grs 1915+105 was discovered in aug 1992 with the watch all-sky x-ray monitor on board the granat satellite. the source has been since then one of the brightest objects in the x-ray sky, highly variable in all wavelenghts, from gamma-rays to radio. at a distance of 12 kpc, the absorption towards the source is almost 30 magnitudes, putting the object well beyond the reach of optical telescopes. the uniqueness of grs 1915+105 is that it shows superluminal motion, following a bright radio outburst seen in march 1994 - the first such case in our galaxy. grs 1915+105 is a binary system in which a massive black hole (with perhaps 33 solar mases) is accreting mass from a nearby companion. the companion class is still unclear, but it could be a high-mass object, on the basis of observations performed in aug 1995, that revealed the near-ir reverberation of an energetic radio-outburst. the jet was also observed in the k-band in july 1995. near-ir spectroscopy indicates the presence of strong emission lines (he i 2.06 um and br-gamma 2.16 um) during the high activity periods. grs 1915+105 underwent a new strong outburst in x-rays and radio frequencies in late october 1997. ejection of plasmoids at 0.92 c was also observed at merlin in the radio domain. iso observations, following the too, indicated that the source varies by a factor of 30 (0.5-15 mjy) in the lw3 band on a several day timescale. at that time, when the source displayed a strong x-ray and radio activity, the source flux was much fainter than seen previous- ly at 10 um (what is certainly surprising does not have a good s/n ratio. therefore, and taking into account the strong 10-um variability seen in grs 1915+105, which appears not to follow the near-ir or radio behaviour, we request further monitoring of the source during the last iso observing window (9/3-6/5), beginning on march 16 (rev. 852, not scheduled yet).
Instrument
CAM01
Temporal Coverage
1998-03-28T12:46:05Z/1998-04-04T10:45:21Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, 1999, Too: The Nature Of The Superluminal Galactic Source Grs 1915+105 Iso Monitoring Of The Most Powerful Source In The Galaxy, 1.0, European Space Agency, https://doi.org/10.5270/esa-woogecb
