Superoutburst of V551 Sgr


(Kenji Tanabe's image: V551 Sgr outburst 2003 April)


(Seiichiro Kiyota's image: V551 Sgr outburst 2003 April)


(Roland Santallo's image: V551 Sgr superoutburst 2003 September)

Superoutburst in 2003 September!

(vsnet-alert 7879)

V551 Sgr outburst!

As reported by Rod Stubbings, the suspected SU UMa-type dwarf nova (possibly related to WZ Sge-type objects?) V551 Sgr is undergoing a relatively bright outburst. Urgent time-resolved photomretry is encouraged! The last outburst in 2003 April was a short outburst, well followed by the VSNET team. The last reported long outburst (superoutburst?) occurred in 2001 May; the present brightness already surpasses the reported maximum of the 2001 May outburst! 

Subject: [vsnet-outburst 5894] V551 Sgr outburst

V551 Sgr is in outburst

SGRV551        030920.446   138  Stu.RASNZ 

Regards,
Rod Stubbings

(vsnet-alert 7907)

V551 Sgr: definite superoutburst of a new SU UMa star!

Dear Colleagues,

Roland Santallo (Southern Stars Observatory) has just sent us Sep. 23 observation of V551 Sgr. The object already showed prominent superhumps (amplitude about 0.3 mag). This observation finally confirmed the supposed SU UMa-type nature of V551 Sgr! The superhump period is still rather uncertain (around 0.06 d), but will be readily refined when the baseline coverage is improved. Congratulations, Roland -- this observation finally revealed the long-waited nature of this object, which had been a problem between us since last glimpsed a short outburst early this year! 

Regards,
Taichi Kato
VSNET Collaboration team
(Some progress between these message were omitted; see vsnet-campaign-dn log for the complete history)

(vsnet-campaign-dn 3976)

V551 Sgr: updated superhump period

Dear Colleagues,

The VSNET Collaboration has received new data from Berto Monard (two nights). From the analysis of the combined data, the true superhump period is now established to be 0.06741(3) d. The earlier report corresponded to one of its shorter aliases. The superhump period is comparable to those of rarely outbursting dwarf novae, such as UV Per (0.06641 d), CT Hya (0.06643 d), AK Cnc (0.06749 d). The outburst properties of V551 Sgr seem to be best analogous to these dwarf novae. Further analysis of the entire data is in progress. Please keep observing the current superoutburst! 

Regards,
Taichi Kato
VSNET Collaboration team

Normal outburst in 2003 April

(vsnet-alert 7711)

Rod Stubbings reported an outburst of V551 Sgr [vsnet-outburst 5458]. The last observed outburst was in 2001 May.

***Quotes from VSNET 2001***

V551 Sgr : Long outburst of a WZ Sge candidate in May A. Pearce reported that an outburst of the dwarf nova V551 Sgr occurred in mid-May. The last outburst was in 2000 April. The object has been claimed to be a possible WZ Sge-like object, based on its large outburst amplitude. One the occasion of the 1998 October outburst, G. Garradd obtained time-series photometry on two nights, but the short visibility hindered a firm conclusion on the existence of superhumps (vsnet-campaign 941). The outburst continued relatively long (vsnet-campaign-dn 840, 849, 865, 882). 

Best Regards,
Ryoko Ishioka

---------------------------------------------------
From: "Rod Stubbings" 
Subject: [vsnet-outburst 5458] V551 Sgr outburst
Date: Sun, 27 Apr 2003 02:24:06 +1000

V551 Sgr in outburst

SGRV551        030426.601   144  Stu.RASNZ                          
SGRV551        030426.635   144  Stu.RASNZ

(vsnet-campaign-dn 3598)

V551 Sgr: rapid fading

The object is apparently fading rapidly. The fading has been also observed by the Kyoto observation and observation by Kiyota-san, Tanabe-san and the Okayama U. of Sci. team (the details will follow later). The outburst may have been a normal outburst, or may be a precursor outburst. In the latter case, we may expect a rebrightening. Further monitoring is encouraged. The outburst images have been relayed to Yamaoka-san for astrometry. 

