RXTE/PCA and Swift/XRT non detection of IGR J19112+1358

ATel #1554; J. Rodriguez (CEA/AIM, Fra.), J. Tomsick (SSL/UC Berkeley, USA), V. Beckmann (ISDC, Switz.), S. Chaty, S. Corbel (CEA/AIM, Fra.), A. Paizis (IASF, Milano, Ita.), S. E. Shaw (University of Southampton, U. K.)
on 3 Jun 2008; 08:47 UT
Credential Certification: Jerome Rodriguez (jrodriguez@cea.fr)

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IGR J19112+1358 was discovered by INTEGRAL in observations of GRS 1915+105 performed on April 24, 2008 (ATel #1489). Soon after we triggered our simultaneous RXTE and Swift follow-up programs.

RXTE observations were performed on Apr. 29 and Apr. 30 for exposures of ~2800 s and ~3422 s respectively.
Swift observations were performed on April 25, 29, and 30 for XRT exposures of ~2000s, ~2700s, and 4000s.
The RXTE pointings were partly simultaneous with the Swift ones.

The source is not detected by any of the two satellites. The 2-60 keV RXTE count rate from the top layer of PCA/PCU2 is compatible with pure background, with a net average count rate of 1.1 ±1.1 cts/s.

We summed the 3 XRT images and estimated a 3-sigma upper limit of 1.7e-3 cts/s from a circular region of 20 arcsec radius. Assuming an absorbed power law, with Nh=8e21 cm-2 (the value of the Galactic absorption in the direction of the source) and two extremes values of the power law photon index (1.0 and 3.2, the latter is the value returned from the INTEGRAL spectrum at the time of the detection, ATel #1489), this translates to a 0.5-10 keV 3-sigma upper limit absorbed flux of 6-17 10^-14 erg/s/cm2. Given the non-detection of this source no further conclusions can be given on the nature of this object (or its genuineness).

We would like to warmly thank the RXTE and Swift planners, and C. Pagani, J. Swank, N. Gerehls for having (accepted and) performed these observations in simultaneity.