[vsnet-chat 2969] NSV4189 Hydrae - Revised Epoch and Period

["Peter F Williams" <pfwilliams@onaustralia.com.au>]

Hello All,

Further to vsnet-chat 2560, using the V magnitudes for comparison stars in
the field of NSV4189 Hya (kindly obtained by Arne Henden), I have
redetermined the magnitude estimates for this long period variable.  These
revised magnitudes have led to a slight change in the shape of the light
curve and dates of maxima determined from a mean light curve.

This has in turn led to the following revised epoch and period for maximum
light :

JD 2450190 + 448 days.

The 448 day period, although still preliminary. gives much reduced scatter
in the O-C values when compared to the originally suggested 465 day period
(vsnet-chat 2560), as shown in the following table:

OBSERVED	+/- 448 DAYS	O-C	+/- 465 DAYS	O-C
MAXIMUM

2449730	2449742	-12	2449725	+5
2450190	E		0	0		0
2450640	2450638	+2	2450655	-15
2451075	2451086	-11	2451120	-45
2451540	2451534	+6	2451585	-45

It is still very early days in the study of this star but the above revised
data appears to give a better indication of its character.  NSV4189
continues to decline from the most recent maximum being at magnitude 13.8
on 2000 May 21.4UT.

This revised data further demonstrates the value of a reliable comparison
star magnitude sequence.

Regards

Peter Williams
Heathcote NSW

VSNET Home Page

Return to Daisaku Nogami

---

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