(vsnet-outburst 5856) (vsnet-outburst 5857)
V585 Lyr (formerly TK4 Lyrae) is in outburst-
LYRV585 030914.1076 13.9 SXN BRIGHT OUTBURST LYRV585 030914.1243 13.7 SXN BRIGHT OUTBURSTMike Simonsen
Bright outburst of V585 Lyr
This object is a suspected SU UMa-type dwarf nova. The last reported outburst was on 2001 October 31, reaching mag about 14.0. This outburst was likely a short outburst. The present brightness already surpasses that of the 2001 outburst, and we encourage intensive CCD time-resolved photometry!
Regards, Taichi Kato VSNET Collaboration team
Dear colleagues,
Given the brightness of the current V585 Lyr outburst (vsnet-outburst 5857), and the fact that the UG subclassification of this CV has not yet been firmly established, I decided to start an unfiltered CCD photometry session at CBA Belgium Observatory on Sep 14th, at 18h58m UT. The session lasted for 2.7 hours, and was conducted under very clear skies. I used the 0.35-m f/6.3 telescope and an ST-7 CCD.
I have put the resulting light curve on my web site (www.cbabelgium.com), together with an outburst image. The light curve shows a rather constant object, indicating that the present outburst either is a normal one, or that superhumps have yet to develop. Future will tell ...
Kind regards, Tonny Vanmunster CBA Belgium Observatory www.cbabelgium.com
V585 Lyr: possible presence of superhump-like modulations?
Dear Collagues,
The VSNET Collaboration has just received CCD time-resolved photometry of V585 Lyr by Jochen Pietz (Sep. 14-15). The light curve seems to show 0.1 mag hump-like variations with a period close to 0.1 d. The object was fading at a rate of 0.3 mag/d. If this object is indeed an SU UMa-type dwarf nova, this observations may have recorded the growing stage of superhumps (of a long-period SU UMa-type dwarf nova?). More detailed analysis will be presented later.
Further observations are strongly encouraged!
Regards, Taichi Kato VSNET Collaboration team
Coordinates and Photometry for V585 Lyr.-
Astrometry of V585 Lyr done with CCD images taken by D. Rodriguez (September. 15.873 (UT), with respect to the USNO A2 reference frame (~100 stars, mean residual ~ 0".3)
Software: Astrometrica by Herbert Raab (Austria) R.A. = 19:13:58.43 Decl. = +40:44:09.2 (J2000.0). Observatory: Guadarrama Observatory, IAU station 458 Telescope: 0.20-m f/10 Schmidt-Cassegrain + CCD ST9 Photometry: 14.58 CV, unfiltered CCD observations calibrated on V-magnitude sequence(=CV). Comparison star V 9.28 Tycho catalog GSC 3125 497 Results http://astrosurf.com/blazar/variable/UG03/Variable%20V585Lyr.html Diego Rodriguez M-1 Group
V585 Lyr: continued humps? rare outburst of a long-period system?
Dear Colleagues,
The VSNET Collaboration has further received data from Jochen Pietz. The Kyoto team (observers: R. Ishioka and M. Uemura) and Torii-san (RIKEN) also took the data, part of which has been analyzed. The data seem to show the continued presence of ~0.1 mag humps.
The comment by Jochen Pietz follows:
> Faded by 0.05mag; still no pronounced humps. > If you really want to see any periodic variations, a 0.1176day period > seems to be one possibility.Our own analysis more favors 0.103 d period, although the above period is still perfectly viable. These observations seem to suggest, unless other features appear, that the object can be a long-period (possibly in the period gap?) dwarf nova. Since superhumps in such long-period system can sometimes be less apparent (e.g. TU Men), the low amplitude may be attributable to the weak occurence of tidal instability. Anyway, we need further coverage (hopefully longer than 3 hours per night) of the current rare, long outburst. Further analysis, as well as accurate identification by Yamaoka-san, is in progress.
Regards, Taichi Kato VSNET Collaboration team
Dear colleagues,
Tonight (September 16/17, 2003) is clear again at CBA Belgium Observatory, with much better sky conditions than yesterday. Using the 0.35-m f/6.3 telescope and ST-7 CCD, I performed unfiltered photometry on V585 Lyr for 3 hours AND 46 MINUTES. Similar to the nights before, the light curve (see www.cbabelgium.com) is not showing modulations with an amplitude > 0.1 mag. I used the PDM technique to look for periodicities in tonight's light curve, as well as in the combined light curves, but no significant signal could be detected.
Over the course of tonight's session, V585 Lyr faded by approx. 0.15 mag.
Although there is still a chance that the variable is an SU UMa-type dwarf nova, currently undergoing a normal outburst, the chances are higher that this is a long-period system.
Kind regards, Tonny Vanmunster CBA Belgium Observatory www.cbabelgium.com
Observations for a little over two hours in Tashkent also, based on visual inpsection of light curve, show no evidence of superhumps. Star has faded by 0.1 mag compared to data I took 24 hours ago.
Tom Krajci Tashkent, Uzbekistan
V585 Lyr: Brno observation
Dear Colleagues, We have also received the following report from Rudolf Novak: ===Dear colleagues
I just made more precise analyses of the dataset obtained here in Brno at 14.9.2003. I use 40cm reflector with ST-7 CCD and R filter (from Kron-Cousins). The star was quite bright, since I have no R magnitudes for the field I can't say exact value.
