DUTCH OPEN TELESCOPE Report for NOVA ISC meeting nr. 17 February 17, 2005 R.J. Rutten, R.H. Hammerschlag, F.C.M. Bettonvil Overview -------- - Halpha morph on APOD - spectacular first Halpha movies - external interests largely fill the DOT schedule for 2005, with increasing co-scheduling of the DOT and the SST - progress in building the final Ba II 4554 tomography channel - progress in establishing a formal agreement with the IAC - "Students-to-DOT" program successful and to be continued - Christoph Keller starts July 1 as professor at SIU Project management ------------------ The DOT efforts are funded until 2008 through a guarantee of the UU Faculteit Natuur- en Sterrenkunde with commitments from UU and NOVA. Utrecht solar physics has been formally reintegrated with astronomy. For about a year it was a formally separated research program of the Faculty of Physics and Astronomy under Rutten. The SIU now again encompasses a single program Astronomy with SIU director N. Langer as integral program leader. The DOT team presently consists on the solar physics side of R.J. Rutten (UU), postdocs P. Suetterlin (UU via ASTRON) and K. Tziotziou (EC via ESMN), AIO's A.G. de Wijn (UU) and J. Leenaarts (UU), and external PhD student Peter G\"om\"ory (Marie Curie via NOVA); 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 (in particular A. Jaegers and P.W. Hoogendoorn). The negotiations with respect to an UU professorship were succesfully concluded when Christoph U. Keller, presently of the US National Solar Observatory at Tucson, accepted the position. He starts July 1, 2005. He will be active both in solar and non-solar instrumentation, observation, and analysis. A solar-oriented proposal for Marie Curie EXT funding was already submitted. The EC awarded a two-year Marie Curie EIF postdoc fellowship to Julius Koza of Tatranska Lomnica, Slovakia. He starts this summer. The DOT TAC (external members Oskar von der Luehe, director Kiepenheuer Institut in Freiburg; Goran Scharmer, director Institute for Solar Physics, Stockholm; Bernhard Fleck, SOHO mission scientist for ESA, Goddard) peer-reviewed the allocation of OPTICON time for 2005. DOT scheduling for the 2005 season is presently performed in close consultation with the SST TAC. The DOT++ plans for DOT aperture tripling remain on hold. One constraint is that the US National Solar Observatory has selected Haleakala as site for the ATST. Another was an Italian feeler to move the DOT to Dome C. The most important constraint is the Solar-B mission of which the launch is still planned for late 2006. Progress since ISC 16 --------------------- Camera control: so far the camera control software has not been able to reach the nominal and desired 12 frames per second speckle image acquisition rate. It should now work, but cannot be tested yet because the inter-camera synchronization software does not function properly. External help has now been hired to remedy this problem. Tunable Halpha Lyot filter: precise alignment completed. Problems with air bubbles arose as expected (the filter was not used for many years) and have been solved as expected by refilling with the appropriate silicon oil (specific refractive index, no degradation at the high operating temperature). The precise synchronization between the Halpha camera and the red-continuum camera, a necessity for two-channel (wide and narrow band) speckle reconstruction, is now also being addressed by the external expert. The filter control (per PC104) is ready but awaits proper synchronization. So far the Halpha profile has been sampled by manual (i.e. simple script) control between successive speckle bursts, but when the synchronization problem is solved full computer control of the Halpha profile scanning, a scientific must to disentangle Dopplershift from brightness variations, will be feasible. After the installation of the Halpha filtr in September excellent data sets were obtained using script control. The first movies are coming out of the speckle reconstruction (still slow, awaiting the DSP) and are spectacular. Some sequences were the product of a French-led multi-telescope campaign where THEMIS supplied vector field topology (see http://bass2000.bagn.obs-mip.fr/jop178/oct6/oct6.html) and are presently analysed in detail by the Fench. Our own Halpha research has started with an analysis of why its wings portray magnetic elements so brightly. Ba II 4554 Lyot filter: the detailed design including mechanical mounting for this final DOT tomography channel is complete. Most optical components for the required re-imaging, beam folding, telecentricity and aberration corrections, about 15 in total, are in house. The mechanical mounts are in fabrication at IGF. Polarimetry with the Ba II filter: TUE student Frans Snik graduates soon on the design and tests to employ the Ba II filter for polarimetry, eventually aiming at full Stokes vector analysis (both Zeeman polarization and Hanle depolarization). Initial tests were performed using liquid crystal retarders. DOT speckle processor: all hardware is installed in the transit telescope building 100 meter downslope of the DOT which formerly belonged to Denmark and now transits to IAC proprietorship on behalf of a Spanish Navy group performing astrometry (ROA). The fiber connections to the SST building have been laid. The elaborate water cooling system, piping water along all 70 Xeon processors with storage in a water tank for cooling at sunset, is installed. Software installation and verification is the next step. Formal agreement with the IAC: there is severe pressure from the IAC to finally formalize the DOT's presence on La Palma through an official agreement. The notion of a national agreeement (or one at the NWO level) has been dropped in favor of an institutional IAC-UU agreement. The main item is a charge of 8000 Euro/year, indexed to 2005 and intended for "IAC post-graduate training", in addition to the regular site costs (the common services controlled by the CCI) which we already pay. This amount is substantially less than earlier claims and seems reasonable. An IAC-formulated concept, acceptable in the view of the DOT team, now lies at the UU Faculty of Physics and Astronomy studies. It proposes