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GSC 0279:0321 (Michael K.'s star) is a W UMa
I finally reduced my data from Wednesday night. The light curve
definitely turned over after the maximum as Michael had argued. The
scatter in my C-K measures was about 0.008 mag and didn't change much
as the field got to high airmasses, so I was comfortable that the V-C
variation down in the soup was real. Here is a plot of my differential
V mags and the C-K's:
http://binaries.boulder.swri.edu/systems/g0279_0321/g279_06jun2002.gif
So, with the continuous variation, I knew we couldn't have an eccentric
orbit system with period near a day. It was more likely to be a W UMa
type with P near a quarter day or so. I found that P=0.2898d gave a
phased light curve that is clearly from a W UMa system. Here is a plot
of my and Michael's data phased with that period:
http://binaries.boulder.swri.edu/systems/g0279_0321/g279_phased.gif
The secondary eclipse is slightly shallower than the primary according
to Michael's data. My very rough (eyeball fit only) ephemeris for this
one is
2452425.3 + 0.2898*E
More times of minimum would help tie that down. I'll append predictions
of primary eclipses for the next few days below. It's a pretty run of
the mill W UMa with partial eclipses. Nothing too exciting from a light
curve analysis point of view since we have partial eclipses and thus
won't have a very good handle on the mass ratio. So, I probably won't
spend any more telescope time on this one.
BTW, I used GSC 0279:0536 as C and GSC 0279:0287 as the K.
Dirk
Dates for the occurrence of phase: 0.0000
2452434.8634 9 Jun 2002 8.72 UT ( 8H 43M 18S)
2452435.1532 9 Jun 2002 15.68 UT (15H 40M 36S)
2452435.4430 9 Jun 2002 22.63 UT (22H 37M 55S)
2452435.7328 10 Jun 2002 5.59 UT ( 5H 35M 14S)
2452436.0226 10 Jun 2002 12.54 UT (12H 32M 33S)
2452436.3124 10 Jun 2002 19.50 UT (19H 29M 51S)
2452436.6022 11 Jun 2002 2.45 UT ( 2H 27M 10S)
2452436.8920 11 Jun 2002 9.41 UT ( 9H 24M 29S)
2452437.1818 11 Jun 2002 16.36 UT (16H 21M 48S)
2452437.4716 11 Jun 2002 23.32 UT (23H 19M 6S)
2452437.7614 12 Jun 2002 6.27 UT ( 6H 16M 25S)
2452438.0512 12 Jun 2002 13.23 UT (13H 13M 44S)
2452438.3410 12 Jun 2002 20.18 UT (20H 11M 2S)
2452438.6308 13 Jun 2002 3.14 UT ( 3H 8M 21S)
2452438.9206 13 Jun 2002 10.09 UT (10H 5M 40S)
2452439.2104 13 Jun 2002 17.05 UT (17H 2M 59S)
2452439.5002 14 Jun 2002 0.00 UT ( 0H 0M 17S)
2452439.7900 14 Jun 2002 6.96 UT ( 6H 57M 36S)
2452440.0798 14 Jun 2002 13.92 UT (13H 54M 55S)
2452440.3696 14 Jun 2002 20.87 UT (20H 52M 13S)
2452440.6594 15 Jun 2002 3.83 UT ( 3H 49M 32S)
2452440.9492 15 Jun 2002 10.78 UT (10H 46M 51S)
2452441.2390 15 Jun 2002 17.74 UT (17H 44M 10S)
2452441.5288 16 Jun 2002 0.69 UT ( 0H 41M 28S)
2452441.8186 16 Jun 2002 7.65 UT ( 7H 38M 47S)
2452442.1084 16 Jun 2002 14.60 UT (14H 36M 6S)
2452442.3982 16 Jun 2002 21.56 UT (21H 33M 24S)
2452442.6880 17 Jun 2002 4.51 UT ( 4H 30M 43S)
2452442.9778 17 Jun 2002 11.47 UT (11H 28M 2S)
2452443.2676 17 Jun 2002 18.42 UT (18H 25M 21S)
2452443.5574 18 Jun 2002 1.38 UT ( 1H 22M 39S)
2452443.8472 18 Jun 2002 8.33 UT ( 8H 19M 58S)
2452444.1370 18 Jun 2002 15.29 UT (15H 17M 17S)
2452444.4268 18 Jun 2002 22.24 UT (22H 14M 36S)
2452444.7166 19 Jun 2002 5.20 UT ( 5H 11M 54S)