Using comparison star and check stars I got linear profile of variable. Uncertainty of the run was computed as error of linear fit and was equall to 0.04 mag. Comparison star was measured with 0.01 mag uncertainty. Error of variable is same as error computed for another constant star with quite exact same brightness so I suspect that there was no variability at all (more than 0.04mag) in V585 Lyr system. During the run the star was very little brightening.
I include the whole dataset here altogether with deep-field image of the field (combine 490 images, each 30s exposure).
With best regards
Rudolf Novak Copernicus Observatory Brno, Czech Republic
V585 Lyr: emerging superhumps?
Dear Colleagues,
The VSNET Collaboration has received new data from Jochen Pietz. The data now seem to show humps with a larger amplitude. Pietz reported that: "The first data of the current run show 0.3mag humps (first period estimate 0.064 days)". Although this needs to be confirmed by further observation and analysis, the present behavior may be associated with the growing superhumps. The Kyoto team, Hida observatory and Torii-san have been succeeding in obtaining high-quality data, and we can proceed to make a combined analysis. Please observe V585 Lyr and report your observations to vsnet-campaign-report@ooruri.kusastro.kyoto-u.ac.jp !
Regards, Taichi Kato VSNET Collaboration team
Unfiltered CCD time-series observations are ongoing tonight (18/19 Sept) in Tashkent, Uzbekistan. Visual inpsection of the light curve over a span of 80 minutes shows obvious 0.2 magnitude oscillations.
I will send out data in the next several hours when the observing run is finished.
Tom Krajci Tashkent, Uzbekistan
V585 Lyr: definite superoutburst of a new short-period SU UMa star!
Dear Colleagues,
As earlier reported, V585 Lyr now exhibits definte superhumps! A preliminary analysis of the early data yielded a period of 0.0603(3) d. The growth time of the superhumps was determined to be about 3 d, which is compatible with the short superhump period. Upon closer examination of the initial data, there is no clear evidence of early superhumps; the low-amplitude (~0.1 mag) modulations more likely reflected slow modulations (some sort of wave in the disk?). There even seems to be some evidence of super-QPOs in the September 17 data, which are QPOs only observed during the limited stages of a superoutburst (cf. Kato et al. 1992, PASJ 44, L215; Kato 2002, PASJ 54, 87). We seem to have succeeded in covering the most interesting part of the entire outburst light curve! The object seems to bear some resemblance to SW UMa in its outburst properties and superhump profiles.
Although these sets of cicumstantial evidence does not strongly support a system resembling WZ Sge-type object, the short superhump period would surely qualify the object as the most emergent and astrophysically interesting dwarf nova. Please make as long observations as possible, and report your observations to vsnet-campaign-report.
Regards, Taichi Kato VSNET Collaboration team
V585 Lyr: superhump period update
Dear Colleagues,
The VSNET Collaboration has received further data from Arne Henden and Jochen Pietz. The best superhump period determined up to now is 0.06012(4) d. The objects having superhump periods close to this are SW UMa (0.05833 d), V1141 Aql (0.05930 d), WX Cet (0.05949 d), KV Dra (0.06012 d), T Leo (0.0602 d), and EG Cnc (0.06038 d). I presume that all listed objects are familiar to readers :-)
Please keep the current excellent coverage!
Regards, Taichi Kato VSNET Collaboration team
V585 Lyr: further period refinement
Dear Colleagues,
The VSNET Collaboration has received further data from Tom Krajci and Jochen Pietz. The Kyoto team and Torii-san (RIKEN) has almost nightly succeeded in following the object.
The best superhump period up to now is 0.06016(2) d. At this superhump period, many SU UMa-type dwarf novae are known to show period lengthening during the superoutburst plateau. The available data already seem to show some hint of this expected lengthening. Further continous observations are highly wanted to confirm this trend. Please report your observations (including yet unreported ones) to vsnet-campaign-report.
Regards, Taichi Kato VSNET Collaboration team
Two dwarf novae on Moscow Plates
Timo Kinnunen has advised me that IBVS 5058 issues two newly discovered dwarf novae TK4 and TK5.
(2000.0)
TK4 191358.47 +404409.1 14.9-(17.2p UGSU:
TK5 191726.5 +371041 14.3-(17.1p UG P=60:
No ROSAT identifications have been found.
Further monitoring for outbursts is strongly encouraged. Outbursts of these objects will be timely targets of the VSNET collaboration team.
There is some ambiguity on the identification of tk4. I am on travel, but there is a jpeg image available at ftp://ftp.nofs.navy.mil/pub/outgoing/aah/temp/tk4v.jpg which shows the field. One of the two N/S faint stars at the center is tk4; I cannot remember which. That may help you in checking your ID.
Arne
>TK4 is indicated (on IBVS 5058) as the southern one, but it seems to >have moved slightly (1" or more) westward comparing with DSS 2nd >generation images. I will check it with USNO pixel server.I have checked them, but I could not find the firm conclusion about the movement. But on the Arne's jpeg image, the concerning object (the southern one of the N-S double) seems to locate slightly west than on the DSS2 Bj image (1989.504). And, on DSS1 103aO image (1951.670), the concerning object is likely on the same position as on DSS2 Bj.
Could you tell us when the jpeg image was taken, Arne? I guess it can be "the third object" being somewhat bright on Arne's image.
Sincerely Yours, Hitoshi Yamaoka, Kyushu Univ., Japan yamaoka@rc.kyushu-u.ac.jp
Return to Daisaku Nogami's page
Return to HomePage