<=== observer ===> "ECAUX",\ "Caux, E.",\ "",\ "CESR",\ "",\ "B.P. 4346",\ "31029",\ "Toulouse Cedex",\ "France",\ " 33 61556689",\ " 33 61556701",\ "caux@cesrva.span.cnes.fr" <=== proposal ===> "ISM_IIB", 1, 2,\ {"diffuse interstellar medium","molecular clouds","dust properties",\ "galactic structure"},\ {"LWS consortium","M. Burgdorf","M. Perault"} <=== title ===> STUDY OF THE LOW DENSITY COMPONENTS OF THE ISM THE DIFFUSE MEDIUM IN THE GALACTIC PLANE <=== abstract ===> SCIENTIFIC ABSTRACT This proposal sets out a plan for observation of the diffuse infrared emission spectrum. It concerns both the Zodiacal light emission and the diffuse Galactic emission. These observations have two goals: 1/ to model the diffuse emission elsewhere in the sky to substract it from the source's emission. 2/ to get information about the chemical and physical properties of the dust grains embedded in this diffuse medium and about the thermal balance into the Galaxy, as well as the spatial variation of these properties (with the height above the plane, and with the galactocentric distance). One can define three components of the Galactic diffuse medium : the Cirrus, the HI envelopes of the Giant Molecular Clouds, and the intercloud medium that is mainly composed of HI gas outside well defined HI clouds. The study of the two first components concerns other proposals. This proposal only deals with the last component, the intercloud medium. Another fold of this proposal is the measure of the Zodiacal light spectrum and its variation with Solar elongation and Ecliptic latitude. ISOCAM images, using filters LW 1, 2 and 3, will be taken and will improve the modeling of the sky around the source, providing information on the contribution of discrete sources. OBSERVATION SUMMARY Because the infrared diffuse emission is made of several components (Zodiacal, Galactic and may be Extragalactic), to get the spectrum of the diffuse Galactic component, we will need first a good knowledge of the zodiacal light spectrum, and its variation with ecliptic latitude and Solar elongation. In a first step, we will neglect the maybe existing Extragalactic component. To get only the emission of the diffuse medium, careful analysis of IRAS maps has been made in one hand to find the best lines of sight for these observations, outside emission related to cirrus, molecular clouds as well as HI clouds. For the Zodiacal light study, we propose to observe a set of lines of sight with ISO/LWS to model the intensities and spectral variation of this component. For the Galactic Diffuse emission, we propose to get first the spectrum of the local diffuse medium at a few galactic latitude fields, where Galactic emission related to well-known HI or molecular clouds is minimal. Then, to study the variation of the diffuse emission spectrum with the galactocentric radius R, and also with the height above the Galactic plane z, we propose to get full grating scans for different latitude fields at a few set of Galactic longitudes, outside well known strong sources in or near the Galactic disc and well known nearby high latitude molecular