(Outburst CCD image by Kenji Tanabe, VSNET Okayama Station)
1RXPJ113123+4322.5 20030309.92 <140 Scp Henden/Sumner sequence 1RXPJ113123+4322.5 20030313.101 129 ScpThe only previously observed outburst of this SU UMa-type dwarf nova was detected by Pavol Dubovsky on 2002 Mar 5.988 UT at mv=13.5 (vsnet-alert 7221).
Precise astrometry by Hitoshi Yamaoka: R.A. 11h31m22.43s Decl. +43o22'38.5" (J2000.0) (vsnet-alert 7234)
Regards, Patrick
First-ever outburst of 1RXP J113123+4322.5
As reported by Pavol A. Dubovsky, the ROSAT-selected cataclysmic variable 1RXP J113123+4322.5 is undergoing the first-ever secure outburst. This observation confirms the dwarf nova-type nature of this object. Since little is known about this new CV, time-resolved photometry is most urgently requested.
The object is located at: 11h 31m 23s, +43o 22' 37" (J2000.0)Accurate astrometry based on outburst CCD images is also highly desired.
YYYYMMDD(UT) mag observer 20011114.190 <145 (Timo Kinnunen) 20011215.000 <145 (Timo Kinnunen) 20011221.161 <147 (Pavol A. Dubovsky) 20020110.356 <142 (Mike Simonsen) 20020112.364 <142 (Mike Simonsen) 20020119.000 <144 (Pavol A. Dubovsky) 20020122.347 <142 (Mike Simonsen) 20020126.374 <142 (Mike Simonsen) 20020203.926 <146 (Pavol A. Dubovsky) 20020204.865 <146 (Pavol A. Dubovsky) 20020205.885 <146 (Pavol A. Dubovsky) 20020208.301 <146 (Mike Simonsen) 20020215.069 <146 (Pavol A. Dubovsky) 20020216.014 <146 (Pavol A. Dubovsky) 20020216.901 <148 (Pavol A. Dubovsky) 20020218.269 <146 (Mike Simonsen) 20020223.318 <146 (Mike Simonsen) 20020305.988 135 (Pavol A. Dubovsky) Regards, Taichi Kato VSNET Collaboration team(vsnet-alert 7222)
I just confirmed this outburst visually using 37cm reflector at 172x. Comps were GSC1.2 301501361 (mag 12.84) and GSC1.2 301501602 (mag 13.13).
1RXP J113123+4322.5 20020306.4354 12.9 LMKNote, the GSC1.2 stars in this vicinity are about 0.15 mag brighter than the Tycho2 Vt, so the "true" brightness is likely around 13.0-13.1
Mike Linnolt Honolulu, HI(vsnet-alert 7224)
I measured 1RXP J113123+4322.5 on 6.160 March 2002 UT at V = 13.45 +/- 0.06. The equipment used was a 0.2 m SCT + ST-8 CCD + V filter. The comparison stars used were GSC 3015:1120 and GSC 3015:1485.
Since I was not aware of a photometric sequence for this star, I measured the following stars diffe rentially with respect to SAO 43786, V = 6.67, B-V = 0.91. These magnitudes have not been correcte d for color differences and the error reflect this.
GSC 3015:1662 V = 12.29 +/- 0.06 GSC 3015:1602 V = 13.07 +/- 0.07 GSC 3015:1485 V = 12.50 +/- 0.06 GSC 3015:1120 V = 11.84 +/- 0.06The position of 1RXP J113123+4322.5 was measured to be 11 31 22.09 +43 22 36.1 +/- 0.5". This position is based on a plate solution using 14 GSC 1.1 stars. Both the photometry and astrometry is a combination of the star under study and a faint companion that is at a separation of 5.14" and a po sition angle of 347 degrees. This measurement is based on a POSS II DSS2/STS cl J(Blue) epoch 1990.001 plate. I estimate the fainter companion to be 2-3 magnitudes fainter than 1RXP J113123+4322.5 in the quiescent state.
An image of the field is available upon request.
If the variable is the southeastern of the pair, then it is identifiable in the 2MASS catalogue at: 11 31 22.54 +43 22 33.3 (2000, uncertainty ~0".2). The J-K color is 0.75 (fairly red), with K=12.65. This is presumably the signature of the cool companion, the J-K color implying a K5/M0 dwarf--- about what you expect.
