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[vsolj-alert 198] Rare outburst of PU Per



Rare outburst of PU Per

 アウトバーストのまれなことで知られている矮新星 PU Per が明るいアウトバー
 ストを起こしていることが報告されています(Kinnunen)。等級は14等台です
 が、過去の挙動よりスーパーアウトバーストが期待されます。

 以下、関連する VSNETの記事です。

Date: Sat, 26 Sep 1998 01:36:47 +0300 (EDT)
From: stars@personal.eunet.fi (Timo Kinnunen)
Subject: [vsnet-alert 2234] PU Per, TU Tri

Hello again, I just learned that these two
exhibit RARE outbursts:

PU Per    19980925.871  14.8  OUTBURST
TU Tri    19980925.865  15.1  outburst

Observer Timo Kinnunen (KNN.VSNET)
         Espoo, Finland

Instr.   44.5 cm f/4.5 refl.

From: Taichi Kato <tkato>
Subject: [vsnet-alert 2235] PU Per rare bright outburst

PU Per rare bright outburst

  The suspected SU UMa-type star, PU Per, is reported to be in bright
outburst as reported by Timo Kinnunen.

  Recent observations:

  YYMMDD(UT)   mag  observer
  980919.942  <154  (G. Poyner)
  980920.030  <154  (T. Kinnunen)
  980921.041  <154  (G. Poyner)
  980921.919  <150  (T. Kinnunen)
  980922.880  <150  (T. Kinnunen)
  980924.919  <150  (T. Kinnunen)
  980925.871   148  (T. Kinnunen)

  PU Per was only once reported in outburst in the last four years;
the single outburst in 1995 October (M. Iida) was a faint one (unfiltered
CCD magnitude 16.6).  Time-resolved CCD observation at Ouda Station during
the fade from this outburst suggested the presence of ~0.06 day period.
CCD time-resolved photometry during the current, apparently one of the
brightest, outburst is therefore very strongly encouraged.

  We would be happy to hear any results, either the presence or absence
of superhumps.

Regards,
Taichi Kato

Date: Sat, 26 Sep 1998 10:59:48 +0900 (JST)
From: Taichi Kato <tkato>
Subject: [vsnet-alert 2236] More on PU Per

More on PU Per

On the 1995 October outburst and historical data:

(from vsnet-obs 1338,
  http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/obs01000/msg00338.html)

  PU Per has faded quite rapidly as the following observations indicates.

  mid-UT     V-C   S.D.   N band    V-mag
---------------------------------   -----
951013.714  3.110 0.099  67 V        16.5
951014.624  4.966 0.283   4 V        18.4

  comparison star: 02h41m58s.80 +35o44'13".4 (J2000.0)
                   GSC V=13.5 (13.42 in revised VSNET chart)

  From low-amplitude hump-like features (likely orbital humps during
decline) in Oct. 13 observations, we have estimated a rough period of
0.058 +/- 0.002 day.  If this modulation actually reflects the orbital
motion, this dwarf nova is suspected to be a ultrashort orbital period
SU UMa-type dwarf nova (WZ Sge-like object or extreme TOAD).  The rate
of decline supports this idea.  The second outburst observed in Romano,
Minello (1976, IBVS 1140) can be identified as a superoutburst.

  Historical outbursts by Romano, Minello (1976):

    I max            II max
2440641  [19.1   2441280  [19.0
    644   17.4       295   15.2
    645  [19.0       298   15.2
                     301   16.6
                     303   19.0
                     308  [19.0

  Further close monitoring would be recommended.  One should remember
the present short outburst may trigger a superoutburst as recently
observed in GO Com.  Please continue a close watch.

Regards,
Taichi Kato, Daisaku Nogami & Ouda team

Outburst astrometry:

(from vsnet-obs 1340,
  http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/obs01000/msg00340.html)

   Makoto Iida (VSOLJ) has kindly measured the position of PU Per from
a CCD image taken at Ouda Station.

            R.A. (J2000.0)  Decl.
--------------------------------------------------------------
  PU Per 02h42m16s.14   +35o40'46".4   (present outburst)
         02 42 16       +35 40 29      Downes & Shara (1993)

  reference: 10 GSC stars, mean residual 0".1

More on historical behavior:

(from vsnet-obs 1460,
  http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/obs01000/msg00460.html)

   We have found one more literature on PU Per and PV Per (Busch, H.,
H\"aussler, K., 1979, VSS 9, 125).   Following outbursts were observed
from Sonneberg plate collection.  My comments are added based on recent
classification of these stars as probable SU UMa-type dwarf novae.

PU Per
------

    JD        mag     comment
 2439051.34  [16.0
    9052.36   15.5   superoutburst
    9053.44   16.0
    9056.48   16.0

    9380.56   16.0
    9385.52   14.7   superoutburst lasting at least 10 days
    9386.53   14.7
    9388.49   15.0
    9390.61   15.5

 2441300.23
      - .49   15.6-15.7 (five plates) = identical with the second outburst
    1304.38  [16.0                      by Romano, Minello (1976)
                                        = superoutburst

  From these data, one may conclude:

  1) The shortest recorded interval between superoutbursts is ~330 day.
  2) Normal outbursts seem to be rare.  Some may be missed due to their
     faintness, though.

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