Peck, Falcke, Henkel et al. 2000: Megamaser in Mrk 348

A Flaring Megamaser in Mrk 348

Alison Peck1, Heino Falcke1, Christian Henkel1, Karl M. Menten1, Yoshiaki Hagiwara1, Jack F. Gallimore2, James S. Ulvestad3

1Max-Planck-Institut für Radioastronomie, Auf den Hüugel 69, D-53121 Bonn, Germany (
2Bucknell University, Lewisburg, PA 17837, USA
3NRAO, P.O. Box 0, Socorro, NM 87801, USA

to appear in: IAU Symp. 206, Cosmic Masers: From Protostars to Black Holes, eds. V. Migenes et al., ASP Conf. Ser.


We report new observations of the H2O megamaser in the Seyfert 2 galaxy Mrk 348. Following our initial detection in 2000 March using the Effelsberg 100 m telescope, re-analysis of previous data on this source indicates that the maser was present but only marginally detectable in late 1997. Monitoring through late 2000 shows that the maser has again decreased to its original level. The H2O line is redshifted by ~130 km s-1 with respect to the systemic velocity, is extremely broad, with a FWHM of 130 km s-1, and has no detectable high velocity components within 1500 km s-1 on either side of the strong line. Followup VLBA observations show that the maser emission emanates entirely from a region <=0.25 pc in extent, toward the base of the radio jet.

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