clouds. <=== scientific_justification ===> AOTs The strategy will thus be to take a full grating spectrum for each position. The exposure times are calculated with AOT LWS01 (full grating scan) with 1 sample per resolution element and with the "fast" scanning mode in order to achieve signal to noise ratio between 10 and 60 over the whole spectral range. Zodiacal emission: we propose to observe this emission at ecliptic latitudes of 0, 15, 30, 45, 60 and 90 degrees for both maximum and minimum solar elongation. Galactic emission: we propose to observe the following lines of sight, in galactic coordinates: at l = 30d b = 0, 1, 2, 3, 5 and 10d and b = -1, -2, -3, -5 and -10d at l = 90d b = 0, 1, 2, 3, 5 and 10d and b = -1, -2, -3, -5 and -10d at l = 165d b = 0, 1, 2, 3, 5, 10, 30, 60 and 90d and b = -1, -2, -3, -5, -10, -30, -60 and -90d All the planned lines of sight have been selected from careful analysis of the IRAS maps to be outside the main emission features (cirrus, HI clouds and molecular clouds). For Zodiacal Light observations, no coordinates are specified in the source list, due to the unknown launch date. LINKED OBSERVATIONS WITH ISOCAM (autumn launch only): 12 arcmin away from the pointed observations with LWS images with ISOCAM are taken, using filters LW 2 (in parallel mode) and, at a few selected positions, LW 1 and 3 (as linked observations). The exact positions of these images around those with LWS will depend on the roll angle of the telescope at the time the LWS observations will be done, but since they are part of a survey that will determine the large scale properties of the Galaxy, this kind of uncertainty does not influence the scientific value of the observations. The images in three spectral bands will supplement the observations of the CP proposal "Selected Area Galactic Survey with ISOCAM" (S. Price et al.) and will therefore be shared between the consortia of this and Dr. Price's proposal. They will yield an improvement in modeling the point source sky and will thus provide accurate information on the contribution of discrete sources. During the pointed observations done in this proposal with LWS, ISOCAM LW 2 (5 - 8.5 um), 6" PFOV, parallel mode observations are automatically obtained as by-products. In order to supplement them with ISOCAM images in different filters, some positions of the parallel mode observations are revisited with ISOCAM LW 3 (12 - 17 um) and LW 1 (4 - 5 um), 6" PFOV, as prime instrument. As the positions of the ISOCAM parallel mode images depend on the roll angle of the telescope which is not known in advance, the ISOCAM observations with LW 3 and 1 have to be linked to the pointed LWS observations. The only informations needed in this procedure from the LWS pointed observations are the exact positions of the appertaining ISOCAM parallel observations. They will subsequently be inserted into the target list replacing the current values. In order to distinguish the names of the ISOCAM parallel mode positions from those of the LWS prime observations, they have got the suffix "CAM-||" in the target list. 9 LW 3 and 1 images (in this order) will be taken