AAS 200th meeting, Albuquerque, NM, June 2002
Session 78. ISM, SNR, AGB and PNe
Oral, Thursday, June 6, 2002, 10:00-11:30am, Ballroom B

## [78.03] The Sizes of OH (1720 MHz) Supernova Remnant Masers: MERLIN and VLBA Observations of IC 443

I. M. Hoffman (NRAO/UNM), W. M. Goss, C. L. Brogan, M. J Claussen (NRAO), A. M. S. Richards (NRAL/JBO)

New MERLIN and VLBA observations of the 1720 MHz maser emission from the OH molecule in the supernova remnant IC 443 are presented. MERLIN resolved the emission regions showing imaged sizes of 90 < \theta < 180 mas. VLBA images show emission from cores 15 < \theta < 55 mas. These sizes are in rough agreement with theory. We observe the brightness temperatures of the MERLIN peaks to range 1.8 \times 106\,{\rm K} < Tb < 34 \times 106\,{\rm K} and the VLBA peaks to range 4.7 \times 108\,{\rm K} < Tb < 19 \times 108\,{\rm K}. Unlike the Zeeman Stokes V profiles seen in other OH (1720 MHz) SNR masers, we observe symmetrical circular polarization line profiles on all angular scales from 1000 to 10 mas resolution. And, for one component, we observe the maser line width to be 240±0 m/s while the estimated Doppler width is 490 m/s. We interpret this narrow line as being emitted from a spherical region of masing gas.

IMH was supported in part by the NRAO summer student program and the NRAO pre-doctoral researcher program. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under a cooperative agreement by Associated Universities, Inc.

Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.