[vsnet-alert 747] 1993 Jan. record of T Leo

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

    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.

Regards,
Taichi Kato
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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
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T Leonis

     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.

Regards,
Taichi Kato
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T Leonis

     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,
Taichi Kato
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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.
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T Leonis
    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,
Taichi Kato

(note added in proof: later analysis has confirmed the period here was an
1-day alias of the true period).
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