Skip to main content
Log in

Joint Measurements of Flare Flux Densities at 210 – 212 GHz by Two Different Radio Telescopes

  • Published:
Solar Physics Aims and scope Submit manuscript


Multiple-beam observations of solar flares at submillimeter wavelengths need detection with at least four beams to derive the flux density \(\mbox{$F$} \) of the emitting source, its size, and centroid position. When this condition is not fulfilled, the assumptions on the location and/or size of the emitting source have to be made in order to compute \(\mbox{$F$}\). Otherwise, only a flux density range \(\mbox{$\Delta F$}\) can be estimated. We report on simultaneous flare observations at 212 and 210 GHz obtained by the Solar Submillimeter Telescope (SST) and the Bernese Multibeam Radiometer for Kosma (BEMRAK), respectively, during two solar events on 28 October 2003. For both events, BEMRAK utilized four beam information to calculate the source flux density F 210, its size and position. On the other hand, the SST observed the events with only one beam, at low solar elevation angles and during high atmospheric attenuation. Therefore, because of these poor observing conditions at 212 GHz, only a flux density range ΔF 212 could be estimated. The results show that ΔF 212 is within a factor of 2.5 of the flux density F 210. This factor can be significantly reduced (e.g. 1.4 for one of the studied events) by an appropriate choice of the 212 GHz source position using flare observations at other wavelengths. By adopting the position and size of the 210 GHz source measured by BEMRAK, the flux density at 212 GHz, F 212b, is comparable to F 210 within the uncertainties, as expected. Therefore our findings indicate that even during poor observing conditions, the SST can provide an acceptable estimate of the flux density at 212 GHz. This is a remarkable fact since the SST and BEMRAK use quite different procedures for calibration and flux density determination. We also show that the necessary assumptions made on the size of the emitting source at 212 GHz in order to estimate its flux density are not critical, and therefore do not affect the conclusions of previous studies at this frequency.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5

Similar content being viewed by others


  1. For the period of observation studied here, the SST was still undergoing surface repairs and adjustments after damage suffered before 1999. After final adjustments of the antenna surface, the aperture efficiencies were of 35 % and 20 % at 212 GHz and 405 GHz, respectively (Kaufmann et al. 2008).


  • Costa, J.E.R., Silva, A.V.R., Lüdi, A., Magun, A.: 2002, Beam profile determination by tomography of solar scans. Astron. Astrophys. 387, 1153 – 1160.

    Article  ADS  Google Scholar 

  • De la Luz, V., Lara, A., Raulin, J.P.: 2011, Synthetic spectra of radio, millimeter, sub-millimeter, and infrared regimes with non-local thermodynamic equilibrium approximation. Astrophys. J. 737, 1.

    Article  ADS  Google Scholar 

  • Fleishman, G.D., Kontar, E.P.: 2010, Sub-THz radiation mechanisms in solar flares. Astrophys. J. Lett. 709, L127 – L132.

    Article  ADS  Google Scholar 

  • Georges, C.B., Schaal, R., Costa, J., Kaufmann, P., Magun, A.: 1989, 50 GHz multi-beam receiver for radio astronomy. In: 2nd SBMO International Microwave and Optoelectronics Conference Proceedings, 447 – 449.

    Google Scholar 

  • Giménez de Castro, C.G., Raulin, J.P., Makhmutov, V.S., Kaufmann, P., Costa, J.E.R.: 1999, Instantaneous positions of microwave solar bursts: Properties and validity of the multiple beam observations. Astron. Astrophys. Suppl. 140, 373 – 382.

    Article  ADS  Google Scholar 

  • Giménez de Castro, C.G., Trottet, G., Silva-Valio, A., Krucker, S., Costa, J.E.R., Kaufmann, P., Correia, E., Levato, H.: 2009, Submillimeter and X-ray observations of an X class flare. Astron. Astrophys. 507, 433 – 439.

    Article  ADS  Google Scholar 

  • Kaufmann, P., Raulin, J.P.: 2006, Can microbunch instability on solar flare accelerated electron beams account for bright broadband coherent synchrotron microwaves? Phys. Plasmas 13, 070701.

    Article  ADS  Google Scholar 

  • Kaufmann, P., Costa, J.E.R., Giménez de Castro, C.G., Hadano, Y.R., Kingsley, J.S., Kingsley, K.K., et al.: 2001, The submillimeter-wave solar telescope. In: 2001 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference Proceedings, 439 – 442.

    Chapter  Google Scholar 

  • Kaufmann, P., Raulin, J.P., de Castro, C.G.G., Levato, H., Gary, D.E., Costa, J.E.R., Marun, A., Pereyra, P., Silva, A.V.R., Correia, E.: 2004, A new solar burst spectral component emitting only in the terahertz range. Astrophys. J. Lett. 603, L121 – L124.

    Article  ADS  Google Scholar 

  • Kaufmann, P., Levato, H., Cassiano, M.M., Correia, E., Costa, J.E.R., Giménez de Castro, C.G., et al.: 2008, New telescopes for ground-based solar observations at submillimeter and mid-infrared. In: Stepp, L.M., Gilmozzi, R. (eds.) Ground-based and Airbone Telescopes II, Proc. SPIE 7012, 70120L.

