(Outburst CCD images by Bernard Heathcote and Tom Richards)
(Wide-field Outburst CCD image by Berto Monard)
NOTE: AD Men was incorrectly identified in the past; A = true AD Men, B is not AD Men
(Outburst CCD images by Bernard Heathcote and Tom Richards)
(Wide-field Outburst CCD image by Berto Monard)
AD Men outburst - observation needed!
As reported by Rod Stubbings, the dwarf nova AD Men is undergoing a bright outburst. This is the first outburst of this star reported to VSNET. The present brightness already surpasses the maximum value in the literature. Since this field is very crowded, the minimum identification may not be certain. We therefore encourage time-resolved photometry (several hours per night) to examine the presence of any modulations. The object is also known as a ROSAT X-ray source.
We would be happy to receive selected CCD images (in FITS format) in outburst. The images will be examined for astrometry and quiescent identification by Yamaoka-san (yamaoka@rc.kyushu-u.ac.jp).
The nominal position in the catalog is 06:04:28.60 -71:25:15.6 (J2000.0)
YYYYMMDD(UT) mag observer 20030304.499 <148 (Rod Stubbings) 20030305.516 <148 (Rod Stubbings) 20030306.483 <148 (Rod Stubbings) 20030312.469 <140 (Rod Stubbings) 20030322.437 <148 (Rod Stubbings) 20030323.467 <150 (Rod Stubbings) 20030324.421 140 (Rod Stubbings) 20030324.433 140 (Rod Stubbings) 20030324.449 140 (Rod Stubbings) 20030324.492 140 (Rod Stubbings) 20030325.433 141 (Rod Stubbings) 20030325.465 141 (Rod Stubbings) Regards, Taichi Kato VSNET Collaboration team
Dear Colleagues,
We have received new data of AD Men from Bernard Heathcote. There was no clear tendency of a fading within the 1.5 d until the last observation (Mar. 29). Although there seems to be modulations, the variation looks more irregular than superhumps. The light curve up to now suggests an SS Cyg-type dwarf nova, although we definitely need more observation (future outbursts) to draw a firm conclusion.
The image has been relayed to Yamaoka-san for accurate identification. The image will be later posted on the VSNET Web.
Regards, Taichi Kato VSNET Collaboration team(vsnet-campaign-dn 3561)
In the ongoing flurry of GRB 030329, I thought I had already reported the observation by Berto Monard. Sorry to Berto! The "1.5-d" mentioned in the previous posting referred to earlier observation by Berto Monard.
A combined analysis of the data did not reveal a definte periodicity, although there is a slight increase of a power around period 0.06 d. The phase-averaged light curve at the period of the strongest power did not reveal the clear presence of superhump-type variations. The upper limit of the superhump-type signal is thus 0.13 mag. Combined with the fading (Rod Stubbings, on March 31), the object is likely an SS Cyg-type dwarf nova, rather than an SU UMa-type dwarf nova.
Regards, Taichi Kato VSNET Collaboration team
Subject: AD Men identification
Originally Tom Richards had questioned about the identification of AD Men on Apr. 6.
>The Downes catalog image of the same field shows a brighter star 13" from >the one it identifies as AD Men, at p.a. 123d. It is not visible on my >image. I wonder if that is AD Men, and Downes has mis-identified it?Today, Berto Monard noticed it independently.
>There is a star 0.2' ESE of AD Men, which seems to vary. In the cv >atlas it is shown bright, but on my 27 March image it is faint and on >the 2 May image it is bright again. This variable is not in UCAC1. >On those dates AD Men itself (at the cv atlas position) was 16.7 and >16.9CR respectively on my images.I have examined the DSS images and found that the ESE star was caught in outburst in the plate taken on 1987 Nov. 28 (R-band) but dim on the plates of other epochs. The object marked on VSNET page/Downes' chart (at the nominal position of AD Men: 06:04:28.60, -71:25:15.6) differs from this outburst object.
Outbursting object on 1987 Nov.;
GSC2.2 06:04:30.836 -71:25:22.25 F=14.80(!) J=18.71 USNO-A2.0 06:04:30.845 -71:25:22.28 r=17.0 b=18.3 = 2RXP J060431.1-712523 (no 2MASS counterpart) The marked object: GSC2.2 06:04:28.526 -71:25:15.26 F=16.62 J=17.66 USNO-A2.0 06:04:28.514 -71:25:15.38 r=16.3 b=17.3 2MASS 06:04:28.69 -71:25:15.4 J=15.333 H=14.923 K=15.036The error circle of X-ray source [HP99] 1272 ( 06:04:30.6 -71:25:29 unc=22" ) contains these two stars, but the former is nearer.
Zwitter and Murani 1995, A&AS, 114, 575 reported a spectrum of "AD Men" at 06:04:28.78, -71:25:56.4 (J2000.0). It was B ~ 14.5, so they thought it to be at outburst. The spectrum shows a blue continuum with hydrogen Balmer absorption lines. But this position is almost identical to the GSC 9172.887 (also cataloged in UCAC1, 2MASS, USNO-A2.0/B1.0, and GSC 2.2). They seem to have observed yet another star about 40" south of the nominal position of AD Men.
Though I cannot access the discovery literature (Hodge and Wright, 1967, "The Large Magellanic Cloud"), I am quite certain that the first star (06:04:30.836 -71:25:22.25) is true "AD Men". The marked object in VSNET page or Downes' online chart shows no significant change among the DSS images, though a slight change is noted by Berto.
Sincerely Yours, Hitoshi Yamaoka, Kyushu Univ., Japan yamaoka@rc.kyushu-u.ac.jp(Note: the cited images have been corrected upon this information. The Downes et al. online edition was updated on 2003 May 9. The above description of the variations may not refer to the correct AD Men).
Return to Daisaku Nogami's page
Return to HomePage