to match LW 2 observations in parallel mode; only the positions at b = 30 deg, |l| < 10 deg will be revisited. Many other positions are included in the proposal "Diffuse infrared emission of the Galaxy" (K. Mattila et al.). Each entry in the target list takes about 7 minutes with a CAM general observation in two filters; the spacecraft time for these linked CAM observations is therefore 1.1 hours. SPACECRAFT TIME SUMMARY Time distribution for autumn launch targets: Team top 40% second 30% last 30% LWS: 21124 sec 16028 sec 16448 sec SOT: 3960 sec total: 25084 sec Time distribution for spring launch targets: Team top 40% second 30% last 30% LWS: 21292 sec 15988 sec 16976 sec <=== autumn_launch_targets ===> 1, "LWS01",1.0,"N","Zod.Light max 00", 0.0, 0.0,2000,0.,0., 656, 0 2, "LWS01",1.0,"N","Zod.Light max 15", 0.0, 0.0,2000,0.,0., 770, 0 3, "LWS01",1.0,"N","Zod.Light max 30", 0.0, 0.0,2000,0.,0.,1264, 0 4, "LWS01",1.0,"N","Zod.Light max 60", 0.0, 0.0,2000,0.,0.,2312, 0 5, "LWS01",1.0,"N","Zod.Light max 90", 0.0, 0.0,2000,0.,0.,2612, 0 6, "LWS01",2.0,"N","Zod.Light min 15", 0.0, 0.0,2000,0.,0.,1628, 0 7, "LWS01",2.0,"N","Zod.Light max 45", 0.0, 0.0,2000,0.,0.,1628, 0 8, "LWS01",3.0,"N","Zod.Light min 00", 0.0, 0.0,2000,0.,0., 878, 0 9, "LWS01",2.0,"N","Zod.Light min 90", 0.0, 0.0,2000,0.,0.,2612, 0 10,"LWS01",3.0,"N","Zod.Light min 30", 0.0, 0.0,2000,0.,0.,1478, 0 11,"LWS01",3.0,"N","Zod.Light min 45", 0.0, 0.0,2000,0.,0.,1628, 0 12,"LWS01",3.0,"N","Zod.Light min 60", 0.0, 0.0,2000,0.,0.,2312, 0 13,"LWS01",1.0,"N","Gal.Light 165+00",04.98440,+41.77014,1950,0.,0., 528, 0 14,"LWS01",1.0,"N","Gal.Light 165+02",05.15789,+42.47594,1950,0.,0., 528, 0 15,"LWS01",1.0,"N","Gal.Light 165+10",05.80930,+46.59722,1950,0.,0., 528, 0 16,"LWS01",1.0,"N","Gal.Light 165+90",12.81361,+27.40000,1950,0.,0.,4196, 0 17,"LWS01",1.0,"N","Gal.Light 90+00",21.07165,+46.82475,1950,0.,0., 580, 0 18,"LWS01",1.0,"N","Gal.Light 90+02",20.96073,+48.59397,1950,0.,0., 528,19 19,"LWS01",1.0,"N","Gal.Light 90+03",20.92176,+49.88872,1950,0.,0., 348, 0 20,"LWS01",1.0,"N","Gal.Light 90+05",20.81231,+51.63856,1950,0.,0., 542, 0 21,"LWS01",1.0,"N","Gal.Light 90+10",20.26306,+53.12381,1950,0.,0., 732, 0 22,"LWS01",1.0,"N","Gal.Light 60+00",19.71196,+24.19167,1950,0.,0., 458, 0 23,"LWS01",1.0,"N","Gal.Light 60+02",19.54413,+24.03419,1950,0.,0., 528, 0 24,"LWS01",1.0,"N","Gal.Light 60+03",19.48796,+24.74958,1950,0.,0., 580, 0 25,"LWS01",1.0,"N","Gal.Light 60+05",19.42884,+27.38681,1950,0.,0., 656, 0 26,"LWS01",1.0,"N","Gal.Light 60+10",18.98755,+27.00261,1950,0.,0., 694, 0 27,"LWS01",1.0,"N","Gal.Light 30+00",18.65869,-04.57192,1950,0.,0., 458,28 28,"LWS01",1.0,"N","Gal.Light 30+01",18.63167,-03.53500,1950,0.,0., 298,29 29,"LWS01",1.0,"N","Gal.Light 30+02",18.57729,-02.58233,1950,0.,0., 298, 0 30,"LWS01",2.0,"N","Gal.Light 30+03",18.56412,-00.86097,1950,0.,0., 458, 0 31,"LWS01",1.0,"N","Gal.Light 30+05",18.41393,-00.79525,1950,0.,0., 488, 0 32,"LWS01",1.0,"N","Gal.Light 30+10",18.17765,+03.25961,1950,0.,0., 542, 0 33,"LWS01",2.0,"N","Gal.Light 30-03",18.96392,-02.27694,1950,0.,0., 478, 0 34,"LWS01",2.0,"N","Gal.Light 