DUTCH OPEN TELESCOPE Report for NOVA ISC meeting nr. 14 September 14, 2003 R.J. Rutten and F.C.M. Bettonvil Overall ------- The major DOT advances are that: - four wavelength channels are in operation; - NWO has granted the Dot Speckle Processor (DSP); - negotiations with solar physics professor candidate #1 have started. A major objective remains to "open the DOT" by the summer of 2004: to exploit the full (not just Utrecht-only) DOT science capacity through frequent sharing in international multi-telescope campaigns through common-user time allocation including PI-led student service. The DOT science prospects are excellent in particular thanks to the DSP grant. With it, the DOT can frequently deliver multi-hour tomographic speckle imaging of Solar-B (0.2 arcsec) quality, pre-empting the imaging goals of this space mission by beating atmospheric seeing though speckle reconstruction. Adaptive optics (AO) combined with new (appropriate small-pixel) spectropolarimeters at the neighbouring Swedish 1-m Solar Telescope (SST) and the Dunn Solar Telescope (DST) at Sacramento Peak will similarly pre-empt Solar-B's Stokes-vector spectropolarimetry from 2004. Tandem observing combining co-targeted 0.2 arcsec DOT speckle tomography and 0.2 arcsec SST/DST AO spectropolarimetry will therefore generate Solar-B science years before the mission flies. Solar-B will provide such diagnostics 24 hours a day from 2006-2007, but thanks to the advent of speckle and AO "seeing beating" many of its science quests will become addressable next year already. Project management ------------------ The DOT team presently consists on the solar physics side of R.J. Rutten (UU, PI), postdocs P. Suetterlin (NWO) and K. Tziotziou (EC-ESMN), AIO's A.G. de Wijn and J. Leenaarts, and on the technical side of R.H. Hammerschlag (UU) and F.C.M. Bettonvil (NWO via ASTRON), with much support from the Faculty workshop IGF (including A. Jaegers and P.W. Hoogendoorn) and part-time support from SIU programmer E.B.J. van der Zalm. The UU Faculteit Natuur- en Sterrenkunde formally separated Utrecht solar physics from the "Astrophysics program" into the "Solar Astronomy" research program per December 15, 2002. The program remains part of the Sterrekundig Instituut Utrecht but its financing by the Faculteit is planned to be separate, including direct responsibility to the Faculty. Rutten is ad-interim program leader awaiting the new solar physics professor. However, the separation has not been financially implemented so far, and it seems not unlikely that the recent "van-Bemmel protocol" visitation of the Faculteit will lead to re-integration of the two programs. The search committee for a UU Solar Physics professor led to the selection of two high-level candidates. Negotiations with the first one have started. AIO J. Leenaarts started PhD studies on solar physics with emphasis on the interpretation of DOT-observed dynamics on September 15, 2003. The two solar SMEX mission proposals in which the DOT participates (with Rutten as Co-I) compete for selection by NASA in September. Progress since ISC 13 --------------------- At the end of the preceding report period bad weather on La Palma made it impossible to install and complete the third and fourth wavelength channels of the multi-wavelength tomography system. This happened in the first campaign of the present reporting period. The red continuum and Ca II H filters, optics, and fiber links were installed and perform very well. All four cameras were carefully aligned using their new (X,Y,rotation,shift)-adjustable mounts to obtain precise co-spatiality. A beautiful fade-over between all four wavelengths, featuring a large active region in a three-by-three image mosaic, illustrates the tomographic nature of the wavelength switching vividly (DOT website http://dot.astro.uu.nl under "Showpieces"). The computer control of these filters employs PC-104 modules and represents the start of a new Linux-based control network for the whole multi-wavelength system operation designed by D. van Tricht (funded by SOZOU). Both new filters are mounted in computer-controlled tiltable holders. For Ca II H such tilting implies shifting the passband from line center into the blue line wing. It is formed deeper the further out, and obeys LTE in its formation from 0.2 nm out making it unusually straightforward to interprete. Very promising data sets with both passband switching to cover the Ca II H wing and positional switching to cover the solar disk-center variation were obtained and are presently being speckle-reduced. For the red continuum the filter tilting implies passband shifting from Halpha line center though the Halpha wing into the continuum. Using it at line center is intended to register all photons (whatever their Dopplershift) in the emission line from off-limb prominences. An intriguing discovery is that the outer H-alpha wing displays tiny intergranular magnetic elements with similar contrast enhancement as in the molecular G band. IGF-mechanics is well underway with the mechanical mount of the large Zeiss Lyot filter for narrowband tunable Halpha observation; completion is foreseen this autumn. The mount includes thermal isolation since the filter will be kept at 40 C. It will be controlled via the new PC-104 Linux module system, including translational shift to select the most homogeneous calcite surface for the intermediate image location. ASTRON continues work on the fabrication of the optics for the Ba II 4554 channel. This Lyot filter (from Irkutsk) is very large. It will serve to produce high-resolution Dopplergrams. Its mount and control system will be similar to those of the Halpha filter, and therefore straightforward to produce. Eventually, it may also serve to produce magnetograms using liquid-crystal polarization analysis, but this application requires further