Very rare outburst of the symbiotic variable AG Peg

PTS

AAVSO Alert Notice 521

June 23, 2015

Very rare outburst of the symbiotic variable AG Peg

The symbiotic variable AG Peg is in outburst, the firstone observed since its only known outburst, which occurred in 1860-1870.Currently at visual/V magnitude 7.2 (B=7.8), it is an excellent target forvisual, PEP, CCD, and DSLR observers and spectroscopists. The current outburstbegan after 2015 May 27 UT (T. Markham, Leek, Staffordshire, England, from theBAAVSS online

database) and was underway by June 13.90 (A. Kosa-Kiss,Salonta, Romania).

AG Peg has a very interesting history. Regarding the1860-1870 outburst, data collected by E. Zinner (Merrill, 1959, S&T, 18, 9,

490) show AG Peg slowly brightening from visual magnitude~9.2 in

~1821 to ~8.0 in ~1855, then at ~6.2 in ~1860 andbrightening to

6.0 in ~1870, then in decline at ~6.8 by ~1903, andcontinuing to decline slowly (~6.9 in ~1907, ~8.0 in ~1920, ~8.3 in ~1940).

Observations in the AAVSO International Database sinceJuly 1941 show that the decline has continued without interruption from anaverage magnitude of 7.7 to an average magnitude of 8.8-9.0 by mid-January2015. The AAVSO data since 1941 also show the periodic ~0.4-magnitudevariations (~825 days) that have been present since the 1920s.

Thus, after taking about 10 years to brighten from itsminimum magnitude of about 9 to its maximum magnitude of 6.0, and then fadinggradually over 140-145 years, AG Peg is now in outburst again.

There are no observations of the 1860-1870 outburst thatshow the outburst's beginning. This time, however, in 2015, the opportunity ishere to follow the outburst itself closely and learn just what this system doesduring outburst. Observations in all bands and visual observations are stronglyencouraged. AG Peg is bright enough to be a very good PEP target. Forspectroscopists, AG Peg has an extremely complex spectrum that undergoessubstantial changes and would make a very interesting target.

Observations reported to the AAVSO include:

- Visual and untransformed CCD:

2015 Jan 6.773 UT, 8.7 (PYG, G. Poyner, Birmingham,England); 9.78, 9.3 (PUJ, F. Pujol-Clapes, Madrid, Spain); 16.773, 8.8(Poyner); 18.76, 8.60 (PGRA, P. Grocaut, Pallud, France); Apr. 21.1132, 9.0(KWO, W. Kriebel, Schierling/Walkenstetten, Germany); Jun 13.90, 7.7 (KOS, A.Kosa-Kiss, Salonta, Romania); 14.29375, 7.9 (ONJ, J. O'Neill, Topsfield, MA);15.219, 7.7 (SEDB, E. Sawyer, Chicoutimi, QC, Canada); 17.0979, 7.4 (GZN, A.Glez-Herrera, Ferrol, Spain); 21.8109, 7.24(01) V (untransformed) (OCN, S.O'Connor, St. George, Bermuda); 21.946528, 7.4 (SSW, S. Swierczynski, Dobczyce,Poland); 21.9514, 7.2 (KBA, B. Kubiak, Ostrow Wielkopolski, Poland); 22.00208,7.5 (BADA, A. Bielawny, Walbrzych, Poland); 22.00764, 7.4 (SPK, P. Schmeer,Bischmisheim, Germmany); 22.0347, 7.3 (DXAA, X. Domingo Martinez, Lleida,Spain); 22.057, 7.4 (Poyner); 22.2, 7.3 (BRJ, J. Bortle, Stormville, NY);22.7284, 7.27(02) V (O'Connor); 22.8921, 7.4 HEN, C. Henshaw, Bowdon, Cheshire, England, via baavss-alert); 23.2, 7.2(Bortle);

- Transformed PEP (PGD, G. Persha, Lowell, MI):

Jun 22.2114, 7.264(010) V; 22.2245, 7.285(007) V;22.2114, 7.855(023) B; 22.2245, 7.860(015) B;

- Transformed CCD (AAVSOnet BSM camera, reduced andsubmitted by A. Henden, Center Harbor, NH):

V data:

2014 Dec 31.94540, 8.877(013);

2105 Jan 1.95077, 8.932(006);

2.95145, 8.911(007);

5.95246, 8.920(007);

Apr 12.38419, 8.551(0.009);

18.37638, 8.531(008);

May 14.33688, 8.463(005);

15.33729, 8.459(007);

21.32786, 8.431(006);

23.31938, 8.424(007);

24.32849, 8.434(007);

Jun 14.30844, 7.803(005);

B data:

2104 Dec 31.94540, 10.074(025);

2015Jan 1.95077, 10.015(013);

2.95145, 10.030(012);

5.95246, 9.976(011);

Apr 12.38419, 9.590(016);

18.37638, 9.580(017);

May 14.33688, 9.635(013);

15.33729, 9.602(017);

21.32786, 9.587(017);

23.31938, 9.646(030);

24.32849, 9.563(016);

Jun 14.30844, 8.581(009);

Visual observations in the BAA,VSS database by J. Toone(TOO, Shrewsbury, Shropshire, England) and T. Markham (MTON, Leek,Staffordshire, England) indicate AG Peg was not in outburst from late Aprilthrough May 27.

Coordinates: 21 51 01.98 +12 37 32.1  (J2000.0)

Charts with comparison star sequence for AG Peg may becreated using the AAVSO Variable Star Plotter (VSP, http::www.aavso.org/vsp).

A photometry table containing multicolor magnitudes ofcomparison stars may also be obtained via VSP.

Please report observations to the AAVSO InternationalDatabase using the name AG PEG. Be sure to include error values and comparisonstar information.

This AAVSO Alert Notice was compiled by Elizabeth O.Waagen.