Kneer, Franz

[["dc.bibliographiccitation.firstpage","880"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","Astronomische Nachrichten"],["dc.bibliographiccitation.lastpage","893"],["dc.bibliographiccitation.volume","333"],["dc.contributor.author","Puschmann, K. G."],["dc.contributor.author","Denker, C."],["dc.contributor.author","Kneer, F."],["dc.contributor.author","Al Erdogan, N."],["dc.contributor.author","Balthasar, H."],["dc.contributor.author","Bauer, S. M."],["dc.contributor.author","Beck, C."],["dc.contributor.author","Gonzalez, N. Bello"],["dc.contributor.author","Collados, M."],["dc.contributor.author","Hahn, T."],["dc.contributor.author","Hirzberger, J."],["dc.contributor.author","Hofmann, Albrecht W."],["dc.contributor.author","Louis, R. E."],["dc.contributor.author","Nicklas, H."],["dc.contributor.author","Okunev, O."],["dc.contributor.author","Martinez Pillet, V."],["dc.contributor.author","Popow, E."],["dc.contributor.author","Seelemann, T."],["dc.contributor.author","Volkmer, R."],["dc.contributor.author","Wittmann, A. D."],["dc.contributor.author","Woche, M."],["dc.date.accessioned","2018-11-07T09:04:01Z"],["dc.date.available","2018-11-07T09:04:01Z"],["dc.date.issued","2012"],["dc.description.abstract","The GREGOR Fabry-Perot Interferometer (GFPI) is one of three first-light instruments of the German 1.5-meter GREGOR solar telescope at the Observatorio del Teide, Tenerife, Spain. The GFPI uses two tunable etalons in collimated mounting. Thanks to its large-format, high-cadence CCD detectors with sophisticated computer hard- and software it is capable of scanning spectral lines with a cadence that is sufficient to capture the dynamic evolution of the solar atmosphere. The field-of-view (FOV) of 50 ' x38 ' is well suited for quiet Sun and sunspot observations. However, in the vector spectropolarimetric mode the FOV reduces to 25 ' x38 '. The spectral coverage in the spectroscopic mode extends from 530-860 nm with a theoretical spectral resolution of R approximate to 250 000, whereas in the vector spectropolarimetric mode the wavelength range is at present limited to 580-660 nm. The combination of fast narrow-band imaging and post-factum image restoration has the potential for discovery science concerning the dynamic Sun and its magnetic field at spatial scales down to similar to 50 km on the solar surface. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim"],["dc.identifier.doi","10.1002/asna.201211734"],["dc.identifier.isi","000310799500015"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/25018"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-v C H Verlag Gmbh"],["dc.relation.issn","0004-6337"],["dc.title","The GREGOR Fabry-Perot Interferometer"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.subtype","letter_note"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","364"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Astronomische Nachrichten"],["dc.bibliographiccitation.lastpage","365"],["dc.bibliographiccitation.volume","324"],["dc.contributor.author","Al, N."],["dc.contributor.author","Hirzberger, J."],["dc.contributor.author","Kneer, F."],["dc.date.accessioned","2018-11-07T10:41:59Z"],["dc.date.available","2018-11-07T10:41:59Z"],["dc.date.issued","2003"],["dc.description.abstract","In May 2002, the solar chromosphere was observed with a two-dimensional spectrometer which is mounted in the German Vacuum Tower Telescope (VTT) at the Observatorio del Teide/Tenerife. The aim of this observation was to investigate the fine structure of the solar chromosphere seen in Halpha..We took narrow-band filtergrams (Deltalambda approximate to 72 mAngstrom) by scanning through this line. broad-band images taken strictly simultaneously with the narrow-band filtergrams were restored by speckle methods. The instantaneous optical transfer function from this restoration procedure was used for the reconstruction of the narrow-band images. Some results of this high spatial resolution observation are presented below."],["dc.identifier.doi","10.1002/asna.200310129"],["dc.identifier.isi","000183506400036"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/46676"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-v C H Verlag Gmbh"],["dc.publisher.place","Weinheim"],["dc.relation.conference","Workshop on From the Gregory-Coude Telescope to GREGOR - A Development from Past to Future"],["dc.relation.eventlocation","GOTTINGEN UNIV, III PHYS INST, GOTTINGEN, GERMANY"],["dc.relation.issn","0004-6337"],["dc.title","Two-dimensional speckle spectroscopy of H alpha features"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","375"],["dc.bibliographiccitation.issue","5-6"],["dc.bibliographiccitation.journal","Astronomische Nachrichten"],["dc.bibliographiccitation.lastpage","378"],["dc.bibliographiccitation.volume","322"],["dc.contributor.author","Kneer, F."],["dc.contributor.author","Hirzberger, J."],["dc.date.accessioned","2018-11-07T09:29:27Z"],["dc.date.available","2018-11-07T09:29:27Z"],["dc.date.issued","2001"],["dc.description.abstract","Fabry-Perot interferometers (FPIs) are powerful instruments for spectro-polarimetry of the Sun with high spatial resolution. They allow easy image reconstruction of two-dimensional fields of view. Some examples of high quality results obtained with the \"Gottingen\" FPI spectrometer, mounted in the Vacuum Tower Telescope at the Observatorio del Teide/Tenerife, are presented in a