MAXI J1659-152 has likely returned back into quiescence
ATel #3506; Y. J. Yang, R. Wijnands (University of Amsterdam)
on 22 Jul 2011; 23:06 UT
Credential Certification: Rudy Wijnands (rudy@space.mit.edu)
Subjects: Optical, Ultra-Violet, X-ray, Binary, Black Hole, Transient
We report our most recent Swift observations of the black hole candidate MAXI J1659-152. After the observed re-brightening in May (ATels #3298, #3339, #3379), the source steadily decreased in luminosity.
Our recent three observations taken on 07-15 (~1.3 ks), 07-17 (~0.9 ks), and 07-19 (~1.2 ks) show that the source intensity has dropped significantly, indicating that the source might be quiescent again. However we can not exclude the possibility that the source might re-flare again like what it did earlier. We added three observations together and obtained ~6 source counts (0.3-10 keV, background subtracted). Using small number statistics described in Gehrels 1986 (ApJ, 303:336-346), we obtained a flux upper limit (0.5-10 keV) of 3.0e-13 ergs cm-2 s-1 (assuming a NH of 3e21 cm-2 and a power law model with photon index 2). The luminosity upper limit is 1.8e33 ergs/s (assuming a distance of 7 kpc, Kuulkers et al. 2011) or 0.9-6.3e32 ergs/s (assuming d=1.6-4.2 kpc, ATel #3358).
The source was not detected in all UV/optical bands during all three observations. The obtained upper limits from the last observation are: b >19.34; m2>19.41; u>18.99; v>18.32; w1>19.20 and w2>19.81.
We thank the Swift team for their prompt scheduling of these observations.