    Chapter  Google Scholar 

  • Kaufmann, P., Trottet, G., Giménez de Castro, C.G., Raulin, J.P., Krucker, S., Shih, A.Y., Levato, H.: 2009, Sub-terahertz, microwaves and high energy emissions during the 6 December 2006 flare, at 18:40 UT. Solar Phys. 255, 131 – 142.

    Article  ADS  Google Scholar 

  • Krucker, S., Giménez de Castro, C.G., Hudson, H.S., Trottet, G., Bastian, T.S., Hales, A.S., et al.: 2013, Solar flares at submillimeter wavelengths. Astron. Astrophys. Rev. 21, 58.

    Article  ADS  Google Scholar 

  • Linsky, J.L., Ayres, T.: 1973, Stellar model chromospheres. I. On the temperature minima of F, G, and K stars. Astrophys. J. 180, 473 – 481.

    Article  ADS  Google Scholar 

  • Loukitcheva, M., Solanki, S.K., Carlsson, M., Stein, R.F.: 2004, Millimeter observations and chromospheric dynamics. Astron. Astrophys. 419, 747 – 756.

    Article  ADS  Google Scholar 

  • Lüthi, T., Lüdi, A., Magun, A.: 2004, Determination of the location and effective angular size of solar flares with a 210 GHz multibeam radiometer. Astron. Astrophys. 420, 361 – 370.

    Article  ADS  Google Scholar 

  • Lüthi, T., Magun, A., Miller, M.: 2004, First observation of a solar X-class flare in the submillimeter range with KOSMA. Astron. Astrophys. 415, 1123 – 1132.

    Article  ADS  Google Scholar 

  • Melo, A.M., Kaufmann, P., Giménez de Castro, C.G., Raulin, J.P., Levato, H., Marun, A., Giuliani, J.L., Pereyra, P.: 2005, Submillimeter-wave atmospheric transmission at El Leoncito, Argentina Andes. IEEE Trans. Antennas Propag. 53, 1528 – 1534.

    Article  ADS  Google Scholar 

  • Penzias, A.A., Burrus, C.A.: 1973, Millimeter-wavelength radio-astronomy techniques. Annu. Rev. Astron. Astrophys. 11, 51 – 72.

    Article  ADS  Google Scholar 

  • Raulin, J.P., Makhmutov, V.S., Kaufmann, P., Pacini, A.A., Lüthi, T., Hudson, H.S., Gary, D.E.: 2004, Analysis of the impulsive phase of a solar flare at submillimeter wavelengths. Solar Phys. 223, 181 – 199.

    Article  ADS  Google Scholar 

  • Silva, A.V.R., Laganá, T.F., Gimenez Castro, C.G., Kaufmann, P., Costa, J.E.R., Levato, H., Rovira, M.: 2005, Diffuse component spectra of solar active regions at submillimeter wavelengths. Solar Phys. 227, 265 – 281.

    Article  ADS  Google Scholar 

  • Silva, A.V.R., Share, G.H., Murphy, R.J., Costa, J.E.R., de Castro, C.G.G., Raulin, J.P., Kaufmann, P.: 2007, Evidence that synchrotron emission from nonthermal electrons produces the increasing submillimeter spectral component in solar flares. Solar Phys. 245, 311 – 326.

    Article  ADS  Google Scholar 

  • Trottet, G., Raulin, J.P., Kaufmann, P., Siarkowski, M., Klein, K.L., Gary, D.E.: 2002, First detection of the impulsive and extended phases of a solar radio burst above 200 GHz. Astron. Astrophys. 381, 694 – 702.

    Article  ADS  Google Scholar 

  • Trottet, G., Krucker, S., Lüthi, T., Magun, A.: 2008, Radio submillimeter and γ-ray observations of the 2003 October 28 solar flare. Astrophys. J. 678, 509 – 514.

    Article  ADS  Google Scholar 

  • Trottet, G., Raulin, J.P., Giménez de Castro, G., Lüthi, T., Caspi, A., Mandrini, C.H., Luoni, M.L., Kaufmann, P.: 2011, Origin of the submillimeter radio emission during the time-extended phase of a solar flare. Solar Phys. 273, 339 – 361.

    Article  ADS  Google Scholar 

  • Ulich, B.L.: 1980, Improved correction for millimeter-wavelength atmospheric attenuation. Astrophys. Lett. 21, 21 – 28.

    ADS  Google Scholar 

Download references


This work benefited from the data of the Radio Solar Telescope Network of the US Air Force Laboratory (RSTN) provided through NGDC. JPR thanks CNPq funding agency (Proc. 305655/2010-8 and 490444/2010-5). GT acknowledges CNPq and CNRS funding agencies (Proc. 490444/2010-5). CGGC thanks FAPESP (Proc. 2009/18386-7) and CNPq (Proc. 304204/2010-2).

Author information

Authors and Affiliations


Corresponding author

Correspondence to J.-P. Raulin.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Raulin, JP., Trottet, G., Giménez de Castro, G. et al. Joint Measurements of Flare Flux Densities at 210 – 212 GHz by Two Different Radio Telescopes. Sol Phys 289, 1227–1237 (2014).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: