Follow-up radio observations of Nova Mon 2012 at 10 - 142 GHz

ATel #4376; Lars Fuhrmann (MPIfR), Joseph L. Richards (Purdue), U. Bach (MPIfR), T. Hovatta (Caltech), M. Bremer (IRAM Grenoble), I. Nestoras (MPIfR), V. Karamanavis (MPIfR), K. Mooley (Caltech), I. Myserlis (MPIfR), A. C.S. Readhead (Caltech), C. C. Cheung (NRC/NRL), T. Pearson (Caltech), E. Angelakis (MPIfR)
on 15 Sep 2012; 11:32 UT
Credential Certification: Lars Fuhrmann (lfuhrmann@mpifr-bonn.mpg.de)

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Nova Mon 2012 was first detected as a transient gamma-ray source by the Fermi Large Area Telescope on 2012 June 22 (ATel #4224). It was subsequently found to be coincident with an optical nova detected on 2012 August 09 (CBET #3202, ATel #4310). Follow-up optical (ATel #4320), UV and X-Ray (ATel #4321), and radio (ATel #4352) observations have since been reported, as well as a likely progenitor found in archival IR observations from 2004 November (ATel #4365). Here, we report preliminary results of further multifrequency radio and millimeter-wave observations of Nova Mon 2012 made with the OVRO 40m, Effelsberg 100m, and IRAM 30m telescopes, as well as the IRAM Plateau de Bure Interferometer.

The OVRO 40m monitoring at 15 GHz began on 2012 August 20 and the data show an increase in flux density, approximately doubling from (18 +/- 3) mJy at the first epoch to (37 +/- 5) mJy on 2012 September 09. The OVRO 15 GHz data agree well with the 2012 September 01 Karl G. Jansky Very Large Array (VLA) observations reported in ATel #4352. The OVRO flux density scale was derived from daily observations of 3C286, assuming the Baars et al. (1977) value of 3.44 Jy for this source. Quoted errors do not include the approximately 5% overall scale uncertainty. The OVRO 40m data were measured within an ongoing gamma-ray blazar monitoring program and twice-weekly monitoring of Nova Mon 2012 will continue indefinitely.

A two-point spectrum was observed on 2012 September 05 with the Effelsberg 100m telescope recording flux densities of (15.3 +/- 2.6) mJy and (93.7 +/- 1.2) mJy at 10.5 and 32 GHz, respectively, and indicating a highly inverted (approximate nu^+1.6 power law) radio spectrum. Observations of the source with the IRAM 30m telescope on 2012 September 06 yielded flux densities of (452.7 +/- 120.7) mJy and (672.4 +/- 91.8) mJy at 86.2 and 142.3 GHz, respectively. These observations were obtained within an ongoing gamma-ray blazar monitoring program (the F-GAMMA program). The IRAM data points provide evidence of possible spectral flattening toward the millimeter/sub-millimeter range.

An additional observation at 86.7 GHz was obtained with the IRAM Plateau de Bure Interferometer on September 08 revealing a flux density of (329.5 +/- 16.5) mJy.

The obtained quasi-simultaneous spectrum can be accessed here.