January 2001 Number 28 Page 1 Number 28 January 2001 This 140 nm ultraviolet image of Jupiter was taken with the Hubble Space Telescope Imaging Spectrograph (STIS) on 26 November 1998 (Credit: NASA; ESA & John T. Clarke, Univ. of Michigan) when Jupiter was at a distance of 700 million km from Earth. In addition to the main auroral oval, centred on the magnetic north pole, and a pattern of more diffuse emission inside the polar cap, unique features are the ‘magnetic footprints’ of three of Jupiter’s satellites, Io, Ganymede and Europa. Space Telescope ST-ECF Newsletter ST-ECF European Coordinating Facility Page 2 ST–ECF Newsletter European news As the ESA contribution to HST moves away Group and, in September, by the Space Science Advisory from hardware provision, support for another Committee that NGST be selected as the next ‘Flexi-mission’ project has been agreed for the ST-ECF. in ESA’s future plan for implementation between 2008 and Following the successful provision of a 2013. This selection was endorsed by the Science Programme software package for extraction of NICMOS Committee at its meeting in October. grism spectra (NICMOSLook, see ST-ECF Newsletter 24, p. 7, This approval has allowed ESA to follow up the industry 1997), support for the spectroscopic modes of the ACS will studies it funded during 1999 with new investigations also be provided. ACS has both grisms and prisms: the Wide focussed on the specific European contributions to the Field Camera, with a coverage of 3.4' × 3.4', is fitted with a mission. In November, a study of the 1–5µm near-IR multi- grism offering 40Å/pixel resolution (5500–11000Å) over the object spectrograph to be provided by ESA was awarded to a full WFC field; the High resolution Camera (26'' × 29'') consortium headed by Astrium (Munich) and Laboratoire provides 30Å/pix grism spectra and prism spectra with a d’Astronomie Spatiale (Marseille). This study is to concentrate maximum resolution of 2.6Å/pixel at 1600Å; the Solar Blind on the spectrograph concept recommended by the ad hoc Channel (31'' × 35'') has two prisms with 1.4 and 1.7Å/pixel Science Working Group (ASWG) on the basis of the science maximum resolution, with one prism excluding the programme described in the Design Reference Mission. The geocoronal Lyman-α line. The ST-ECF/ACS project is larger concept assumes a microelectronic mechanical system in scope than the NICMOS one covering all aspects of the ACS (MEMS) shutter or mirror array as its slit selector mechanism. grism and prism modes for the lifetime of the instrument, With the possibility that MEMS technology may not mature in including ground and in-flight calibration, user support and time for NGST, ESA is also in the process of soliciting a study documentation, provision of calibration files, and of course of alternatives to MEMS for generating reconfigurable front pipeline software to extract the spectra. The first output of this end slit masks. This second industrial study is scheduled to project is an imaging and spectrum simulator, called SLIM, start in March. which is described in this Newsletter. Ground calibration of The mid-infrared capability of NGST will be provided as a the spectrometric modes of ACS is just beginning and the data 50/50 collaboration between NASA and the ESA member will be analysed to determine how important is the fringing of states, with some contribution from the Canadian Space the detectors to the accurate extraction of spectra. Following Agency (CSA). A mid-infrared partnership planning group analysis of these data, the extraction software will be imple- met during 2000 and recommended that an international mented (in Python) to be run in pipeline mode but also steering committee be formed to coordinate the instrument tunable for more interactive use. design. Membership of the Mid-Infrared Steering Committee The Cycle 10 Call for Proposals in September 2000 showed (MISC) is currently being competitively solicited by the slightly lower European input, with 19.9% by number of agencies (see the ESA URL given above). The partnership proposals and 17.7% by number of GO orbits, compared with concept envisages the European team, funded from national higher figures in previous cycles. Overall, however, the contributions, developing the instrument optical and me- number of submitted proposals was almost identical to chanical structure with the US team developing the detectors Cycle 9. The allocation was announced in December and the and associated electronics and the cryocooling system. success rate for European GO orbits was also slightly lower The ASWG, which started in September 1997 and held its than previous cycles at about 16%, but still above the 15% ESA last meeting in mid-summer 2000, is being replaced by an contribution level. There were two proposals in the 50–99 Interim Science Working Group (ISWG) —see orbit