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[vsnet-ecl 354] zeta Aurigae eclipse 2001
>>Date : Thu, 3 May 2001
>>From : Kari Tikkanen <ktikkane@mail.student.oulu.fi>
>>To : vsnet-ecl@kusastro.kyoto-u.ac.jp
>>Subject: zeta Aurigae eclipse 2001
Zeta Aurigae eclipse 2001
observed visually
by
members of URSA.VSS
--------------------------------------------------------------------
CONTENTS
I Introduction
II Log-file of Observations
III Light curve of Observations
IV Mean light curve
V Minimum calculation and conclusions
--------------------------------------------------------------------
I Introduction
Somebit difficult red eclipsing binary
zeta Aurigae
was observed visually by Veikko M臾eland Kari Tikkanen,
two members of URSA.VSS in Finland using Argelander method.
Usually March and April are some of the clearest months in the year in
Finland for observing stars so this was good opportunity to observe
eclipse of zeta Aurigae.
Magnitudes were computed by Tikkanen's extinction calculation
DOS-program.
Unfortunately personal differences in eye red-sensitivity causes
problems as will be seen in light curve below.
We used map:
http://vsnet.ursa.fi/ursa/jaostot/muuttujat/kartat/zeta_aur.gif
--------------------------------------------------------------------
II Log-file of Observations
Explanations of Log file
rc Red-Corrected magnitude v=0.2(B-V)+Tyc
TR Transparency
DS darkness of sky
B30 8x30 binoculars
B50 7..12x50 binoculars
Weather conditions
u some clouds U a lot of clouds f fatigue
b somebit bright sky B quite bright sky M moon
Rec-Corrected and athmospheric extinction corrected magnitudes
were used for magnitude calculations
;-------------------------------------------------------------------
; ZETAAUR.MAG+LOG
;-------------------------------------------------------------------
; mag Ra Dec remark B-V Tyc rc Hipnumber warning
;-------------------------------------------------------------------
v -9 5.0229 +41.0433 ; HIP-rc BV+1.154 376 399 HIP23453
a 3.93 5.5932 +54.1703 ; BV+1.010 373 393 HIP28358 *mult
b 3.87 3.4512 +42.3443 ; BV+0.425 378 387 HIP17529
c 3.86 3.4419 +32.1718 ; HIP v BV+0.022 386 386 HIP17448 ***mult,var
d 4.01 4.0840 +47.4245 ; Tyc W BV-0.025 401 401 HIP19343 **var
e 4.20 5.5129 +39.0855 ; BV+1.132 397 420 HIP27363 *mult
f 4.06 3.3858 +35.4728 ; Tyc W BV+0.029 405 406 HIP18614 **var
g 4.17 3.0904 +49.3648 ; BV+0.595 405 417 HIP14632
h 4.48 4.3651 +41.1533 ; BV+1.171 425 448 HIP21476
i 4.34 4.1454 +48.2434 ; Tyc W BV+0.935 415 434 HIP19812 **var
j 4.28 4.0625 +50.2105 ; Tyc U BV-0.011 428 428 HIP19167 **var
k 4.53 6.1523 +29.2953 ; Tyc W BV+1.021 433 453 HIP29696 **var
n 4.71 5.4910 +39.1052 ; BV+0.949 452 471 HIP27483
o 4.46 4.5717 +53.4508 ; BV-0.017 446 446 HIP23040
p 4.79 5.1811 +33.2218 ; BV+1.252 454 479 HIP24727
;
; Kari Tikkanen observed
--------------------------------
DD MMYYYY UTC MAG OBS
-------------------------------- == in Oulu and Kiuruvesi == by Kari Tikkanen
16 2 2001 18.090 4.06 a 1 v 1 e ; B50 TR,DS good
16 2 2001 18.160 3.82 v 1 a ;u B30
16 2 2001 18.160 3.90 v 3 e ;u B30
16 2 2001 18.160 4.08 b 2 v ;u B30
16 2 2001 18.160 4.05 a 1.3 v ;u B30
16 2 2001 18.160 4.17 f 0.8 v ;u B30
