[vsnet-alert 7340] V4641 SGR brightens and widens range

[Michael Linnolt <linnolt@hawaii.edu>]

I observed this amazing object again this evening, and noticed it has
brightened significantly over past 24 hours. In addition, the chaotic
ultra-short variations in brightness seems to have increased its range to
>0.5 mag compared to ~0.4 yesterday. The periodicity remains on the
order of a second to a few seconds, but the mean brightness tends toward
mag 12.0, on the higher end of the range 12.5-11.8: which I observed in
15mins of continuous visual monitoring between 20020522.4097 and
20020522.4201

The following observations are just representative points, the actual
variations occur at an unprecedented rate for even 4 decimal CV reporting.

SGRV4641 20020522.4132 11.8: LMK
SGRV4641 20020522.4133 12.3 LMK

Note that visual observation or video recording is the only way to monitor
the full range of the brightness variations. CCD would be limited by the
integration times and thus yield only a mean value, unless one has
sufficient aperture to do sub-second integrations.

Mike Linnolt
Honolulu, HI

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp