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Alert Notice 150: Rare outburst of 2137+48 V1251 Cygni AND Large amplitude HIPPARCOS stars in need of more observations AND Updates on the activities of stars reported in Alert Notice 149

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THE AMERICAN ASSOCATION OF VARIABLE OBSERVERS
25 Birch Street, Cambridge, MA 02138 USA
BITNET: aavso@cfa8 SPAN: nssdca::cfa8::aavso
Tel. 617-354-0484 FAX 617-354-0665

AAVSO ALERT NOTICE 150 (October 31, 1991)

RARE OUTBURST OF 2137+48 V1251 CYGNI

We have been informed by G. Hurst (UK) and P. Schmeer (Germany) that the cataclysmic
variable 2137+48 V1251 Cygni is in outburst, as indicated by the following observations:

Oct. 15.90 UT <14.2 (P. Schmeer)
25.54  12.4  (M. Moriyama, Japan - via T. Kato and Hurst)
26.89  12.4  (Moriyama)
26.833  12.7  (Schmeer)
27.880  12.5  (Schmeer)
29.755  12.6  (Schmeer)
30.06  12.8 (C. Scovil)

This is apparently the fIrst observed outburst since 1963 when it brightened to
photographic magnitude 12.5, as reported by R. Weber (1966) in the Information
Bulletin of Varlable Stars (IBVS) No. 123. This star has been in our program
since the mid-1980's and no outburst observations have been recorded. [subsequently identified as a WZ Sge-type variable]

Please monitor V1251 Cyg closely, using the accompanying chart prepared by C.
Scovil with a CCD (V) sequence obtained by T. Kato of Kyoto University, Japan,
and transmitted to us by P. Schmeer.

LARGE AMPLITUDE HIPPARCOS STARS IN NEED OF MORE OBSERVATIONS

In order for us to provide the data support needed for the observations of long
period variable stars with the HIPPARCOS satellite, the following stars need more
observations at this time:

Desig.       Star       Range               Design.      Star         Range
0004-86    RU Oct  10.2 - <13 P      2018+00    V865 Aql  11.4 - 14.5 P
0024-38A  T Scl       9.2 - 13.0        2022-40     U Mic       8.8 - 14.0
0329-16    RT Eri     8.5 - 12.9 P      2034-29     R Mic       9.2 - 13.4
0413-18    RS Eri    9.2 - <12.8P     2101-24     V Cap      8.2 - 14.4
0445-55    SU Dor   9.3 - 14.5         2116-15     T Cap      9.5 - 13.9
0450-07    SX Eri    9.3 - <13.6       2116-42    W Mic       10.3 - 15.5P
0509-64A   U Dor   9.2 - <15 P        2117-41    V Mic       9.4 - 14.0
0657-66    T Vol     9.7 - <13.9 P     2129+02   WW Aqr   10.5 - 14.5 P
0706-19A  SY CMa 10.4 - 14.3 P      2213-21    X Aqr       8.3 - 14.4
0707+14   VX Gem 10.8 - <15.1 P  2217-22     RT Aqr     8.8 - 13.1
0717+13   V Gem   8.5 - 14.2         2219-38    T Gru       8.6 - 11.5
0721+41   VX Aur  9.6 - <12.5 P     2241-87    RT Oct     10.4 - 14.6 P
0753-43    SU Pup  9.3 - <14.0 P    2245+17    SX Peg     9.7 - 15 P
2011-21    RT Cap  8.9 - 11.7 P      2353-53     Z Phe      10.0 - <15.0 P

Observers worldwide participating in the HIPPARCOS mission are requested
to monitor these stars once a week, if possible, and report the observations
monthly to Headquarters.

The HIPPARCOS mission, in operation for over two years, has been obtaining
valuable astrometric and photometric data on these stars. The visual
observations provided by observers worldwide have been crucial in checking
and refining the ephemerides of these stars used by the satellite. We extend
the appreciation and thanks of the HIPPARCOS Input Catalogue and Science
Teams to all the observers.

UPDATES ON THE ACTIVITIES OF STARS REPORTED IN ALERT NOTICE 149 1825-29 V1017 SAGITTARII

After a short standstill, at around 12.5 magnitude, this symbiotic star is now
slowly brightening as reported by D. Overbeek and D . York. On Oct 26.07 UT it
was 11.5 (York).

1809-29 VZ SAGITTARII

This R Coronae Borealis star undergoing a minimum, after reaching magnitude 12.6 on
Oct. 1.5 UT (T. Cragg), has started to brighten as reported by D. Overbeek, T.
Cragg, and D. York. On Oct 26.07 UT it was 10.9 (York).

V348 SAGITTARII

This interesting variable star has been varying between magnitudes 13.4 and 13.7
as reported by D. Overbeek and D. York.

Clear skies and good observing!

Janet A. Mattei
Director

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