THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
25 Birch Street, Cambridge, MA 02138 USA
BITNET: aavso@cfa SPAN: cfa::aavso
INTERNET: aavso@cfa.harvard.edu
Tel. 617-354-0484 FAX 617-354-0665
AAVSO ALERT NOTICE 207 (May 3, 1995)
FADING OF 2055+43 V1057 CYGNI
J. E. Bortle, Stormville, NY, has informed us that the FU Orionis-type nebular
variable V1057 Cyg has faded abruptly, as indicated by his observations and
those of L. Szentasko, Budapest, Hungary, and T. Vanmunster, Landen, Belgium.
Recent observations received at AAVSO Headquarters include:
Feb 1.0 UT, 12.2, L. Szentasko, Budapest, Hungary; 3.0, 12.1, J. Bortle,
Stormville, NY; 3.0, 12.1, S. Papp, Locsei, Hungary; 8.0, 12.1, Szentasko;
9.1645, 12.0, M. Moeller, Timmendorfer Strand, Germany; 9.7368, 12.0, Moeller;
20.0, 12.2, Szentasko; 24.0, 12.4, Szentasko; Mar. 8.18, 12.4, L. Jensen, Farum,
Denmark; 10.16, 12.3, Jensen; 22.15, 12.3, Jensen; 23.043, 12.8, Vanmunster;
29.12, 12.5, Jensen; 30.12, 12.5, Jensen; Apr 10.01, 12.6, B. Granslo,
Fjellhamar, Norway; 22.04, 13.0, Szentasko; 23.043, 12.8, T. Vanmunster, Landen,
Belgium; 26.3264, 13.0, Bortle; 29.05, 12.8, Szentasko; 29.99, 12.8, Granslo;
30.3521, 12.9, Bortle; 30.98, 12.9, Granslo.
V1057 Cyg has been in the AAVSO observing program since 1971, when it
brightened suddenly to magnitude 9.8; Bortle was the first AAVSO observer to
observe this star, at 9.8 in July 1971. Since then, V1057 Cyg has been very
well monitored. The majority of the observations in the AAVSO International
Database indicate that the star declined slowly from 9.8 to 11.9 by 1983.
Since 1983 it has faded very slowly to an average magnitude of 12.0.
Bortle points out that the recent abrupt fading of this star may indicate a
distinct change in the behavior of V1057 Cyg, and so the star deserves close
monitoring. Accompanying are the "d" and "e" scale AAVSO preliminary charts
of V1057 Cyg that have been prepared by C. Scovil. Observers are strongly
recommended to monitor this star closely, and call in their observations to
AAVSO Headquarters.
ENDING OF THE SUPEROUTBURST OF 1227+14 AL COMAE BERENICES
The superoutburst of this interesting cataclysmic variable has been very well
monitored by observers worldwide. It appears that this rare superoutburst has
now ended, as shown by the observation of D. York, Abiquiu, NM, on May 3.1792 UT
at fainter than 16.0. Accompanying is the light curve of observations of AL Com
received at AAVSO since the start of this superoutburst. Analyzing the data,
we find that from the start of the outburst on 5 April 1995, AL Com declined
to 13.5 in 9 days, at a rate of 0.15 magnitude per day. It was then at
standstill for 5 days at magnitude 13.5. Subsequently, it continued to decline,
from April 19 at 13.5 to April 30 at 15.0, at a rate of 0.13 magnitude per day.
R. Zissell (South Hadley, MA) and G. Walker (Dover, MA) monitored the superhumps
of this cataclysmic variable with CCDs. We analyzed the CCD(V) observations
obtained by Zissell on the nights of April 6, 11, 23, and 25, using the CLEANEST
Fourier Spectrum analysis method developed by Grant Foster at AAVSO Headquarters
(see G. Foster, Astron. Journ. 109, p. 1889, April 1995). We find superhump
periods ranging from 80.4 to 84.7 minutes with a suggestion of the beating of
two close frequencies on April 6 and 11. Particularly from Zissell's CCD(V)
observations, we find that the data on April 6 show superhumps with double-peak
maxima; on April 11 the amplitude of the superhumps has decreased and the light
curve has shifted to double peak minima; on April 23 and 25 the shape of the
superhumps is sinusoidal. We will report on these results at the Scientific
Paper Session during the 84th Spring meeting of the AAVSO.