category and a large snapshot proposal to build an http://ngst.gsfc.nasa.gov/project/Groups/SciWG/ archive of images of sites of core-collapse supernovæ in — whose task will be to continue providing scientific guid- nearby galaxies. However in contrast to Cycle 9, of the 14% of ance to the project until the US instrument AO is released in Large (> 100 orbit) proposals with a European PI, none were 2002. The membership was selected last September from over granted time. These are trends which could cause some 100 applicants. The group is chaired by Marcia Rieke from the concern but may perhaps be attributable to the absence of the University of Arizona and includes Mark McCaughrean (AIP) Advanced Camera for Surveys (ACS) and the cryo-cooled and Ewine van Dishoeck (Leiden) as European members. NICMOS, which were expected for Cycle 10 but are now As the technological requirements for NGST are clarified scheduled for installation during Servicing Mission 3B, and as the costing estimates become more firmly based, the expected for November 2001. NGST project has recently undertaken a detailed reassessment The pace of cross-telescope collaboration has been of the spacecraft design parameters in preparation for the accelerated by the Great Observatories Origins Deep Survey issue of the ‘Requests for Proposals’ for the NGST prime (GOODS) proposal which was accepted as a SIRTF Legacy contract in the spring of 2001. This exercise involved examin- programme. HST is involved in this program inasmuch as the ing the size and temperature of the telescope, some design HDF’s will be observed by other instruments. See choices for the instruments and the division of responsibilities http://www.stsci.edu/science/goods/ among the three agencies and the prime contractors. The main for more detail. There is substantial European involvement in result of this process has been the relaxation of the require- GOODS in the form of ground-based observations with ments on the diameter, the areal density and the temperature Gemini and ESO telescopes and which are integral to this of the primary mirror. A reduction in aperture from 8m to study of the high redshift universe. somewhere between 6 and 7m allows a stiffer mirror which Since its opening in April last year the Hubble European can be more satisfactorily tested on the ground under gravity. Information Centre has produced a steady stream of press Allowing the mirror to operate at a slightly higher tempera- releases of HST science: see the note at the end of this News- ture than would be achieved by pure passive cooling permits letter. active thermal control using heaters. Together, these options Jeremy Walsh render unnecessary the planned flight validation experiment Nexus (a 2–3 m test telescope proposed to operate at L2) which has consequently been cancelled. Several events during 2000 have advanced ESA’s The latest NASA mission update document can be significant rôle in the NGST project. In July, the obtained at: ESA NGST Study Science Team (SST) submitted a http://www.ngst.nasa.gov/cgi-bin/doc?Id=793 proposal to ESA for European participation in NGST — this Study Report is available at: Peter Jakobsen (ESTEC) & Robert Fosbury http://astro.estec.esa.nl/NGST It was strongly recommended by the Astronomy Working January 2001 Number 28 Page 3 SLIM — grism simulator for the ACS Norbert Pirzkal & Anna Pasquali LIM is a program developed at the ST-ECF to simulate ❏ Photometric zero points are computed on-the-fly using the Sdirect and slitless spectroscopic images. It was created to input list of filters and throughputs and a spectrum of Vega. generate both geometrically and photometrically realistic data ❏ Arbitrary, nth order polynomial descriptions of the disper- appropriate to the slitless spectroscopic modes of the Ad- sion relations can be used, allowing both near-linear (grism) vanced Camera for Surveys (ACS). It is based on our current and highly non-linear (prism) simulations to be generated. knowledge of the instrument parameters, the simulated data Field dependence can be included. being needed to test future slitless spectroscopy extraction ❏ Does not require any a priori sampling of the input spec- software. ACS is scheduled for launch during SM3B late in trum or throughput files. 2001. Figure 1 (a - left) direct WFC image (b) grism WFC image. Color composite direct image (F435W, F606W, F814W) and corresponding grism (G800L) image of a simulated ACS/WFC image of an HDF-N like field. Integration times are 1000s per filter. PA = 90° PA = 45° ❏ Produces Wide Field Camera (WFC) simulations that agree 15,000 15,000 V = 20 V = 20 photometrically within 1% with the ACS exposure time 10,000 10,000 calculator. 5000 5000 Simulation examples SLIM can be used to generate entire fields such as the one 0 0 shown in Figures 1a and 1b where 1000s simulations of an HDF-N like field are shown.