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Intense 1.3-Millimeter Band Emission from 3C454.3

ATEL # 3036; Mark A. Gurwell (Harvard-Smithsonian Center for Astrophysics) & Ann E. Wehrle (Space Science Institute)
on 17 Nov 2010; 17:43 UT
Password Certification: Mark A. Gurwell (

Subjects: Millimeter, Sub-Millimeter, AGN

The Submillimeter Array (SMA) performs ongoing flux density monitoring of quasars that are typically bright in the mm/submm bands, in order to optimally choose quasars for use as interferometric calibration sources. Through this monitoring effort, we have been following increasing millimeter/submillimeter band emission from 3C454.3 (J2253+161). 3C454.3 has been very active for the past 18 months, with frequent flaring activity noted in NIR, optical, UV, and gamma-ray bands, including extraordinary emission in just the past few weeks (see ATel #2988, ATel #2995, ATel #3003, ATel #3005, ATel #3022, and ATel #3034 for the most recent reported activity).

Here we report that the millimeter/submillimeter band flux density for 3C454.3 has been steadily increasing since the beginning of October 2010. On 30 September we found the 1.3mm-band flux density to be 20.6+/-1.1 Jy. Our most recent measurements on 17 November show that the 1.3mm-band flux density has doubled over a roughly seven week period, to 41.0+/-2.0 Jy. This essentially equals that seen during the incredible flare seen in 2005 (peak flux density of that flare at 1.3mm measured with the SMA was 42.7+/-2.1 Jy occurred 27 June 2005). A figure showing SMA measurements of 3C454.3 since early June 2010, as well as one starting in early 2003 to show the long term mm/submm band history, can be accessed at the link provided at the bottom of this ATel.

Past flares (e.g. 2005, 2007, 2008) have typically proceeded for many weeks, followed by a variably-long period of relatively steady flux density, often succumbing with a rapid decrease to a background state near 3 Jy. This suggests that 3C454.3 may continue to brighten, or at least stay steady, in the millimeter and submillimeter bands over the weeks to come. Given that strong activity is seen across the spectrum from mm to gamma rays, it is our opinion that continued monitoring of the source at all wavelengths is warranted as this flare progresses.

[The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics, and is funded by the Smithsonian Institution (USA) and the Academia Sinica (Taiwan).]

Submillimeter Array Observations of a 3C454.3 Millimeter-Band Flare

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