55,11.64, 11.9475, 95.6 days.
Amplitude about 0.2 mag.
Curve looked cepheid-like curve. For some periods inverse cepheid..
. .
. . . .
. . .
------ DK CAM ------
>From: "Sebastian Otero" <varsao@fullzero.com.ar>
>
>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 always observe these DE Dra, DK Cam visually with B10x50 and B12x50.
ok, here is one DK Cam light curve:
-27 Mar 2001 DK Cam minimum GJD 51996.433 By Mr. Kari Tikkanen-
20 21 22 23 0 1 2 3 4 5 6 FIN wtime
18 19 20 21 22 23 0 1 2 3 6 UTC
:.....:.....:.....:.....:.....:.....:.....:.....:.....:.....:
: :
760+ :
: x DK Cam :- f -
: :
: x :
: :
+ x x :
: x :
: x :
: x :
: x :
770+ :
: x :
: :
: x x :
: :
+ :
: x x x :
: :
: :
: :
780+ :
m : x :
a : :~ k ~
g : :
:.....:.....:.....:.....:.....:.....:.....:.....:.....:.....:
I had in practice only one comp star f=+7.61, my 0.1-steps I assumed
0.1 mag maybe really only 0.06 or 0.15 mag ..
I had also comp star k as confirmation, I'd used that from beginning
if I'd known minima so deep. But during minima DK Cam got very close
k=+7.94 so I conclude my 0.1 steps for this star are really 0.15 mags..
And you should read 780 =really approx= +7.90.
But I don't think there's room for two hours error.
At 4 o'clock our wintertime dawn was arriving..
My comp stars for DK Cam
HIP magHIP magTYC B-V Red corr mag that I used
k 19377 760 761 +0.043 +7.61
f 21555 791 792 +0.172 +7.94
Unfortunately on this latitude +65o here bright nights started a week ago.
I see dark nights next time at the end of August..
Also weather forecast is rainy for this evening.
It would have been interesting to try to "catch" FM Leo now.
Soon I'm left with Beta Lyrae alone. On the other hand something odd vierd
is going on there just now..
Regards,
Mr. Kari Tikkanen, Oulu, Finland.
vsnet-adm@kusastro.kyoto-u.ac.jp
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