GM Sgr radio update さらに以下の情報が入っています。またIAUCによるとX線ではすでに検出限界以下 になっているようです。 From rhjellmi@zia.aoc.NRAO.EDU Fri Sep 24 06:46 JST 1999 Date: Thu, 23 Sep 1999 15:45:08 -0600 To: dasmith@space.mit.edu, michiel@astro.uva.nl, rpf@astro.uva.nl, rudy@space.mit.edu, gehrels@lheavx.gsfc.nasa.gov, giommi@napa.sdc.asi.it, jem@head-cfa.harvard.edu, lewin@space.mit.edu, rhjellmi@zia.aoc.NRAO.EDU, rr@space.mit.edu, shrader@grossc.gsfc.nasa.gov, stroh@pcasun1.gsfc.nasa.gov, swank@pcasun1.gsfc.nasa.gov, bmg@space.mit.edu, tkato@kusastro.kyoto-u.ac.jp, HARMON@SSLMOR.msfc.nasa.gov, chaswell@star.cpes.susx.ac.uk, ehm@space.mit.edu, Michael.McCollough@msfc.nasa.gov, p.charles1@physics.oxford.ac.uk, eiken@astrosun.tn.cornell.edu, srk@astro.caltech.edu, luisfr@astrosmo.unam.mx, tavani@astro.columbia.edu, ewaltman@rsd.nrl.navy.mil, fghigo@cv3.cv.nrao.edu, rmw@as.arizona.edu, mrupen@zia.aoc.NRAO.EDU, amiodusz@zia.aoc.NRAO.EDU, mirabel@discovery.saclay.cea.fr, S.Chaty@open.ac.uk, greiner@aip.de, mnowak@rocinante.colorado.edu, wheel@alla.as.utexas.edu From: "Robert M. (Bob) Hjellming" <rhjellmi@aoc.nrao.edu> Subject: Update on radio information on GM Sgr Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Length: 2312 Status: O Colloegues, We probably will be sending out something more formal to IAUC or ..., but this is a quick (and cheap) update on information that might affect observing strategies. The last observations of GM Sgr with the VLA on Sept. 23.0 UT, together with the previous data from the VLA, ATCA, and GBI indicate that the radio source has been undergoing an approximately power law decay since going optically thin with a spectral index -0.8 and a power law index -2.1. VLBA observations were made about Sept. 18.0, 20.0, 22.0, and 23.0. It will be next week before we have any idea about what we have from the VLBA because of the time it takes for the tapes to get to the correlator and be correlated. I have made a web page with URL http://vsnet.aoc.nrao.edu/~rhjellmi/gmsgr.html that contains a preliminary image at 4.9 GHz from Sept. 16.02 UT data, and a plot of the abovementioned radio data and approximate power law fits. Work is continuing on the radio imaging at the other VLA epochs; however, there are not enough hours in the day. The double radio source seen Sept. 17.93 UT was mentioned in a previous E-mail. The Sept. 23.0 images show that the only the strong southerly component is still present, ~0.3" south of the Sept. 16.02 location of the strongest radio emission - and the USNO position for GM Sgr. Really good astrometry is critical to deciding whether the true declination of the star is -25 24 25.6 as indicated by the Sept. 16.02 radio centroid and USNO positions, or near -24 24 25.85. It makes a difference between one sided relativistic ejection, and two-sided ejection with one side possibly decelerated while brightening - a la XTE J1748-288. It also may make a difference in whether the motion ends up superluminal or subluminal. In the web page I update what I know about the distance, which indicates a distance between 0.4 and 1 kpc. My own bet/guess is that it will end up near 0.5 kpc because that makes the apparent relativisitic motion closer to what is reasonable for a galactic object. The sky may have many objects with events like these that are missed because of their extremely short duration and unusual characteristics. It is fascinating to see the papers on CVs where GM Sgr appears in tables with the notation "non-cv." Cheers, Bob