Rare outburst of SW UMa
Rare outburst of SW UMa SW UMa is undergoing one of its rare outbursts as indicated by the following observations by L. T. Jensen (vsnet-obs 2562 message).
SW UMA 960411.847 14.0 SW UMA 960411.875 13.5 SW UMA 960411.955 11.7 SW UMA 960411.969 11.4, rapid rise to maximum
The outburst is apparently on its way to maximum. High-speed photometry is therefore highly encouraged, by taking the present first-ever opportunity to cover an entire (super)outburst of this unique dwarf nova. A systematic search for super-QPOs (QPOs with gingantic amplitudes, which probably appear only during the early stage of superoutbursts; cf. Kato et al. 1992 for this particular object: PASJ 44, L215) may be interesting.
SW UMa was last seen in outburst in Aug. 1993. We will keep readers informed via VSNET mailing lists and the VSNET Home Page.
Regards,
Taichi Kato
(vsnet-obs 2570, Taichi Kato)
List of historical outbursts of SW UMa (AN 307 + new data)
date JD observer
1909 Mar 24 Ceraski
1937 Apr 7 2428631 Parenago,Zinner
1939 Nov 17 29585 AAVSO
1942 Jan 17 30377 AAVSO
1943 Jul 30921? Himpel
1943 Dec 14 31073 AAVSO
1945 Mar 7 31522 AAVSO, single obs. 12.5 mv
1946 Feb 1 31853 AAVSO, single obs. 13.6 mv
1947 Mar 12 32257 Beyer,Wellmann
1947 Jul 21 32388 Beyer,Wellmann
1948 Nov 5 32861 Beyer,Wellmann
1950 May 9 33414 Beyer,Wellmann,Sonneberg
1952 Mar 20 34092 Ashbrook,Beyer,Wellmann,Sonneberg
1957 Apr 2 35931 Sonneberg (one day long at 12.4 mp)
1960 Dec 12 37281 Sonneberg
1965 Feb 15 38807 AAVSO,BAA,Sonneberg
1968 Mar 4 39920 AAVSO (not fully confirmed)
1969 Nov 20 40546 AAVSO
1970 Feb 7 40625 AAVSO,Sonneberg
1973 May 24 41831 AAVSO,AFOEV,Sonneberg
1975 Sep 16 42672 AFOEV,Sonneberg
1976 Nov 17 43100 AFOEV
1977 Jan 8 43152 AFOEV, single obs. 12.2 mv
1977 Dec 11 43489 AFOEV,Sonneberg
1979 Feb 23 43928 AFOEV,Sonneberg
1980 Jun 12 44403 AFOEV
1981 Dec 21 44960 AFOEV,BAA,Sonneberg
1986 Mar 3 46493
1990 Mar 14 47965
1991 Feb 25 48313
1992 Mar 3 48685
1993 Feb 17 49036 well-observed normal outburst
1993 Aug 10 49210
(vsnet-obs 2651, Rudolf Novak)
Observer: Rudolf Novak Telescope: Newton 40cm Place: Copernicus Observatory Brno, Czech Republic ---------------------------------------------------
CCD R-band photometry of CVs SW UMa made on 17./18. 04. 1996 at Copernicus Observatory in Brno (Czech Republic) shows superhumps with period P=0.05866d and amplitude about 0.20mag. Error is around 0.04mag for each image. (We have also datas from 17. til 20. 04. 1996 but thay are not reduced yet.)
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Nicholas Copernicus Observatory
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Our observatory... (c) RKN \___________________________________
(vsnet 614, Brian Skiff)
During the recent eruption of SW UMa, I was prompted to get photometry for some of the brighter stars in the field, selected from the (d)-scale AAVSO chart last revised March 1958. The AAVSO sequence has been long known to have inconsistencies (see Hornby 1975, JBAA 85,528).
I observed the stars on two nights (14 April and 1 May 1996 UT) using the Lowell 53cm photometric telescope with a 29-arcsec diaphragm and Stromgren b and y filters. The results for the standard stars are given below along with residuals from the assumed values. Primary standards are marked with an asterisk. The rms residuals are +/- 0.007 for V and +/- 0.004 in b-y. The results for the field stars are listed below. V magnitudes for two bright stars appearing on the chart are quoted from the literature, and for the faintest star, which is close to the dwarf nova, I give the results of Misselt (1996, PASP 108,146). I include the position for SW UMa also, since the one given on the AAVSO chart is in error.
Standard stars
Name V (obs) b-y n resV res(b-y)
HD 42049 5.930 1.049 1 -005 +005
HD 60803* 5.908 0.373 1 +005 -003
HD 64491* 6.234 0.200 1 +004 +004
HD 72779 6.582 0.434 1 +002 -006
HD 73665 6.381 0.600 2 -009 -003
HD 73666 6.616 0.003 2 +006 -002
BD+20 2161 8.815 0.194 2 +005 +002
HD 76151* 6.017 0.407 1 +009 -011
HD 81567 6.004 0.801 1 +007 -002
HD 85217* 6.230 0.308 2 -006 +003
HD 97907 5.317 0.750 1 +009 +001
HD100600* 5.940 -0.072 1 -008 -002
HD101606* 5.736 0.313 1 -009 +001
HD103095* 6.416 0.490 1 -011 +006
HD107168 6.246 0.088 1 -004 +007
HD110184 8.295 0.817 1 -002 -001
HD114092 6.178 0.849 2 +003 +001
HD115256 7.270 0.814 1 +005 -001
Photometry of stars in the field of SW Ursae Majoris
AAVSO Name RA (2000) Dec V b-y n spec
var SW UMa 8 36 42.9 +53 28 37
57 HD 73017 5.66 G8IV = HR3400
65 HD 73131 6.32 K0 = HR3405
87 HD 72522 8 35 46.6 +53 43 33 7.901 0.657 2 K0
.001 .006
-- BD+54 1243 8 35 28.5 +53 42 20 9.576 0.842 2 (k3iii)
.006 .007
100 BD+54 1242 8 34 53.1 +53 37 34 9.877 0.697 2 K2
.008 .013
114 GSC 3797-1376 8 34 44.5 +53 20 05 10.984 0.582 2 (g8iii)
.000 .008
114 GSC 3798-0705 8 36 20.8 +53 37 58 11.409 0.663 2 (k0iii)
.014 .004
123 GSC 3798-0491 8 37 10.8 +53 30 00 12.142 0.608 2 (k0iii)
.002 .007
130 GSC 3798-0530 8 35 58.2 +53 31 42 12.266 0.701 2 (k2iii)
.001 .023
135 GSC 3798-0518 8 36 27.7 +53 17 52 13.51 --- (k5iii) (1)
.03
Note:
(1) V mag. from Misselt (1996, PASP 108,146).
Chartmakers should note in the same field the mag. 12.5 eclipsing variable star EQ UMa = GSC 3798-0625, at 8 36 27.2 +53 34 40 (2000), which was found by deYoung and Schmidt (1992, IBVS 3759). This is not one of the AAVSO sequence stars. Also, the very red mag. ~11 carbon star CGCS 2244 = GSC 3798-0518 = IRAS 08327+5328, at 8 36 27.7 +53 17 52, lies about 11' north of SW UMa. This star is likely to be at least somewhat variable.
\Brian Skiff (bas@lowell.edu)
Correction and addenda to SW UMa comparison stars
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