[vsnet-campaign-v4641sgr 130] Null observation on V4641 Sgr

["Tom Richards" <tom@woodridgeobsy.org>]

G'day all.

I did a time-series on V4641 Sgr at 20s time resolution on 2002-07-12 UT
from 09:49:43 to 16:29:23, with a gap from 13:53:12 to 14:07:24. Total of
1201 frames.

Nothing was observed that exceeded the standard error of the observations,
which was 0.06 mag. More details below. I can forward the rather massive
data file if requested.

Dr Thomas J. Richards, FRAS
Woodridge Observatory
8 Diosma Rd
Eltham, Vic 3095, Australia.
Tel +61(0)3 9431-1072
Fax +61(0)3 9840-1500
www.WoodridgeObsy.org

Details:

2002-07-12
----------
180mm refractor, ST7e CCD
15s exposures, 3x3 binning, temp -28o.
Dark-subtracted & flat-fielded.
Two series for E and W of meridian
Total frames: E: 758, W: 999
Dud frames removed from both, viz frames >443 W as dome slit occulted the
stars.
Frames measured: E: 758, W: 443.
Times covered 2002-07-12 UT:
09:49:43-13:53:12 (=4h 4m 29s)
14:07:24-16:29:23 (=2h 21m 59s)
Total period = 6h 40m 16s
Time resolution = 20s.


AIP processing:
SNR=33, SNR error=0.03 mag.
Aperture radii 3,4,6 px on 3x3 binned images
Ref stars (see AAVSO e chart):
C=90 K=99
Separate test carried out to determine standard error = 0.06 mag on a star
of mag ~ Var.

No activity was observed on the star that significantly exceeded the
standard error.

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