MBCAA Observatory

KZ Hya time keeping

Observations: 25, 27 April, 18, 19 May 2004

Michel Bonnardeau
28 June 2005


Three pulses are observed for this SX Phe pulsating star. They are 29 mn late from the 29 yr old GCVS ephemeris.


KZ Hya is a pulsating star of the SX Phe type with a period of 85 mn. According to the GCVS one has the ephemeris for the pulses:
T0 = 2442516.15836 (13 April 1975)
P0 = 0.0595104212


KZ Hya was observed with a 203 mm f/6.3 SC telescope, a SBIG ST7-E camera (KAF401E CCD) and a Rc filter. 170 images were obtained. The comparison star is Tycho 6638-00764 with an assumed Rc magnitude of 9.8. The check star is Tycho 6638-00842 with a measured Rc magnitude of 9.63 and a standard deviation of 0.04.

An example of a light curve:

Red: KZ Hya, green: the check star shifted by +1 mag. The error bars are the +/- 1 sigma statistical uncertainty. KZ Hya was very low over the horizon and the atmosphere unsteady.

All the light curves are here.

When folded with the period P0, the observations give the phase plot:

Comparison with the ephemeris

Three pulses are observed at: 121.412, 123.376, 144.382 (HJD - 2453000). The uncertainty is about +/-0.0015. They are 29 mn late from the 29-yr old GCVS ephemeris.

It would be interesting to know if the star is slowing down or if it experienced some "glitch" in a recent past. More observations would tell.

Technical notes

Telescope and camera configuration.

Software and computer configuration.

Site map


Write to the author

2005-2006 observations and binary nature

Observations submitted to the AAVSO International Database, observer BZU.

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