[vsnet-alert 10783] re ST Cha eclipse period

[bydra at Safe-mail.net]

"The other interesting point they make is that the system is eclipsing with a period around 7h... that should easily be tested by a few nights of time series."

Yeh, I read that bit.  Evidently when I read their comments I missed some bits that you've pointed out, though I remember the 'nova like' bit.

Now, the bit you've missed is the paper they quote they got the data from for their 7 hour eclipser :-

http://www.konkoly.hu/cgi-bin/IBVS?1049

that ain't much of a density of data for claiming seven hour eclipsers for an object that ain't constant much out of "eclipse", with no real single night runs at any particular brightness states.  Dunno, I might look at it later.  0.8 mag ish range off photograph plates.

Rod Stubbings has logged a ton of visual stuff of this object by the look of aavso archives, btw.  Experienced observer.

ASAS3 say the period is 27.3 days, which does sound like an orbital period.  The Moon's.

You can get a peak at around 6.93 hours at a pinch, though it's no more significant than many another to speak of, and given the constant brightness changes, the phase plot shows nothing, but here's the data in case you want to play yourself.  Of course, we're down in the data noise here, pushing asas3 to it's limits, and the minimum mags may be below the asas3 limit still.

But looking at that IBVS source the ~7 hour period of the 1998 paper is likely spurious, at least in terms of eclipsing events.

Cheers

John

Data courtesy ASAS3

HJD--2450000    ASAS3 V
1869.8563	14.224
1871.8425	13.952
1873.8466	14.177
1875.8343	13.708
1877.8240	13.587
1879.8222	13.807
1881.8177	14.051
1885.7864	14.341
1889.7995	14.395
1902.8016	13.968
1904.7839	13.618
1906.7838	13.802
1908.7732	13.773
1915.7594	14.195
1918.7209	14.099
1922.8292	14.279
1924.8067	14.117
1925.7954	13.962
1926.7918	14.365
1928.8178	14.188
1929.7947	14.081
1931.8250	13.433
1932.8298	13.706
1933.8572	13.654
1935.6517	13.876
1936.7993	13.938
1940.7392	14.349
1945.8104	13.903
1958.7154	13.864
1962.7366	13.577
1963.7113	13.702
1964.7123	13.978
1965.6987	14.163
2027.5808	14.167
2030.5520	14.047
2032.5587	14.425
2052.5022	14.047
2079.4704	13.956
2087.4785	13.771
2103.5003	13.839
2105.5220	14.122
2116.4807	14.587
2130.4765	13.923
2222.8419	13.684
2225.8449	13.510
2225.8449	13.464
2443.4904	13.994
2460.4566	13.573
2641.7841	13.814
2657.7695	13.792
2670.7550	13.907
2672.8202	13.764
2684.7086	14.108
2692.7989	13.653
2696.7569	13.746
2726.8687	13.675
2735.8632	13.881
2738.8437	14.225
2750.8281	13.675
2754.7827	13.736
2756.7259	14.220
2757.8189	14.410
2782.7404	13.731
2784.6417	13.734
2786.6102	13.787
2821.6029	14.217
2876.4917	14.031
2971.8461	13.503
2981.8232	13.762
3008.8075	13.775
3018.8011	13.701
3052.7240	13.875
3071.7626	14.035
3073.8110	13.644
3076.6535	13.755
3086.7681	14.538
3093.6736	13.998
3114.6171	13.942
3127.6579	13.226
3153.6597	14.036
3189.6400	13.448
3357.8226	14.279
3402.7992	14.123
3405.7508	14.232
3411.7453	13.602
3414.7236	13.652
3431.7868	13.554
3433.8182	13.777
3442.6747	14.014
3450.7027	13.586
3450.7043	13.613
3453.6266	13.636
3465.7997	14.095
3473.5869	13.716
3475.7089	13.623
3477.6583	13.778
3497.8025	13.672
3501.4924	14.008
3503.5458	14.306
3509.6305	14.230
3521.6106	14.347
3523.6144	14.407
3525.6337	14.369
3554.5747	14.667
3556.5956	14.150
3559.5928	14.383
3570.5590	14.059
3574.5482	13.582
3576.5760	13.634
3584.5597	14.469
3587.5039	14.287
3589.5306	14.422
3592.4888	14.021
3603.4944	13.511
3607.4899	14.247
3675.8682	13.660
3701.8531	13.594
3725.8207	14.087
3728.8444	13.818
3739.8180	13.585
3742.8236	13.531
3745.8440	14.089
3757.7951	13.603
3760.7859	13.642
3772.7677	14.028
3788.7683	14.103
3791.7128	14.115
3803.8392	13.484
3805.7795	14.166
3810.8014	14.006
3813.6444	14.042
3815.6999	14.082
3817.7094	13.759
3819.7641	13.549
3822.6241	13.746
3834.6963	13.615
3850.6598	13.820
3861.5935	14.272
3863.5923	13.557
3865.6028	13.741
3867.6485	13.861
3874.7281	14.316
3881.7500	14.165
3890.5633	14.286
3894.6285	14.074
3902.5005	14.075
3906.5590	14.091
3908.5570	14.429
3913.6533	14.260
4109.8369	14.903
4131.7641	14.318
4141.8052	13.706
4144.7369	13.789
4159.7608	13.812
4161.7503	13.754
4163.7578	13.866
4165.7808	13.543
4181.7173	14.017
4193.6539	13.526
4198.7036	13.719
4213.7037	13.512
4227.5946	14.064
4229.6046	14.107
4233.6117	13.626
4235.6100	13.770
4237.6269	13.979
4246.5570	13.965
4272.6172	13.728
4282.5800	13.360
4284.5939	13.492
4286.5883	13.439
4294.5629	14.150
4296.5578	14.406
4305.5369	13.769
4307.5634	13.649
4330.4934	13.525
4333.5002	13.636
4342.4847	14.173
4430.8296	13.545
4458.8021	13.759
4484.8237	13.678
4487.7902	13.846
4497.7819	13.811
4506.7434	13.983
4508.8054	13.530
4511.7265	13.685
4522.8149	13.815
4532.6773	13.865
4535.7682	13.471
4537.7693	13.695
4564.6526	14.599
4566.6615	14.257
4568.6713	13.420
4570.6519	13.662
4572.6249	13.808
4592.7196	13.548
4594.7355	13.533
4596.7463	13.782
4607.6273	13.639
4622.6397	13.937
4626.6537	13.755
4639.6359	13.862
4641.6601	13.982
4648.5999	14.276
4655.5079	14.110
4657.5573	13.485
4659.5994	13.394
4674.5222	13.802
4681.5001	14.350
4685.5145	13.947
4687.5272	14.046
4690.5148	13.509
4702.4737	13.886
4802.8219	14.554