poster to this workshop. We thus concentrate on the design of a new instrument for the 1.5 m GREGOR solar telescope. We discuss the pros and cons of telecentric and collimated mounting and describe the expected performance, especially the spectral resolution, of our design."],["dc.identifier.isi","000173097200019"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/31032"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-v C H Verlag Gmbh"],["dc.publisher.place","Weinheim"],["dc.relation.conference","JENAM 2001 Meeting held in Conjuction with the 10th Meeting of the European-Astronomical-Society/75th Annual Assembly of the Astronomische-Gesellschaft"],["dc.relation.eventlocation","LUDWIG MAXIMILIAN UNIV, MUNICH, GERMANY"],["dc.relation.issn","0004-6337"],["dc.title","A Fabry-Perot spectrometer for high-resolution observation of the Sun"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","551"],["dc.bibliographiccitation.issue","5-6"],["dc.bibliographiccitation.journal","NUOVO CIMENTO DELLA SOCIETA ITALIANA DI FISICA C-GEOPHYSICS AND SPACE PHYSICS"],["dc.bibliographiccitation.lastpage","555"],["dc.bibliographiccitation.volume","25"],["dc.contributor.author","Wunnenberg, M."],["dc.contributor.author","Hirzberger, J."],["dc.contributor.author","Kneer, F."],["dc.date.accessioned","2018-11-07T10:08:02Z"],["dc.date.available","2018-11-07T10:08:02Z"],["dc.date.issued","2002"],["dc.description.abstract","The data for this contribution were taken in August 2000 with the \"Gottingen\" two-dimensional spectrometer in the VTT on Tenerife. Our spectrometer is based on two scanning Fabry-Perot Interferometers (FPIs). The non-magnetic Fe I 5434 Angstrom line was observed in the quiet Sun at disk center. Time sequences of 41 min duration and with 25 s cadence were taken. Strictly simultaneously with the narrow-band FPI images (32 mAngstrom FWHM), broad-band images were recorded. The latter were reconstructed with speckle methods. With the known \"true\" broad-band object we are able to restore the narrow-band images as well. Our aim is to find propagating acoustic waves at short periods and small scales. The results obtained so far are presented and the prospects are discussed."],["dc.identifier.isi","000181412800006"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/39399"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Editrice Compositori Bologna"],["dc.publisher.place","Siena"],["dc.relation.eventlocation","ROME, ITALY"],["dc.relation.issn","1124-1896"],["dc.title","Search for short-period acoustic waves with high-resolution 2D spectra"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Astronomische Nachrichten"],["dc.bibliographiccitation.volume","324"],["dc.contributor.author","Kneer, F."],["dc.contributor.author","Al, N."],["dc.contributor.author","Hirzberger, J."],["dc.contributor.author","Nicklas, H."],["dc.contributor.author","Puschmann, K. G."],["dc.date.accessioned","2018-11-07T10:41:57Z"],["dc.date.available","2018-11-07T10:41:57Z"],["dc.date.issued","2003"],["dc.format.extent","302"],["dc.identifier.doi","10.1002/asna.200310102"],["dc.identifier.isi","000183506400009"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/46663"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-v C H Verlag Gmbh"],["dc.publisher.place","Weinheim"],["dc.relation.conference","Workshop on From the Gregory-Coude Telescope to GREGOR - A Development from Past to Future"],["dc.relation.eventlocation","GOTTINGEN UNIV, III PHYS INST, GOTTINGEN, GERMANY"],["dc.relation.issn","0004-6337"],["dc.title","A Fabry-Perot spectrometer for high-resolution observation of the Sun"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","L51"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","L54"],["dc.bibliographiccitation.volume","395"],["dc.contributor.author","Wunnenberg, M."],["dc.contributor.author","Kneer, F."],["dc.contributor.author","Hirzberger, J."],["dc.date.accessioned","2018-11-07T09:43:26Z"],["dc.date.available","2018-11-07T09:43:26Z"],["dc.date.issued","2002"],["dc.description.abstract","Short-period acoustic waves are thought to supply the energy for the radiative losses of the non-magnetic chromosphere of the Sun and, in general, of late-type stars. Here, we present evidence for the existence of waves in the solar atmosphere with periods in the range of 50s < P < 100 s. Two-dimensional time sequences with a cadence of 25 s were obtained from quiet Sun disk center in Fe I 5434 Angstrom. The observations were performed with the \"Gottingen\" Fabry-Perot spectrometer in the Vacuum Tower Telescope at the Observatorio del Teide/Tenerife. They are subjected to speckle reconstruction and to a wavelet analysis. The atmospheric ranges forming the velocity signals are narrowed by linear combinations of Doppler maps from wavelengths near line center. The power in the short-period range is concentrated above intergranular spaces. We estimate an acoustic flux into the chromosphere of approximately 3 x 10(6) erg cm(-2) s(-1), as needed for the chromospheric radiative losses."],["dc.identifier.doi","10.1051/0004-6361:20021531"],["dc.identifier.isi","000179291200002"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/34184"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","E D P Sciences"],["dc.relation.issn","0004-6361"],["dc.title","Evidence for short-period acoustic waves in the solar atmosphere"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]