  YYYYMMDD(UT)   mag  observer
  20030327.710  <144  (Rod Stubbings)
  20030330.619  <144  (Rod Stubbings)
  20030331.656  <144  (Rod Stubbings)
  20030402.596  <144  (Rod Stubbings)
  20030404.658  <144  (Rod Stubbings)
  20030405.705  <144  (Rod Stubbings)
  20030406.719  <140  (Rod Stubbings)
  20030409.657  <140  (Rod Stubbings)
  20030424.585  <142  (Rod Stubbings)
  20030425.612  <144  (Rod Stubbings)
  20030426.601   144  (Rod Stubbings)
  20030426.635   144  (Rod Stubbings)
  20030427.582   152: (Rod Stubbings)

Extremely Rapid Fading!!


(Roland Santallo's image on April 29)

The 2001 April Outburst

(vsnet-campaign 941) 

      ****************************************************************
            Rare Outburst of an Large-Amplitude Dwarf Nova
                         V551 Sagittarii
      ****************************************************************
Andrew Pearce (Australia) reports that the dwarf nova V551 Sgr is undergoing a relatively rare outburst. The last outburst was in 2000 April (mv=13.9, Rod Stubbings). The object has been claimed to be a possible WZ Sge-like object (just as AL Com), based on its large outburst amplitude (the minimum reaching the 20th magnitude). One the occasion of the 1998 October outburst, Gordon Garradd obtained time-series photometry on two nights, but the short visibility hindered a firm conclusion on the existence of superhumps. The present outburst, if confirmed, would provide an excellent opportunity to throughly study this still poorly understood dwarf nova. The VSNET Collaboration team lists the object as one of prime targets in the morning sky. 
  YYYYMMDD(UT)   mag  observer
  20010425.603  <140  (R. Stubbings)
  20010426.860  <150  (A. Pearce)
  20010429.613  <140  (R. Stubbings)
  20010429.851  <153  (A. Pearce)
  20010430.581  <140  (R. Stubbings)
  20010430.824  <153  (A. Pearce)
  20010501.608  <140  (R. Stubbings)
  20010502.856  <153  (A. Pearce)
  20010503.828  <153  (A. Pearce)
  20010514.515  <140  (R. Stubbings)
  20010515.574  <140  (R. Stubbings)
  20010522.619  <152  (A. Pearce)
  20010523.821  <152  (A. Pearce)
  20010525.451  <140  (R. Stubbings)
  20010526.833   144  (A. Pearce)

   V551 Sgr is located at: 18h 00m 56s.2, -34o 35' 42" (J2000.0)
Gordon Garradd has kindly provided his CCD image of V551 Sgr taken in 1998 October.


(Gordon Garradd's image: V551 Sgr in outburst) 
Regards,
Taichi Kato
VSNET Collaboration team

The 1997 Outburst

(vsnet-alert 1289)

Rod Stubbings reports the suspected SU UMa-type large-amplitude dwarf nova V551 Sgr is in outburst (vsnet-obs 8052). 

  YYMMDD(UT)   mag  observer
  971023.449  <140  (R. Stubbings)
  971024.494   140  (R. Stubbings)
The quiescence identification being still uncertain, follow-up observations including accurate astrometry are encouraged.

The 1998 Outburst

(vsnet-alert 2266)

V551 Sgr outburst

The dwarf nova V551 Sgr is reported to be undergoing one of its rare outbursts. The supposed quiescent identification suggests a large outburst amplitude (approx. 6 mag). Accurate astrometry and CCD time-series photometry are strongly encouraged. 

  YYMMDD(UT)   mag  observer
  980924.453  <144  (R. Stubbings)
  981010.480   140  (R. Stubbings)
  981010.509   140  (R. Stubbings)

The 2000 April outburst

(vsnet-alert 4596)

The dwarf nova V551 Sgr is undergoing a relatively rare outburst as detailed below: 

SGRV551  20000407.8111  >150  Pea
SGRV551  20000409.8236  138  Pea
SGRV551  20000409.8535  139  Pea

Regards
Andrew Pearce

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