F. J. Marshall and J. G. Jernigan, Massachusetts Institute of Technology, report the detection of x-ray emission from a region of radius 40" (90-percent confidence) that contains the BL-Lac object Mk 421, a proposed optical counterpart of 2A 1102+384 (Ricketts et al. 1976, Nature 259, 546). The region was observed with the SAS3 rmc from Apr. 27.4 to May 1.5 UT. The flux density of the source was 1.3 ~ 0.3 x 10**-11 erg cm**-2 s**-1 (2-6 keV), corresponding to an x-ray luminosity of 5 x 10**43 erg s**-1 at a redshift distance of 180 Mpc. These measurements also support the possibility that Mk 421 is the source of recently discovered soft x-ray (0.1-0.28 keV) emission from a region containing 2A 1102-384 (IAUC 3212, where at the end of the tenth line Apr. 25.27 should read Apr. 25.7).
International Astronomical Union Circular
- Pub Date:
- May 1978