The companion is at 5".4 (2MASS), with K=14.8 and J-K=0.6. This star is shown in GSC-2.2 with photo-blue mag 17.9. If the J-K color is accurate, then one would expect V ~17.0 for this star; the J-K color is consistent with an early-K dwarf, probably unrelated to the CV.
\Brian
1RXP J113123+4322.5: new SU UMa-type dwarf nova!
Dear Colleagues,
The Kyoto team (R. Ishioka and M. Uemura) observed this outburst last night. The data very clearly show the presence of 0.3 mag superhumps! The star is thus confirmed to be an SU UMa-type dwarf nova. Given the red color of the suggested quiescent object, it is most likely that the "red" object is a chance coincidence of a field star. Further information will be provided by Uemura-san and Ishioka-san.
More observations are most urgently requested!!
Regards, Taichi Kato VSNET Collaboration team(vsnet-alert 7229)
Subject: 1RXP J113123+4322.5: a quiescent counterpart
Examining the Pejcha's image (vsnet-campaign-dn 2150) and the Kyoto images (vsnet-alert 7228), it is revealed that the outbursting object is the northern star of the pair, not the southern star as suggested on vsnet-alert 7224. The precise astrometry with Kyoto images is in progress.
Checking the DSS images, this northern star is rather blue, besides the southern star is red (vsnet-alert 7225). The northern one (2MASS position = 11:31:22.39, +43:22:38.4) is likely a quiesient counterpart of 1RXP J113123+4322.5.
Sincerely Yours, Hitoshi Yamaoka, Kyushu Univ., Japan yamaoka@rc.kyushu-u.ac.jp(vsnet-alert 7230)
1RXP J113123+4322.5 superhump period
J. Pietz has kindly sent his time-series data to us. Thanks very much for your collaboration, Jochen! Using combined data with the Kyoto observation, we performed period analysis and obtained the best period to be 0.06495(2) d.
The observation by J. Pietz were performed about one day after the Kyoto run on March 6. Compared with these observations, superhumps decreased in amplitude from 0.3mag to 0.2mag.
Regards, Makoto Uemura on behalf of VSNET collaboration team(vsnet-alert 7232)
The superhump period is a relatively short one (close to those of UV Per, TV Crv, EK TrA, OY Car, VY Aqr), many of which show relatively infrequent outbursts and large outburst amplitudes. Accurate identification of the quiescent counterpart and accurate measurement of the outburst amplitude are therefore very important.
However, the early appearance (as judged from the comparison with the visual light curve) of genuine superhumps looks somewhat unusual for a short-period system, which usually shows a delay of 2-3 day before the full growth of superhumps.
Another possibility may arise, considering the known clustering of superhump periods of ER UMa stars around this period. ER UMa stars are known to show very quick development of transient large-amplitude superhumps during the earliest stage of superoutbursts (cf. Kato et al. 1996, PASJ 48, L5). The present phenomenon observed in 1RXP J113123+4322.5 may be somehow related to early-stage superhumps in ER UMa stars. Since these superhumps are known to quickly decay in ER UMa stars, further detailed (dense) observations are strongly encouraged. This star is selected as the top-priority midnight target for northern VSNET campaigners.
Please remind to send your observations to Uemura-san and Ishioka-san uemura@kusastro.kyoto-u.ac.jp and ishioka@kusastro.kyoto-u.ac.jp in order to assure a quick analysis.
Regards, Taichi Kato VSNET Collaboration team(vsnet-alert 7234)
The precise astrometry supports this identification.
1RXP_J113123+4322.5 11:31:22.426 +43:22:38.51 (fitting sigma 0".6)
cf. The position of the northern star:
2MASS 11:31:22.39 +43:22:38.4
GSC2.2 11:31:22.423 +43:22:38.11
The DSS1 R image and the Kyoto image, both superimposed by the
GSC-2.2 star marks, are able to be seen:
Sincerely Yours, Hitoshi Yamaoka, Kyushu Univ., Japan yamaoka@rc.kyushu-u.ac.jp
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