The SU UMa-type dwarf nova T Leo is undergoing an outburst as reported by R. J. Modic (AAVSO) in [vsnet-obs 5104].
Object YYMMDD.DDD(UT) Mag observer code LEOT 970219.276 12.2 MRV LEOT 970219.347 11.9 MRV
The last outburst of T Leo in the VSNET reports dates back to 1995 May 21, when the star showed a normal outburst reaching mv ~10.
T Leo appears to be in outburst.
T LEO 97 FEB 19.4889 10.9 HSG Seq: AAVSO T LEO 97 FEB 19.5000 10.9 HSG T LEO 97 FEB 19.5250 10.8 HSG T LEO 97 FEB 19.5486 10.7 HSGConfirmative observations would be very appreciated.
T Leo was actually last observed in outburst by P. Schmeer on 1995 Nov. 13 at mv=10.4 (cf. vsnet-alert 272). This outburst was confirmed to be a superoutburst (cf. vsnet-alert 279, L. Szentasko).
Observations to vsnet-obs indicate the dwarf nova T Leo is showing a remarkable re-brightening, a presumable superoutburst triggered by the 'precursor' outburst on Feb. 19. Selected observations since the decline of the first maximum:
YYMMDD(UT) mag code 970220.378 111 MRV 970220.447 111 MRV 970220.485 109 HSG 970220.624 107 Wnt 970220.717 11.25V Kis 970220.828 11.36V Kis 970221.198 118 MRV 970221.485 118 HSG 970221.708 <119 Wnt 970222.239 <129 HSG 970222.581 11.73V Kis 970222.635 <116 Wnt 970222.678 109 Ioh 970222.717 11.09V Kis 970223.180 108 MRV 970223.241 107 MRV
V-band CCD observations by S. Kiyota (vsnet-obs 5127) indicate superhumps probably already appeared during the decline phase of the precursor outburst. The present behavior strong resembles that observed during the initial stage of the 1993 Jan. superoutburst (T. Kato, in preparation).
Light curve of the 1995 May normal outburst (courtesy by AFOEV and VSOLJ):
Light curve of the 1994 April superoutburst (courtesy by AFOEV and VSOLJ):
Superhumps (1993 Jan. superoutburst):
Extracted from old (pre-SN 1993J, pre-VSNET) log archive, recording the 1993 January superoutburst of T Leo. Hope this would be helpful in designing your crucial observations. We are happy to receive your report on successful observations, and far more productive exchange of information on this medium of 4-year's continuous upgrade! (Use vsnet-obs for reporting, vsnet-chat for discussion.) The VSNET manager group will be continuously upgrading the T Leo online information.
From: Patrick Schmeer Date: 1993-01-04 Visual magnitude estimates by P. Schmeer, Bischmisheim, Germany: T LEONIS (UGSU) Jan. 1.166 UT, (13.9 ; 2.124, 10.4 ; 3.119, 10.7 ; 4.130 UT, 10.9 Rare outburst (cf. several IAUCs) Regards, Patrick Schmeer
CCD observations of T Leo on Jan. 2 indicate this star was rapidly fading. The observations were performed from 2.750 to 2.895 UT with the time resolution of 30 s. The sky was very clear and I could cover more than two full orbital cycles of this dwarf nova with typical error of single observations less than 0.01 mag.
During this period, T Leo faded by 0.2 mag. Superimposed were hump features of 0.1 mag with maxima at 2.807 and 2.865 UT. The interval suggests this variation is not caused by superhumps, but by orbital modulation.
Subsequent observation tonight confirms rapid fading. The star looks at about V=11.8 on the TV monitor.
CCD photometry of T Leo was obtained on Jan. 3. Following preliminary results will be interesting to you.
* The mean magnitude was V=11.6 (based on GSC V=11.9 star). * decline by 0.15 mag in 4 hr observation * Hump structures with an amplitude of 0.11 mag persisted. The hump maxima were seen at 3.762, 3.820, and 3.880 UT. The profile resembles superhumps (steeper rise). * The hump maxima are well represented by the following formula. Max UT = 2.806 + 0.05965 E The period is significantly longer (by 1.4%) than the orbital (0.058819) one, but is still different from the previously reported superhump period (0.06411).Regards,
From: Patrick Schmeer Date: 1993-01-06 (updated on Jan. 6) Visual magnitude estimates by P. Schmeer, Bischmisheim, Germany: T LEONIS (UGSU) Jan. 1.166 UT, (13.9 ; 2.124, 10.4 ; 3.119, 10.7 ; 4.130 UT, 10.9 ; 5.137, 10.5 Rather faint superoutburst.
Following preliminary results have been obtained from CCD photometry on Jan. 8. (Ouda station, 60-cm + CCD, V band)
1) Continuatin of the outburst. The mean magnitude is steady at about V=11.0 (based om GSC V=11.9). 2) Detection of definite superhumps. * Hump amplitude was 0.10 mag in V. Steep rise and gradual decline. Secondary humps were not prominent. * Hump maxima occurred at 8.703, 8.769, 8.829, 8.894 UT. The times are well represented by the equation: Max.UT = 8.704 + 0.0633 E The period is 7.6% longer than the orbital one. This period is close to that obtained during Jan. 1987 superoutburst (P=0.06411; Variable Star Bulletin, VSOLJ). The present one is slightly shorter, but this difference is resonably explained by the fact that the present superoutburst is fainter than 1987 one. 3) Connection with Jan. 5 hump features. Although cycle count is ambiguous because of 3-day gap and possible period change, the most probale periods are obtained assuming 45 or 44 superhump cycles between 5.872UT and 8.704UT. Max.UT = 8.704 + 0.06289E (45 cycles) Max.UT = 8.702 + 0.06424E (44 cycles)Regards,
(note added in proof: later analysis has confirmed the period here was an 1-day alias of the true period).
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