experimentation. The removable wood-panel floor on the DOT platform was completed (Hoogendoorn). IGF-electronics has adapted the speckle-frame acquisition software in order to permit Halpha wavelength switching. The synchronisation of the CCD cameras (Hitachi) has been improved to 80 microsec (necessary for Halpha because it requires two-channel speckle reconstruction using the wide-band red continuum camera to provide seeing measurements at high S/N). IGF-electronics has also improved the camera frame rates from 6 to 12 fps. There is aso contact with Hitachi itself regarding the camera linearity, which is found to be sub-par and temperature-sensitive. Hitachi is performing tests and seeking corrections. NWO's award of the DOT Speckle Processor (DSP, proposal under "Documents" on the DOT website) represents an enormously important step forward. It will cure the severe processing bottleneck described in our previous reports. We are already swamped with data - presently suffering a processing backlog of over a year - from running four cameras in limited intermittent campaigns only. The DSP is designed to deliver overnight processing capability for full-day speckle runs of all six speckle cameras at full clip - up to 1.6 Terabyte per observing day. It will enable us to "open up" the DOT to the international community, in particular for frequent co-observing in multi-telscope campaigns, and so generate DOT data and DOT science on an international scale instead of a Utrecht-only scale (requests for DOT co-observing are regularly turned down at present). The DSP processor farm design is hybrid and advanced. A technical complication is that the heat generated by the many processors (order of 100, probably dual Xeon's) must be buffered to restrict open-air dissipation to sunset and sunrise only, when neither daytime nor nighttime observing is hampered. Negotiations with three vendors are well advanced and very promising. Major meetings -------------- March 26 - 28, Hammerschlag: GREGOR design evaluation, Freiburg. April 2 - 5, Rutten + Suetterlin: SST science planning workshop, Stockholm. Rutten gave the workshop summary. June 23, Rutten: NOVA2 presentation to NOVA's IAB, Groningen. August 25 - 27, Rutten: Advanced Technology Solar Telescope Conceptual Design Review, NSO/Sacramento Peak (NM). The ATST (400 cm, high-order AO, coronagraphic capability, timeline 2010) is now designed to have an "open dome": one that maintains the telescope at ambient temperature and admits wind as if it were open. The ATST cost estimate has risen to 160 M$. The initial site selection is slated for this autumn (down to one or two from six tested candidates, three in the continental US plus La Palma, Baha California, and Haleakala). DOT campaigns ------------- April 23 - May 7, Bettonvil, Hammerschlag, Suetterlin, Jaegers: installation of the red continuum and Ca II H channels, science observing, speckle interferometry tests with the SST at the request of G. Scharmer. June 5 - 19, Bettonvil, Hammerschlag, Suetterlin: science observing. July 5 - 19, Bettonvil, Hammerschlag, Suetterlin: science observing jointly with THEMIS (C. Briand) and SST (E. Wiehr). August 2 - 16, Bettonvil, Hammerschlag, Suetterlin: science observing jointly with VTT (L. Bellot). Visitors -------- April 27 - 29, La Palma: NVWS Werkgroep Zon, DOT visit and talks. May 3, La Palma: A.J. Meijler and R. Stark (NWO), DOT visit. August 8 - 11, La Palma: UU officials (Rector W.H. Gispen, CvB member W. Kardux, the full Faculty board, incoming Dean W. de Ruijter, and E.P.J. van den Heuvel (NOVA), DOT visit and talks. August 19 - September 11, Utrecht: Ir. R. Friedlein (Kiepenheuer Institut, Freiburg), technical consultations. September 9 - 10, Utrecht: Dr. S. Rengaswamy (Udaipur Solar Observatory): technical consultations regarding the Indian MAST (new national solar telescope) project. Milestones ---------- DSP awarded by NWO, see above. EC recommendation to include the DOT in the "Access" program award to OPTICON. The precise level is being negotiated. Rutten: talks on DOT solar physics at Stockholm, Boulder (NCAR-HAO and CASA), Montana State University (Bozeman). Relations with collaborators ---------------------------- The DOT-like (but larger) foldaway clamshell canopy for the German GREGOR telescope (Tenerife, 150 cm, 2005) is being fabricated at TU Delft under the supervision of the DOT engineers and proceeds well. Rutten coordinated international support for multi-partner Swedish graduate-student supervision. The DOT team participates in an effort to obtain European partnership in the US ATST project through EC-FP6 funding. Critical areas -------------- The relatively low budget, smallness of the DOT team, and soft-money funding of two of the four core members remain major critical constraints. Plans for the coming half year ----------------------------- Scheduled science observing: October 30 - November 7, with THEMIS. Completion of the multi-wavelength tomography system: Halpha this autumn and winter, Ba II 4554 in the late spring. DSP procurement and installation: winter and spring. Installation of an international DOT Time Allocation Committee and announcement of DOT availability for multi-telescope campaigns, in preparation for the frequent observing enabled by the DSP. Definition of and preparation for the DOT Education Program, intended to bring up to 20 students during two weeks in pairs to La Palma to help observing, receive a solar physics course (exploiting the excellent Swedish library), and work on a pertinent project (up to 7.5 ects altogether). It will be a yearly program and help to implement full-time DOT operation during the summer months. Our plan is to recruit students from Utrecht locally, via NOVA from the other Dutch astronomy institutes, and via the ESMN from other EC and the EC-Associated countries.