Received: 17 August 2000 JOP097 Coordinated observing campaign with SOHO, TRACE, and GBOs (JOP097) Title: OSCILLATIONS IN SUNSPOTS AND ACTIVE REGIONS Instruments: TRACE (EOF GSFC) SOHO MDI (EOF GSFC) SOHO CDS (EOF GSFC) VTT (Tenerife) GCT (Tenerife) DOT (La Palma) Scientists and institutes: K. Muglach (campaign coordinator) AIP, Potsdam H. Balthasar AIP, Potsdam A. Hofmann AIP, Potsdam V. Landgraf AIP, Potsdam M. Collados Vera IAC, Tenerife R.J. Rutten University Utrecht P. S"utterlin University Utrecht E. O'Shea ESA/ESTEC B. Fleck ESA/GSFC TRACE team MDI team Update of campaign: 17.8.2000 Scientific rationale: Recently, oscillations of the magnetic field B in sunspots and pores came into discussion. Two dimensional ground-based observations by Horn et al. (1997) and Balthasar (1999) show their existence and time-sequences of sunspots and their surroundings taken by MDI show a clear but highly localized oscillatory signal in the magnetic flux in the 3 -- 6 mHz frequency range. The observed phase relations between the magnetic and velocity oscillations indicate that the magnetogram oscillations are due to magnetoacoustic waves (Norton et al., 1999, R"uedi et al., 1998). As measurements with high magnetic sensitivity are required, we will use the new IAC Stokes polarimeter in the IR, which can obtain all four Stokes parameters with full spectral resolution (Sanchez et al. 1997). At 1.56 mu an Fe I line with a high Lande-factor exists (g=3), which is very sensitive to the magnetic field and thus is well suited for measurements of magnetic fields in moderate sized sunspots as well as in active regions (Muglach & Solanki, 1992, Solanki et al. 1992). First indications of oscillations of the magnetic field B in a plage area have also been detected with this particular IR line (Muglach et al. 1995). We would also like to follow the photospheric oscillations up into the higher solar atmosphere. CDS and TRACE can probe the chromosphere and corona and should provide a better understanding of the nature of the dynamic evolution of the solar plasma in response to photospheric driving mechanisms and the structure given by the magnetic field. In particular, we are interested in investigating the high frequency oscillations that are known to be present in transition region and coronal lines (Ireland et al. 1999), and to investigate whether the supposed waves causing these oscillations are generated in situe in the transition region corona, or if they travel up from the lower atmosphere regions. In order to do this we plan to use CDS lines from the low transition region up to the corona. First results of last years run can be found at: - Balthasar, H., Collados Vera, M., Muglach, K.: 2000, ``Oscillations in a Solar Pore'', Astron. Nachr., 321, p. 121 - http://hst33127.phys.uu.nl/~pit/DOT/ - http://www.astro.su.se/~rouppe/umbralflash/flash.html and http://www.astro.su.se/~rouppe/poster/poster.html Last year, sunspots were our primary targets, so this year we will concentrate on the surroundings of the spots (pores, plage) with the active region on the solar disk near the center. Details of instruments: VTT: We wll get high cadence observations of slit-spectra with the IR polarimeter of the surroundgs of sunspots at the Vacuum Tower Telescope (VTT) in Tenerife (Muglach, Balthasar, Collados). We use Fe I 15648 A and Fe I 15652 A. GCT: The Liquid Crystal based Stokes Polarimeter (LCSP) will be in operation at the Gregory Coude Telescope (GCT) observing the full Stokes vector and time series of Stokes I and V of the same region in the visible with Fe I 6302 A (Hofmann, Landgraf). DOT: The Dutch Open Telescope (DOT) in La Palma will take high-resolution sequences of images in the G-band (Rutten, S"utterlin). TRACE: a) 1550,1600,1700 in 15s cadence, 256 x 640 pixel FOV, name of program: TDT.trnotsofast to be run for 3h every morning (+1h for emptying the memory) modification: NO wl images interleaved!! UV images are sufficient for coalignment if sunspots or pores are present in the FOV b) 1600,171,wl in 45 s cadence, 768 x 768 / 512 x 512 FOV, name of program: RAS.dynamics_4 to be run for the rest of the time MDI: For a target inside the HR FOV: hr_t2_ve_fe_me (Doppler grams, magnetograms and Igrams in 1 min cadence. For a target outside the HR FOV: p30vr_fd_m1 CDS: (a) Fe XVI 335, Mg IX 368, O III 599, O V 629, He I 584, Mg X 624 in 20 s cadence, 4 x 240 arcsec slit to be used. To be run as often as possible, in 3 h runs, starting everyday at 07:00 UT, to match TRACE oscillation programs, and ending at 17:00 UT. (b) Rasters of Fe XVI 335, Mg IX 368, O III 599, O V 629, He I 584, Mg X 624, O II 616, Si IX 345, Si IX 349, Mg VI 349, Ne VI 562, Fe XIII 320, Fe XIII 348, Ca X 557 with 30 second exposure time. To be run and completed every morning before 07:00 UT and thereafter before and after every CDS oscillation sequence as described in (a) above. For comparison to the TRACE fast oscillation program TDT.trnotsofast, which has a 256 x 640 pixel (128 x 320 arcsec^2) FOV, the CDS raster size during and just before and after the time of these TRACE observations (07:00-17:00 UT) is to be 120 x 240 arcsec^2. At all other time the raster size will be the 'standard' size of 240 x 240 arcsec^2. As there is no complete overlap of all ground-based telescopes, we would like to ask for support of CDS, MDI and TRACE for: 19.09.-29.09.2000, 07:00 - 17:00 UT ----------------------------------------------- Target selection will be done at TF and pointing coordinates given one day before (and on Friday for Sat,Sun and Mon). Coordinator will be K. Muglach (at Tenerife), POC at the EOF will be E. O'Shea. References: Balthasar, H.: 1999, Solar Phys., in press Horn, T., Staude, J., Landgraf, V.: 1997, Solar Phys. 172, p.69 Ireland. J., Walsh, R.W., Harrison, R.A., Priest, E.R., 1999, A&A, 347, 355 Muglach, K., Solanki, S.K.: 1992, A&A 263, p.301 Muglach, K. Solanki, S.K., Livingston, W.C.: 1995, in Infrared Tools for Solar Astrophysics: What's Next? Kuhn, J.R., Penn, M.J. (eds.), World Scientific, p.387 Norton, A.A., Ulrich, R.K., Bush, R.I., Tarbell, T.D.: 1999, in 3rd Advances in Solar Physics Euroconference. Magnetic Fields and Oscillations, ASP Conf. Ser., B. Schmieder, A. Hofmann, J. Staude (eds.), submitted. R"uedi, I., Solanki, S.K., Stenflo, J.O., Tarbell, T., Scherrer, P.H.: 1998, A&A 335, L97 Sanchez Almeida, J., Collados, M., Martinez Pillet, et al.: 1997, in 1st Advances in Solar Physics Euroconference, Advances in Physics of Sunspots, ASP Conf. Ser. Vol. 118., B. Schmieder, J.C. del Toro Iniesta, M. Vazquez (eds.), p. 366. Solanki, S.K., R"uedi, I., Livingston, W.C.: 1992, A&A 263, 312 ------------------------------------------------------------------------