21 2 2001 18.000 3.99 a 1 v 3 e ; B50 TR good
21 2 2001 18.020 4.00 d 0 v 3 h ; B50 "color d3v0h"
25 2 2001 21.410 3.94 a 1 v 3 e ; B50 TR moderate
25 2 2001 21.420 4.08 b 1 v 2.5 h ; B50
1 3 2001 17.495 4.00 a 1 v 2.3 e ; B50 TR moderate poor
1 3 2001 17.505 4.03 b 1 v 3 h ; B50
4 3 2001 20.260 3.88 a 0 v 3 e ;Mu B50 Moon, TR moderate
4 3 2001 20.280 4.01 b 1 v 5 h ;Mu B50
5 3 2001 17.480 3.97 a 0.5 v 2 e ;M B50 Moon, TR moderate good
5 3 2001 17.490 4.06 b 1 v 2.5 h ;M B50
6 3 2001 1.290 3.86 a 1 v 1.4 e ;M B50
6 3 2001 1.310 4.09 b 1 v 3 h ;M B50
7 3 2001 17.082 4.01 a 1 v 2 e ;B B50 Dusk, Tr good
7 3 2001 17.095 3.88 b 0 v 3 h ;B B50
7 3 2001 18.300 3.94 a 1 v 6 e ;M B50 Moon
7 3 2001 18.300 4.08 b 1 v 2.2 h ;M B50
7 3 2001 23.340 3.90 a 1 v 2 e ;M B50
7 3 2001 23.340 4.10 b 1 v 3 h ;M B50
9 3 2001 16.565 4.10 a 3.5 v 2 e ;Bu B50 thin cloud, Tr moderate poor
9 3 2001 16.573 4.04 b 1 v 2.8 h ;Bu B50
16 3 2001 21.220 4.28 b 3 v 2 h ;uf B50
16 3 2001 21.240 4.34 b 2.5 v 1 h ;uf B50
19 3 2001 18.120 4.19 a 5 v 0 e ;B B50 TR good
19 3 2001 18.130 4.32 b 5 v 2 h ;B B50 dusk
21 3 2001 17.540 4.11 a 2.5 v 1 e ;Bu B50 cirrus nearby
21 3 2001 17.550 4.29 b 2 v 1 h ;Bu B50
22 3 2001 18.460 4.12 a 3.5 v 1 e ;b B50 dusk, TR moderate
22 3 2001 18.470 4.26 b 3 v 2 h ;b B50
25 3 2001 19.080 4.09 a 2.3 v 1 e ; B50 TR good !
25 3 2001 19.100 4.27 b 3.3 v 2 h ; B50
26 3 2001 19.270 4.08 a 2 v 1 e ; B50 TR good !
26 3 2001 19.280 4.16 b 3 v 4 h ; B50 and zeta more red than h!
28 3 2001 19.200 4.15 a 4 v 0.5 e ; B50 TR moderate good
28 3 2001 19.210 4.26 b 3 v 2 h ; B50
6 4 2001 18.390 4.08 a 2.2 v 1 e ;B B50 TR good, dusk
6 4 2001 18.400 4.21 b 1 v 1 h ;B B50
6 4 2001 20.310 4.08 a 3 v 1 e ;M B50 was marked "a3v1b"
6 4 2001 20.340 4.25 b 1.2 v 1 h ;M B50
10 4 2001 18.560 4.07 a 2 v 1 e ;B B50 dusk, TR good!
10 4 2001 18.580 4.17 b 3 v 4 h ;B B50 dusk
10 4 2001 20.150 4.17 a 4 v 0 e ;b B50 little dusk
10 4 2001 20.170 4.22 b 5 v 5 h ;b B50
12 4 2001 19.390 4.09 a 3.5 v 1 e ;Ub B50 through clouds, stars foggy
12 4 2001 19.400 4.08 b 1 v 3 h ;Uub B50 more foggy, TR poor
12 4 2001 23.040 4.05 a 4 v 1 e ;u B50 more clear sky
12 4 2001 23.060 4.23 b 1 v 1 h ;u B50
13 4 2001 19.080 4.13 a 3 v 0.5 e ;B B50 dusk, TR good
13 4 2001 19.100 4.19 b 4 v 5 h ;B B50
14 4 2001 0.140 4.08 a 5 v 1 e ;b B50 dawn
14 4 2001 0.150 4.25 b 3 v 2 h ;b B50
14 4 2001 18.590 4.09 a 3 v 1 e ;UB B50 through cirr, fog stars, dusk
15 4 2001 18.590 4.06 a 1.8 v 1 e ;Bu B50 Po= pass clouds
15 4 2001 19.000 4.12 b 1 v 2 h ;BUz B50 unreliable
17 4 2001 0.400 3.98 a 5 v 3 e ;u B50 quite low, some clouds near
17 4 2001 0.420 3.94 b 1 v 5 h ;u B50
17 4 2001 1.020 3.85 a 3 v 4 e ;B B50 Clear sky, dawn
17 4 2001 1.050 3.92 b 1 v 4.5 h ;B B50 low in north
20 4 2001 19.430 3.90 a 1 v 3 e ;B B50 thin cirrus on NW
20 4 2001 19.460 3.86 v 1 b 6 h ;B B50
20 4 2001 21.310 3.90 a 3 v 4 e ;bU B50 thin cirrus, Capella foggy
20 4 2001 21.330 4.06 b 1 v 5 h ;bU B50
21 4 2001 19.530 3.91 a 1.3 v 3 e ;B B50 clear sky, but orange layer
21 4 2001 19.550 3.82 v 1 b 4 h ;B B50
; Veikko M臾elobserved ; == in Helsinki :== by Veikko M臾el19 3 2001 19.250 3.97 b 1 v 4 e ;B B50 by V.M. Aurora
20 3 2001 19.250 3.91 a 3 v 1 b ; by V.M.
