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Date: Tue, 9 Feb 1993 23:44:26 +0100
From: granslo@argo.uio.no
Subject: CCD Photometry of IP Pegasi
CCD PHOTOMETRY OF THE DWARF NOVA IP PEGASI
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K. Helbak (Slependen, Norway) has reported the following CCD photometry
of this system using a 20.3-cm SCT and the SBIG ST-4 CCD camera:
NO YYYY MM DD.DDDD COMP-VAR MAGN NO YYYY MM DD.DDDD COMP-VAR MAGN
1 1993 01 30.7247 -1.61 12.1 21 1993 02 05.7426 -3.70 14.2
2 1993 01 30.7198 -1.59 12.1 22 1993 02 05.7440 -3.72 14.2
3 1993 02 01.7545 -2.15 12.7 23 1993 02 05.7457 -3.90 14.4
4 1993 02 01.7558 -2.13 12.6 24 1993 02 05.7474 -3.36 13.9
5 1993 02 01.7569 -1.89 12.4 25 1993 02 05.7488 -3.62 14.1
6 1993 02 01.7600 -1.80 12.3 26 1993 02 05.7501 -3.32 13.8
7 1993 02 01.7614 -2.17 12.7 27 1993 02 05.7515 -3.38 13.9
8 1993 02 01.7627 -2.05 12.6 28 1993 02 05.7528 -3.62 14.1
9 1993 02 05.7157 -2.73 13.2 29 1993 02 05.7542 -3.25 13.8
10 1993 02 05.7198 -2.88 13.4 30 1993 02 05.7556 -3.26 13.8
11 1993 02 05.7215 -2.73 13.2 31 1993 02 05.7692 -3.16 13.7
12 1993 02 05.7229 -2.90 13.4 32 1993 02 05.7881 -3.08 13.6
13 1993 02 05.7243 -2.79 13.3 33 1993 02 05.7608 -2.95 13.5
14 1993 02 05.7275 -3.43 13.9 34 1993 02 05.7621 -2.88 13.4
15 1993 02 05.7290 -3.56 14.1 35 1993 02 05.7640 -2.81 13.3
16 1993 02 05.7329 -3.97 14.5 36 1993 02 05.7654 -2.92 13.4
17 1993 02 05.7370 -3.53 14.0 37 1993 02 05.7669 -2.79 13.3
18 1993 02 05.7384 -3.98 14.5 38 1993 02 05.7683 -2.77 13.3
19 1993 02 05.7399 -3.82 14.3 39 1993 02 06.7256 -3.75 14.3
20 1993 02 05.7413 -3.52 14.0 40 1993 02 07.7361 -4.99 15.5
Times are in Universal Time (it was not stated wether the timings refer
to the beginning or the middle of the exposure). The integration time
was 90 seconds. VAR-COMP is the differential magnitude (variable minus
comparison star) and MAGN is magnitude of variable using an adopted
magnitude of 10.5 for the comparison (visual AAVSO magnitude). Measure-
ments are in the instrumental system (no filters have been used). This
spectral response resembles the R band in the UBVRI system. A prelimi-
nary correction for extinction has been applied.
The coordinates for IP Pegasi is RA = 23h 23m.16, Dec = +18 deg. 25'.2
(epoch J2000.0), while the comparison star is located about 30" east of
the variable.
Observer:
Knut Helbak, Sisyfos Observatory, Reverudaasen 102 A, N-1312 Slependen.
- - -
These results indicate that the variable was detected near maximum on
1993 January 30. Thereafter it faded, and the star had nearly returned
to its normal brightness by Febrary 7.
A series of images were taken on the evening of February 5, covering a
time interval of 75 minutes, and an eclipse was probably detected
around Feb. 5.735 U.T. The light curve appeared asymmetric, where the
fading was considerably more rapid than the subsequent brightening.
There was a considerable amount of scatter in the data (amounting to
several tenths of a magnitude), especially when the variable was
faint. This was due to a low signal to noise ratio, with a resulting
poor photon statistic.
It should be interesting to compare these results with other observa-
tions during this and previous outbursts.
Bjorn H. Granslo
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Bjorn Haakon Granslo Tel: + 47 22 85 65 16
Astrofysisk institutt Fax: + 47 22 86 65 05
Postboks 1029, Blindern Internet: granslo@argo.uio.no
N-0315 Oslo, Norway SPAN: ARGO::GRANSLO
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