165+01",05.11861,+41.30575,1950,0.,0., 528, 0 35,"LWS01",2.0,"N","Gal.Light 165-02",04.79116,+41.17231,1950,0.,0., 542, 0 36,"LWS01",2.0,"N","Gal.Light 165+03",05.19567,+43.64636,1950,0.,0., 542, 0 37,"LWS01",2.0,"N","Gal.Light 165+05",05.44358,+42.85956,1950,0.,0., 542, 0 38,"LWS01",2.0,"N","Gal.Light 165-03",04.72421,+40.53678,1950,0.,0., 528, 0 39,"LWS01",2.0,"N","Gal.Light 165-30",03.32034,+20.38422,1950,0.,0., 508, 0 40,"LWS01",2.0,"N","Gal.Light 165+60",10.94925,+48.00875,1950,0.,0., 694, 0 41,"LWS01",3.0,"N","Gal.Light 90+01",21.02880,+47.84369,1950,0.,0., 542, 0 42,"LWS01",2.0,"N","Gal.Light 90-02",21.38322,+47.48569,1950,0.,0., 656, 0 43,"LWS01",2.0,"N","Gal.Light 90-05",21.52494,+44.72781,1950,0.,0., 694, 0 44,"LWS01",2.0,"N","Gal.Light 90-10",21.93640,+41.85889,1950,0.,0., 694, 0 45,"LWS01",3.0,"N","Gal.Light 60+01",19.66786,+25.16072,1950,0.,0., 488, 0 46,"LWS01",2.0,"N","Gal.Light 60-02",19.80722,+22.35292,1950,0.,0., 528, 0 47,"LWS01",2.0,"N","Gal.Light 60-05",20.05239,+22.22619,1950,0.,0., 618, 0 48,"LWS01",2.0,"N","Gal.Light 60-10",20.29389,+18.27897,1950,0.,0., 656, 0 49,"LWS01",2.0,"N","Gal.Light 30-02",18.91113,-01.63244,1950,0.,0., 458, 0 50,"LWS01",2.0,"N","Gal.Light 30-05",18.94223,-07.26006,1950,0.,0., 508, 0 51,"LWS01",2.0,"N","Gal.Light 30-10",18.33029,-06.93972,1950,0.,0., 528, 0 52,"LWS01",3.0,"N","Gal.Light 165-01",04.97116,+40.24900,1950,0.,0., 528, 0 53,"LWS01",3.0,"N","Gal.Light 165-05",04.63597,+38.66650,1950,0.,0., 528, 0 54,"LWS01",3.0,"N","Gal.Light 165-60",02.22862,-05.27556,1950,0.,0., 542, 0 55,"LWS01",3.0,"N","Gal.Light 165-90",00.81667,-27.40000,1950,0.,0.,4196, 0 56,"LWS01",3.0,"N","Gal.Light 90-01",21.22122,+47.19147,1950,0.,0., 580, 0 57,"LWS01",3.0,"N","Gal.Light 90-03",21.46029,+46.88017,1950,0.,0., 694, 0 58,"LWS01",3.0,"N","Gal.Light 60-01",19.76241,+23.25714,1950,0.,0., 488, 0 59,"LWS01",3.0,"N","Gal.Light 60-03",19.81581,+20.62631,1950,0.,0., 580, 0 60,"LWS01",3.0,"N","Gal.Light 30-01",18.72050,-04.97408,1950,0.,0., 458, 0 61,"CAM01",1.0,"N","G.L.-CAM-||30-05",18.94223,-07.26006,1950,0.,0., 440, 0 62,"CAM01",1.0,"N","G.L.-CAM-||30-03",18.96392,-02.27694,1950,0.,0., 440, 0 63,"CAM01",1.0,"N","G.L.-CAM-||30-02",18.91113,-01.63244,1950,0.,0., 440, 0 64,"CAM01",1.0,"N","G.L.-CAM-||30-01",18.72050,-04.97408,1950,0.,0., 440, 0 65,"CAM01",1.0,"N","G.L.-CAM-||30+00",18.65869,-04.57192,1950,0.,0., 440, 0 66,"CAM01",1.0,"N","G.L.-CAM-||30+01",18.63167,-03.53500,1950,0.,0., 440, 0 67,"CAM01",1.0,"N","G.L.-CAM-||30+02",18.57729,-02.58233,1950,0.,0., 440, 0 68,"CAM01",1.0,"N","G.L.-CAM-||30+03",18.56412,-00.86097,1950,0.,0., 440, 0 69,"CAM01",1.0,"N","G.L.-CAM-||30+05",18.41393,-00.79525,1950,0.,0., 440, 0 <=== spring_launch_targets ===> 1, "LWS01",1.0,"N","Zod.Light max 00", 0.0, 0.0,2000,0.,0., 656, 0 2, "LWS01",1.0,"N","Zod.Light max 15", 0.0, 0.0,2000,0.,0., 770, 0 3, "LWS01",1.0,"N","Zod.Light max 30", 0.0, 0.0,2000,0.,0.,1264, 0 4, "LWS01",1.0,"N","Zod.Light max 60", 0.0, 0.0,2000,0.,0.,2312, 0 5, "LWS01",1.0,"N","Zod.Light max 90", 0.0, 0.0,2000,0.,0.,2612, 0 6, "LWS01",2.0,"N","Zod.Light min 15", 0.0, 0.0,2000,0.,0.,1628, 0 7, "LWS01",2.0,"N","Zod.Light max 