CVnet - Cataclysmic Variables Network


AAVSO Alert Notice 720: Photometry requested for SS Cygni
13 September 2020


Dr. Mariko Kimura (RIKEN, Japan) requests AAVSO assistance in obtaining V and Rc photometry of the cataclysmic variable SS Cyg in support of an orbital period study.

Dr. Kimura writes: "The X-ray flux of SS Cyg is now increasing and 10-times larger than usual.  This object is brightest at X-ray wavelengths in these 25 years.  The quiescent level of the optical luminosity is also rising.  I consider that this increase of the optical baseline may be caused by the X-ray irradiation of the outer accretion disk and/or the secondary star.  In this case, we could see the irradiation component of the secondary star becomes dominant in the orbital light curve.  I would like to confirm this hypothesis by intensive filtered optical photometry during the quiescent state.  

"I tried to derive the orbital profile from the data taken by the AAVSO observers during the recent 1 yr, but the data was not enough.  More observations are necessary and V-band or R-band photometry is preferable."

Multiple V and Rc CCD and PEP observations per night are requested beginning now. Visual observations (not more than one per night for this campaign) are welcome. The campaign will continue until the SS Cyg X-ray flux has returned to usual levels. The end of the campaign will be announced in the AAVSO forum threads given above; please be sure to subscribe to be kept informed.

As Dr. Kimura mentioned, SS Cyg has also been behaving atypically in the optical over the past several months. Observations in the AAVSO International Database indicate that SS Cyg was at visual magnitude 10.8 on 2020 Sep. 13.28120 UT (G. Sarty, Saskatoon, SK, Canada). SS Cyg has a V range of 7.7–12.4.

Coordinates (J2000): R.A. 21 42 42.79  Dec. +43 35 09.9 (from VSX entry for SS Cyg)

Charts with comparison stars for SS Cyg may be created using the AAVSO Variable Star Plotter (VSP).

Please report all observations to the AAVSO International Database using the name SS CYG.

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









It’s all about the  standstills, those episodes where the star gets stuck at a mid-point between maximum and minimum. If it doesn’t exhibit standstills it isn’t a Z Cam star.










Data from Catalina Real Time Survey 

Drake et al. 2009, ApJ, 696, 87




Northern CVs brighter than 17th magnitude here.

Southern CV's brighter than 17th magnitude here.



ACTIVITY AT A GLANCE

Last updated 07:00 on 23 October 2020

(All objects mentioned in this section are in the International Variable Star Index; additionally, VSX links have been given for selected cataclysmic variables) 

New outbursts and unusual activity reported in the last 72 hours

YYYYMMDD

20201022
IX Dra
V476 Peg
V537 Peg
VW Vul

20201021
SS Aur
WW Cet
ASASSN-17cp
CRTS J081418.9-005022

20201020
SY Cnc
V792 Cyg
V1006 Cyg
LT Eri
NSV 2026
ASASSN-15bu (UGSU, eclipsing, orbital period 0.07681907 d = 110.61946 min)
ASASSN-14ff
CSS J062450.0+503111




Current superoutbursts (since ...)
AY Lac # (20201008, UGWZ, time-resolved photometry is urgently required)
KK Cnc # (20201003, UGWZ)
ASASSN-14en (20201001, UGSU, uperhump period 0.0674(9) d)
V521 Peg  (20200917, UGSU)
ASASSN-14av : (20200917, UGSU:)
 

Z Cam-type dwarf novae at standstill
HL CMa (since 20191106 or earlier)
Z Cam (since 20181012)
V2837 Ori (20191106–20191123; IW And star, eclipsing, Porb= 0.2761069 d)
CK Eri (20190925–20191029, outburst 20191030; IW And star?)
RX And (20190614–20190714)
V507 Cyg (20190403–20190706, IW And star)
AT Cnc (20190212 – 20190603)
1RXS J062954.6-033520 (20190228–20190316)
UY Pup (20181129–20181217)


# indicates a noteworthy or unusual outburst
:  indicates confirmation required
 
'Activity at a Glance' is gleaned from observations reported to AAVSO MyNewsFlash, BAAVSS-Alert, CVnet-Outburst, VSObs-share and VSNET-outburst. We sincerely thank all the observers who contribute timely observations and reports of activity to these email lists.

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