AAVSO NEWS FLASH No. 18
THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
25 Birch Street, Cambridge, MA 02138 USA
Tel. 617-354-0484 Fax 617-354-0665
INTERNET: aavso@aavso.org
* * * AAVSO NEWS FLASH * * *
Subject: FG Sge, FO Aql, CC Cnc, EM Cyg, No. 18
AH Her, AY Lyr, Markarian 421
May 9, 1996
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FG SAGITTAE
We have been informed by the Central Bureau of Astronomical Telegrams
that S. Shugarov, Sternberg Astronomical Institute, Moscow, reported
that FG Sge, the central star of a planetary nebula, has faded
dramatically to approximately V magnitude 16 and B magnitude 17 on
April 24.04 UT (IAU Circular 6323). Our member Monsignor Ron Royer
has confirmed the fading and his CCD observations made with IR blocking
filter indicated that this star was at magnitude 16.0 on May. 7.3556 UT.
FG Sge started to decline from its about 25-year long average maximum
magnitude of 9.2 in August 1992. By October 1992 it reached magnitude
13.7 (see AAVSO Alert Notice 163). Since then, it has brightened to
magnitude 10.2 several times but has never fully reached maximum, and
has faded, reaching as faint as magnitude 14.4 in August 1994.
Recent observations indicate that in January 1996 it reached 10.2 and
started to fade slowly, as shown by the observations below. The current
magnitude is the faintest FG Sge has been since 1894 (see AAVSO Alert
Notice 163). Recent observations include:
AAVSO Observer
UT JD Mag. Initials
FEB 26.2 2450139.7 10.5 KIS
FEB 27.1875 2450140.6875 10.9 KWO
FEB 29.13 2450142.63 11.9 MPR
MAR 3.16 2450145.66 11.8 MPR
MAR 9.18 2450151.68 11.9 GRL
MAR 21.177 2450163.677 12.4 DPA
MAR 28.1 2450170.6 12.5 SJZ
APR 8.0 2450181.5 13.9 SNO
APR 22.126 2450195.626 14.4: PYG
APR 27.102 2450200.602 14.5: PYG
APR 28.097 2450201.597 14.3: PYG
MAY 5.072 2450208.572 <13.7 PYG
MAY 6.079 2450209.579 <13.7 PYG
MAY 7.3556 2450210.8556 16.0 CCD RR
MAY 8.049 2450211.549 <13.7 PYG
Observers should be aware of the fact that this star has two very close
companions to the east which should not be confused with FG Sge. The closer
of the two is a suspected variable reported by R. Royer to be at magnitude
12.3 on May 7.3556 UT. The second companion was reported by Royer to be at
about 15.0 on May 7.3556 UT.
AAVSO Alert Notice 221 which contains an 'e' scale AAVSO Preliminary
chart and an AAVSO light curve of FG Sge from 1985 to date has been
issued today and has been posted on our ftp site:
ftp.aavso.org(198.116.78.2) in /pub/alert221
and will soon be posted on our web site at the following address:
http://www.aavso.org
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FO AQUILAE
The dwarf nova type (U Gem subclass) cataclysmic variable FO Aql is
brightening as indicated by the following observations:
AAVSO Observer
UT JD Mag. Initials
APR 17.1271 2450190.6271 14.1 BMM
APR 21.1306 2450194.6306 14.1 BMM
APR 22.1201 2450195.6201 14.3: BMM
MAY 9.0535 2450212.5535 13.5 BMM
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CC CANCRI
The dwarf nova type (U Gem subclass) cataclysmic variable CC Cnc is
in outburst as indicated by the following observations:
AAVSO Observer
UT JD Mag. Initials
MAY 7.0743 2450210.5743 14.5 BRJ
MAY 7.1958 2450210.6958 <13.3 BTH
MAY 8.1972 2450211.6972 13.5 BTH
MAY 9.2299 2450212.7299 13.1 BTH
The last outburst of this star began on March 22, 1995 and reached
magnitude 13.2 at maximum on March 25.
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EM CYGNI
The dwarf nova type (Z Cam subclass) cataclysmic variable EM Cyg is in
outburst as indicated by the following observations:
AAVSO Observer
UT JD Mag. Initials
APR 30.1056 2450203.6056 13.6 BMM
APR 30.5097 2450204.0097 13.6 RR
MAY 1.4431 2450204.9431 13.6 DIL
MAY 7.0806 2450210.5806 13.5 BMM
MAY 7.295 2450210.795 13.2 CCDV ZRE
MAY 9.0569 2450212.5569 12.6 BMM
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AH HERCULIS
The dwarf nova type (Z Cam subclass) cataclysmic variable AH Her is in
outburst as indicated by the following observations:
AAVSO Observer
UT JD Mag. Initials
MAY 6.1986 2450209.6986 14.4: HSG
MAY 6.997 2450210.497 12.9 PYG
MAY 7.0708 2450210.5708 13.8 DPL
MAY 7.178 2450210.678 13.40 CCDV ZRE
MAY 7.2299 2450210.7299 12.9 GRI
MAY 7.2535 2450210.7535 13.4 HSG
MAY 7.953 2449845.453 12.8 PYG
MAY 8.2347 2450211.7347 12.9 BTH
MAY 8.990 2450212.49 12.6 DPA
MAY 9.2319 2450212.7319 12.0 HSG
MAY 9.2729 2450212.7729 11.7 BTH
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AY LYRAE
The dwarf nova type (SU UMa subclass) cataclysmic variable is in outburst
as indicated by the following observations:
AAVSO Observer
UT JD Mag. Initials
MAY 1.2521 2450204.7521 <13.6 HSG
MAY 4.994 2450207.494 <14.4 PYG
MAY 6.014 2450209.514 <14.4 PYG
MAY 6.2007 2450209.7007 <14.2 HSG
MAY 7.022 2450210.522 <14.4 PYG
MAY 7.247 2450210.747 18.60 CCDV ZRE
MAY 8.984 2450212.484 13.5 DPA
MAY 9.0174 2450212.5174 14.0 BMM
MAY 9.2389 2450212.7389 13.8 HSG
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MARKARIAN 421
We have been informed by Dr. J. Pesce, at the Space Telescope Science
Institute that the Whipple Gamma Ray Collaboration has reported an
extraordinary outburst of gamma ray activity from the BL Lacertae
type object, Markarian 421 (see AAVSO Alert Notice 220).
An 'e' scale AAVSO preliminary chart of Markarian 421 has been issued with
AAVSO Alert Notice 221 and has also been posted on our ftp site:
ftp.aavso.org(198.116.78.2) in /pub/alert221
and will soon be posted on our web site at the following address:
http://www.aavso.org
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We thank the following contributors for the data that they have provided
for this News Flash:
BMM - M. Biesmans, Belgium KIS - G. Krisch, Germany
BRJ - J. Bortle, USA KWO - W. Kriebel, Germany
BTH - T. Burrows, USA MPR - P. Maurer, Germany
DIL - W. Dillon, USA PYG - G. Poyner, England
DPA - A. Diepvens, Belgium RR - R. Royer, USA
DPL - P. Dombrowski, USA SJZ - J. Speil, Poland
GRI - J. Griese, USA SNO - L. Szentasko, Hungary
GRL - B. Granslo, Norway ZRE - R. Zissell, USA
HSG - G. Hanson, USA
Please monitor these objects closely and phone-in, fax, or e-mail your
observations to the AAVSO.
Good observing!
Janet A. Mattei
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Symbols may include: < = fainter than magnitude given (variable not seen)
: = uncertain
CCDV = Charge-coupled device with (V) filter
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