automatic continuation with one year notice of ending on both sides. As preparation for this agreement, and at the explicit demand of the IAC, three DOT containers have been moved off-site to the work buildings near the Residencia, and a general site clean-up has been performed. The "Students-to-the-DOT" initiation was very successful. Four students came to La Palma, in two pairs spending two weeks each. They worked on solar physics projects using initial DOT data in order to define and outline future DOT science programs and observing strategies. DOT seminars were started, 2-4 presentations per week by the students, by the DOT team, and by visiting solar physicists (in particular from Oslo as "USO Seminars"). The students also visited other La Palma telescopes. Three of the four continued their projects at Utrecht to the extent of 7.5 and 15 ECTS. Major meetings -------------- CCI-OSC: RdlM, 27 September, Hammerschlag CCI: La Laguna, 28-29 October, Hammerschlag and Bettonvil OPTICON: Observatoire Haute Provence, 17-18 November, Bettonvil DOT campaigns ------------- "Center-to-limb variation of photospheric bright points", September 23 - October 1, combining DOT with SST, VTT, and THEMIS; CCI-ITP campaign led by Suetterlin "Filaments and their environment", October 5 - 15, DOT, THEMIS, VTT, OP telescopes at Meudon, Pic du Midi, NSO/DST, SOHO, TRACE, led by Th. Roudier "Sunspot dynamics", November 23 - December 2, DOT, VTT, SST, SOHO, TRACE led by H. Balthasar The DOT schedule for 2005 is presently being defined. It will certainly contain an International Time Program campaign led by Japanese colleagues, two (probably three) OPTICON campaigns by European teams, two Spanish-time campaigns, and two campaigns led by American colleagues (Lockheed-Martin) with NASA support for DOT operation. DOT-directed co-pointing with a USA rocket launch is also on the list. At least four campaigns will involve co-pointing the DOT and the SST, a desirable strategy because the SST offers complementary diagnostics at yet higher resolution while the two telescopes share virtually identical seeing. Milestones ---------- The first Halpha mosaic served in a beautiful "morph" as APOD display on Feb 16, 2005. It transits from the G-band photosphere through the Ca II H low chromosphere to the Halpha high chromosphere. It eminently illustrates the power of DOT tomography, in particular by adding the Halpha fibrils as outline of chromospheric ("canopy") field topology. In the meantime, the initial Halpha movies coming out of the speckle reconstruction vividly demonstrate that single exposures are beautiful but no good: the dynamics are terrific and indeed require DOT-like movie making at sustained high resolution. Plans for the coming half year ------------------------------ Halpha will undoubtedly become the major DOT diagnostic. However, the line is notoriously difficult to interpret quantitatively; appropriate radiative transfer modeling effort is starting up as well (bright-point analysis by Leenaarts and Suetterlin; profile inversion by Tziotziou and visiting student Adam Hosford; radiative transfer by Leenaarts and Rutten). Work on the Ba II 4554 channel, including the construction of an extra camera in the nearby continuum to improve the angular resolution through two-channel speckle reconstruction and further polarimetry tests using liquid crystal retarders. The Irkutsk filter builders, V.I. Skomorovskiy and G.N. Domychev will come nearly a month to Utrecht inspring on INTAS funding to check and optimise the calcite alignments and mechanical controls. Polarimetry with the Ba II 4554 filter: continue testing. DOT students: continue the program at a volume of 8-10 two-week stays. DOT VSO server: we aim to purchase and set up a large-volume DOT data server at Utrecht which will be an integral part of the Virtual Solar Observatory presently being tested in the USA. Its data capacity will be about 5 TByte, enough for the coming three-year harvest (after speckle reconstruction with the DSP on La Palma which effectively implies 100-fold compression). Transport from La Palma to UU will probably be done per carried disks, with prior backup on DVDs. The operation and maintenance will be handled by the computer group of the UU Faculty of Physics and Astronomy. A funding proposal is in preparation. The start of the DOT observing has been planned for mid-May, leaving time at Utrecht for the BaII work with the Russian filter builders and at La Palma for DSP start-up and for further site cleaning as required by the IAC. This summer will be the start of the DOT frequent observing mode with fast data product turnaround. Bettonvil aims to move to La Palma with his family; Rutten with his wife. Publications ------------ J. Leenaarts, S. Wedemeyer-Boehm, 2005, "DOT tomography of the solar atmosphere III. Observations and simulations of reversed granulation", A&A, 431, 687 F.C.M. Bettonvil, R.H. Hammerschlag, P. Suetterlin, R.J. Rutten, A.P.L. Jaegers, 2004, "DOT++: Dutch Open Telescope with 1.4-m aperture", SPIE 5489, 362 R.H. Hammerschlag, O. von der Luehe, F.C.M. Bettonvil, A.P.L. Jaegers, F. Snik, 2004 "GISOT: A giant solar telescope", SPIE 5489, 491 The next three papers in the A&A series "DOT tomography of the solar atmosphere" are being prepared. They address Halpha bright points (Leenaarts + Suetterlin), a surge in active region AR10486 just before it sent off the largest flare ever recorded (K. Tziotziou et al.), and a new view of internetwork magnetism (de Wijn et al.). Critical areas -------------- The lack of manpower, in particular technical support of sufficient quality in software and electronics, and the comparatively low funding level remain major critical constraints. For example, much delay occurs because the present software controlling the cameras and image acquisition does not function properly and the interfacing with the filter control remains incomplete. This problem is somewhat remedied by hiring temporary external help, but the lack of a knowledgeable systems engineer devoted to the DOT is a strong permanent drawback. The negotiations between the IAC and UU to reach an official agreement regarding the DOT status on La Palma may gain from mediation by the ISC Chair.