Checking the 1975 outburst of AL Com, which appears quite similar in behavior
to the current one, the data in the AAVSO International Database indicate that
the outburst started in mid-March and lasted until mid-April. After it faded
to minimum, on June 13 and June 30, 1975, G. Johnson and C. Ford reported the
star at 13.9 and 14.0, respectively, and they both independently indicated that
there was uncertainty in their estimates, without giving specifics of the
uncertainty. These two observations may indicate that AL Com brightened briefly
after it reached minimum. Unfortunately, there are no other observations
between these two "uncertain" observations to confirm the brightening after the
superoutburst of AL Com. Observers are strongly encouraged to continue to
monitor AL Com, as long as possible, to determine its current behavior.
Since the distribution of AAVSO Alert Notice 206, C. Scovil has prepared a
very high-quality finder chart for AL Com which we have, for the first time,
put on an electronic FTP retrieval site. This chart may be retrieved from
cfa.harvard.edu in .TIF, .GIF, and PostScript forms. We are planning to put
more AAVSO charts, as well as other AAVSO materials, on an FTP site, and we
will inform you when and how you may retrieve them.
We sincerely thank the following observers for their close monitoring of AL Com
during this rare superoutburst, and for their contribution to the accompanying
light curve:
M. Adams, Fort Davis, TX; J. Bortle, Stormville, NY; E. Broens, Mol, Belgium;
T. Burrows, Novato, CA; T. Cragg, Coonabarabran, Australia; H. Dahle, Oslo,
Norway; W. Dillon, Missouri City, TX; P. Dombrowski, Glastonbury, CT;
B. Granslo, Fjellhamar, Norway; J. Griese, Rocky Hill, CT; J. Gunther, Stuze,
France; R. Harvan, Leonardstown, MD; G. Hurst, Basingstoke, England;
L. Jensen, Farum, Denmark; J. McKenna, Upper Montclair, NJ; M. Parker, Santa
Barbara, CA; J. Pietz, Erftstadts, Germany; G. Poyner, Birmingham, England;
R. Raphael, S.W. Harbor, ME; R. Royer, Lakewood, CA; P. Schmeer, Bischmisheim,
Germany; C. Stephan, Sebring, FL; R. Stewart, Fairlawn, NJ; L. Szentasko,
Budapest, Hungary; T. Vanmunster, Landen, Belgium; M. Verdenet, Bourbon-Lancy,
France; M. Westlund, Uppsala, Sweden; D. York, Abiquiu, New Mexico.
FADING OF 1904+43 MV LYRAE
The novalike cataclysmic variable MV Lyr, which had been in its bright state at
a mean magnitude of 12.5 since November 1989, has been fading since February,
1995, and is now oscillating at minimum, as indicated by the following
observations:
Feb 1.0, 12.7, L. Szentasko, Budapest, Hungary; 9.147, <12.5, M. Moeller,
Timmendorfer Strand, Germany; 18.182, 12.8, G. Poyner, Birmingham, England;
24.0, 13.0, Szentasko; 28.0, 13.0, Szentasko; Mar 9.1, <14.0, S. Brincat,
Floriana, Malta; 10.116, <13.7, A. Diepvens, Scheps, Belgium; 12.112, 15.3,
Poyner; 12.18, 14.8, M. Verdenet, Bourbon-Lancy, France; 13.17, 14.8, Verdenet;
21.998, <14.2, Diepvens; Apr 22.0138, 16.0, Szentasko; 29.052, 14.0, Szentasko;
May 1.026, 14.5, Poyner; 3.2097, 14.8, D. York, Abiquiu, NM.
Accompanying is an "e" scale AAVSO Preliminary chart of MV Lyr. Please use this
chart in monitoring MV Lyr during its faint state, and report your observations
to AAVSO Headquarters.
ERRATUM
In AAVSO Alert Notice 206, the date of the last minor brightening of GK Per
should have read July 1992. We apologize for this error.
Chart links are obsolete; 11/2013 create charts using VSP at http://www.aavso.org/vsp
The answering machine at AAVSO Headquarters is on nights and weekends for your
convenience. Please call our charge-free number (800-642-3883) to report your
observations. We also encourage observers to send observations by fax at
617-354-0665 or by e-mail through the Internet at aavso@cfa.harvard.edu.
When telephoning in observations, please state the name of the star, the
magnitude, and the time of the observation. The preferred time is either your
local time (be sure to state the time zone and whether it is Standard or
Daylight Savings Time) or Universal Time. You do not need to give the
designation of the star. Please also include the comparison stars you have
used in making the observation.
Many thanks for your efforts and your valuable observations.
Good observing!
Janet A. Mattei
Director
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