MBCAA Observatory
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KU Her: a slow irregular variableObserved: 12, 13, 14, 15, 19 July, 5, 18 Aug, 5, 6, 12, 15, 19, 20 Sept, 2, 4, 13, 14, 15, 16, 18 Oct 2007Michel Bonnardeau
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ID | RA(J2000) | DEC | V | B-V | V-Rc | Rc-Ic | V-Ic |
comp | 18:26:09.44 | +12:17:37.2 | 11.914 | 0.748 | 0.444 | 0.432 | 0.876 |
check | 18:26:23.68 | +12:15:47.2 | 10.892 | 0.665 | 0.383 | 0.358 | 0.738 |
The measured b,v magnitudes may be transformed
for the instrument response. The transformed B,V magnitudes are then:
V = v + TvTbv*[(b-v)-(Bc-Vc)]
B = b + TbTbv*[(b-v)-(Bc-Vc)]
Bc,Vc are the magnitudes of the comparison star. The transformation coefficients
were measured HERE;
they are:
TbTbv = 0.002 +/- 0.027
TvTbv = -0.025 +/- 0.015
The transformed R magnitudes (Rc filter) are computed from the observed r magnitudes the same way:
R = r + TrTvr*[(v-r)-(Vc-Rc)]
with the transformation coefficient:
TrTvr = -0.134 +/- 0.017
And the transformed I magnitudes (Ic filter) from the observed i magnitudes:
I = i + TiTri*[(r-i)-(Rc-Ic)]
with the transformation coefficient:
TiTri = 0.022 +/- 0.011
The transformed light curves:
Blue: the B measurements, shifted by -1.0 mag;
Green: the V measurements;
Red: the Rc measurements, shifted by +1.0 mag;
Brown: the Ic measurements, shifted by +2.5 mag.
The error bars are computed from +/- the 1-sigma statistical uncertainties
and the 1-standard deviations on the transformation coefficients.
The check star measurements are reported in the ASAS1826+12 page.
The (transformed) B, Rc, Ic magnitudes as a function of V:
Blue: B magnitudes; Red: Rc magnitudes shifted by +2.2 mag; Brown:
Ic magnitudes shifted by +3.0 mag.
As the star becomes brighter in V, it becomes brighter in B at about the
same rate (slope +1.00), in Rc at slower rate (slope +0.49), and stays
almost constant in Ic (slope +0.07).
Telescope and camera configuration.
Computer and software configuration.
Transformations for differential photometry.
Transformation coefficients: B, V measurements.
Transformation coefficients: V, Rc measurements.
Transformation coefficients: Rc, Ic measurements.
Pulsating stars and its links.
ASAS1826+12, a Cepheid in an eclipsing binary system, in the field of view of KU Her.
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