scientific abstract comets are believed to retain most of the original content of the pristine solar nebula. therefore, their study provides a unique way to understand the history of our solar system and its relation to the interstellar medium. we propose to observe one or two periodic comets within the iso central program. the primary goals are to investigate the dust and gas compositions of these objects, to probe the molecular excitation mechanisms and the coma physical conditions, to monitor the cometary activity and outgassing processes as a function of heliocentric distance, to compare the behaviour of different objects. the present program concentrates on medium-resolution spectroscopic observations with lws and sws. we propose to observe reference spectra of the brightest objects in the full spectral range of lws and sws. observations of specific spectral ranges dedicated to the water, co2 and co bands are also planned. for a launch in nov. 1995, the most suitable periodic comet during iso.s planned life seems to be p/kopff, which we plan to observe at different periods to study its evolution. in the case of a launch in may 1996, an additional target is p/wild 2. this proposal is complementary to other cp cometary proposals to be done with cam and pht. observation summary cometary observations are highly time-dependent. the following targets and observing periods were selected in function of the expected comet activity and of the instrument sun and earth constraints. target list and special requirements: for a launch in autumn 1995: - p/kopff in apr. 1996 (best period before perihelion: delta = 1.1 au, rh = 1.8 au; expected q[gas] = 4.e28 s-1). (#1-7.) - p/kopff in oct. 1996 (best period after perihelion: delta = 1.2 au, rh = 1.9 au; expected q[gas] = 4.e28 s-1). (#8-14.) - p/kopff in dec. 1996 (repeated observation at a larger heliocentric distance to see evolution). (#15-17.) for a launch i...n spring 1996: - p/kopff in oct. 1996 (best period after perihelion: delta = 1.2 au, rh = 1.9 au; expected q[gas] = 4.e28 s-1). (#1-7.) - p/wild 2 in apr. 1997 (best period around perihelion: delta = 1.1 au, rh = 1.6 au; expected q[gas] = 3.e28s-1). (#8-14.) - p/kopff in dec. 1996 (repeated observation at a larger heliocentric distance to see evolution). (#16-17.) spectra to be observed: - reference spectra of the full 47-197 micron region with the lws grating. we expect to mesure several water rotational lines to probe the excitation conditions, and to detect several oh lines. the observations will be made in two parts: one integration on the comet, another one on the same field one or several days later when the comet has moved (shadow), to get the background continuum. (#1 & 3, 8 & 10, 15 & 16.) - reference spectra of the full 2.4-45 micron region with the sws grating. (#5 & 6 & 7, 12 & 13 & 14.) - sws grating spectra of the 2.600-2.898 micron region: study of the water bands and of the 2.8 micron unidentified cometary emission. (#2, 9.) - sws grating spectra of the 4.051-4.805 micron region: study of the co2 bands and search for co and other species. (#4, 11, 17.)
Instrument
CAM01 , CAM04 , LWS01 , PHT40 , SWS02 , SWS06
Temporal Coverage
1996-02-10T18:35:55Z/1998-04-06T17:23:04Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, 1999, Spectroscopic Observations Of Periodic Comets With Lws And Sws. , 1.0, European Space Agency, https://doi.org/10.5270/esa-gikcgg7