23 3 2001 19.100 3.91 a 4 v 2 b ; B50 by V.M. in Hollola
25 3 2001 19.000 3.91 a 8 v 3 b ; by V.M.
10 4 2001 18.550 3.91 a 4 v 2 b ; by V.M.
24 4 2001 20.100 3.90 a 8 v 5 b ;L by V.M. Hki, low, difficult to see
#END
Observations #75
EXTinction Calculated=TRUE
----------------------------------------------------------------------
III Light curve of observations
Light curve of zeta Aurigae
15/16 Feb - 24 Apr 2001
by
members of URSA.VSS
mag
3.8 +------------------------------------------------------------------+
|x x |
| x |
| x x |
3.9 +x x X X +
| * * * * x x *
| x x x |
| x * |
4.0 + X x x +
| x x |
|X x x x x |
|x x x x X x |
4.1 +x x x X x xx X xx +
| xx x |
| x x |
|x x X |
4.2 + x x +
| x x |
| x xx |
| x x x |
4.3 + x x +
| x |
| x |
| |
+----+----+---+---+----+----+----+----+----+-+---+----+----+---+---+
15 20 25 1 5 10 15 20 25 301 5 10 15 20
February | March | April 2001
Explanations
x single obs by Kari Tikkanen URSA.VSS
X two or more obs by Kari Tikkanen URSA.VSS
* observations by Veikko Makela URSA.VSS
---------------------------------------------------------------------
IV Mean light curve
Mean Light curve of zeta Aurigae
15/16 Feb - 24 Apr 2001
by
Kari Tikkanen URSA.VSS
mag
3.8 +------------------------------------------------------------------+
| |
| |
| o |
3.9 + o o +
| |
| o o |
| o o |
4.0 + o o o +
|o o o o o |
| |
| o |
4.1 + o o +
| o o |
| o o |
| o oo |
4.2 + oo o o +
| o |
| |
| o |
4.3 + +
| o |
| |
| |
+----+----+---+---+----+----+----+----+----+-+---+----+----+---+---+
15 20 25 1 5 10 15 20 25 301 5 10 15 20
February | March | April 2001
Explanations
o mean of a-v-e and b-v-h observations by Kari Tikkanen URSA.VSS
---------------------------------------------------------------------
V Minimum calculation and conclusions
Minimum calculation:
I used only my personal observations for minimim calculation.
I used also following assumptions:
- duration of total eclipse 36.8 d,
- duration of partial eclipse 1.4 +- 0.2 d.
(Griffin,R.E.M. et al, Astron.Astrophys. 234,284-298(1990), p.296-297).
I concluded minimum by
1) drawing lines and bisected chords on paper and
2) drawing lines of total and partial eclipse on transpacing paper
that I used as template that I tried to fit in my observations.
Minimum was on about 28 March 2001 09 UTC and error limits
are about +-12 h. GCVS1985 O-C is approx. +0.1 days.
Zeta Aurigae seems to have brightened 0.1 mag in two months.
Minimum was not so flat as drawed in Burnham's Celestial Handbook, but
variable. Minimum was about 0.23 +-0.04 mag deep for my eyes.
minI AURzeta 51996.9 0.5 Geo Tikkanen n=69 (calculated by Tikkanen)
Some remarks:
Due to redness of zeta Aurigae and red-corrected sequence my observations
above gave much lower magnitudes than photovisual magnitudes etc in
literature. My observations above gives range 3.95-4.18 mag
when GCVS gives range 3.70-3.97. It means zeta Aurigae appears to me
normally (outside eclipse) as bright as 3.95 mag blue star.
But if I would "inverse back" my red-correction (B-V=+1.154) then
it would mean decreasing 0.23 from my observations.
This way I'd get range 3.72-3.95 which is in better harmony with GCVS range.
Sequence a-v-e gave 0.1 mag brighter values than b-v-h.
Perhaps a is brighter than b contrary to my rc magnitudes (?).
Skies were not so dark in April there was often dusk. This interference
might explain that discrepancy and also "brightening" of zeta Aurigae.
Anyway in future some other red-sensitive observers might need also some
brighter comp stars than a and b.
Conclusions:
With good luck it is possible even for single observer
to measure zeta Aurigae minimum but uniting observations
from different observers to single proper curve might be hard task
due to red colour of variable and different red-sensitive eyes of observers.
----------------------------------------------------------------------
With Best Regards,
Mr. Kari Tikkanen
member of URSA.VSS
AAVSO.TKK
http://vsnet.student.oulu.fi/~ktikkane/astrov.html
vsnet-adm@kusastro.kyoto-u.ac.jp
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