45", 0.0, 0.0,2000,0.,0.,1628, 0 8, "LWS01",3.0,"N","Zod.Light min 00", 0.0, 0.0,2000,0.,0., 878, 0 9, "LWS01",2.0,"N","Zod.Light min 90", 0.0, 0.0,2000,0.,0.,2612, 0 10,"LWS01",3.0,"N","Zod.Light min 30", 0.0, 0.0,2000,0.,0.,1478, 0 11,"LWS01",3.0,"N","Zod.Light min 45", 0.0, 0.0,2000,0.,0.,1628, 0 12,"LWS01",3.0,"N","Zod.Light min 60", 0.0, 0.0,2000,0.,0.,2312, 0 13,"LWS01",1.0,"N","Gal.Light 165+00",04.98440,+41.77014,1950,0.,0., 528, 0 14,"LWS01",1.0,"N","Gal.Light 165+02",05.15789,+42.47594,1950,0.,0., 528, 0 15,"LWS01",1.0,"N","Gal.Light 165+10",05.80930,+46.59722,1950,0.,0., 528, 0 16,"LWS01",1.0,"N","Gal.Light 165+30",07.77368,+53.47972,1950,0.,0., 656, 0 17,"LWS01",1.0,"N","Gal.Light 165+90",12.81361,+27.40000,1950,0.,0.,4196, 0 18,"LWS01",1.0,"N","Gal.Light 90+00",21.07165,+46.82475,1950,0.,0., 580, 0 19,"LWS01",1.0,"N","Gal.Light 90+02",20.96073,+48.59397,1950,0.,0., 528,20 20,"LWS01",1.0,"N","Gal.Light 90+03",20.92176,+49.88872,1950,0.,0., 348, 0 21,"LWS01",1.0,"N","Gal.Light 90+05",20.81231,+51.63856,1950,0.,0., 542, 0 22,"LWS01",1.0,"N","Gal.Light 90+10",20.26306,+53.12381,1950,0.,0., 732, 0 23,"LWS01",1.0,"N","Gal.Light 60+00",19.71196,+24.19167,1950,0.,0., 458, 0 24,"LWS01",1.0,"N","Gal.Light 60+02",19.54413,+24.03419,1950,0.,0., 528, 0 25,"LWS01",1.0,"N","Gal.Light 60+03",19.48796,+24.74958,1950,0.,0., 580, 0 26,"LWS01",1.0,"N","Gal.Light 60+05",19.42884,+27.38681,1950,0.,0., 656, 0 27,"LWS01",1.0,"N","Gal.Light 60+10",18.98755,+27.00261,1950,0.,0., 694, 0 28,"LWS01",1.0,"N","Gal.Light 30+00",18.65869,-04.57192,1950,0.,0., 458,29 29,"LWS01",1.0,"N","Gal.Light 30+01",18.63167,-03.53500,1950,0.,0., 298,30 30,"LWS01",1.0,"N","Gal.Light 30+02",18.57729,-02.58233,1950,0.,0., 298, 0 31,"LWS01",2.0,"N","Gal.Light 30+03",18.56412,-00.86097,1950,0.,0., 458, 0 32,"LWS01",2.0,"N","Gal.Light 30+05",18.41393,-00.79525,1950,0.,0., 488, 0 33,"LWS01",1.0,"N","Gal.Light 30+10",18.17765,+03.25961,1950,0.,0., 542, 0 34,"LWS01",2.0,"N","Gal.Light 30-03",18.96392,-02.27694,1950,0.,0., 478, 0 35,"LWS01",3.0,"N","Gal.Light 165+01",05.11861,+41.30575,1950,0.,0., 528, 0 36,"LWS01",2.0,"N","Gal.Light 165-02",04.79116,+41.17231,1950,0.,0., 542, 0 37,"LWS01",3.0,"N","Gal.Light 165+03",05.19567,+43.64636,1950,0.,0., 542, 0 38,"LWS01",2.0,"N","Gal.Light 165+05",05.44358,+42.85956,1950,0.,0., 542, 0 39,"LWS01",2.0,"N","Gal.Light 165-10",05.70644,+09.71986,1950,0.,0., 528, 0 40,"LWS01",2.0,"N","Gal.Light 165-30",03.32034,+20.38422,1950,0.,0., 508, 0 41,"LWS01",2.0,"N","Gal.Light 165+60",10.94925,+48.00875,1950,0.,0., 694, 0 42,"LWS01",2.0,"N","Gal.Light 90+01",21.02880,+47.84369,1950,0.,0., 542, 0 43,"LWS01",2.0,"N","Gal.Light 90-02",21.38322,+47.48569,1950,0.,0., 656, 0 44,"LWS01",2.0,"N","Gal.Light 90-05",21.52494,+44.72781,1950,0.,0., 694, 0 45,"LWS01",2.0,"N","Gal.Light 90-10",21.93640,+41.85889,1950,0.,0., 694, 0 46,"LWS01",3.0,"N","Gal.Light 60+01",19.66786,+25.16072,1950,0.,0., 488, 0 47,"LWS01",2.0,"N","Gal.Light 60-02",19.80722,+22.35292,1950,0.,0., 528, 0 48,"LWS01",2.0,"N","Gal.Light 60-05",20.05239,+22.22619,1950,0.,0., 618, 0 49,"LWS01",2.0,"N","Gal.Light 60-10",20.29389,+18.27897,1950,0.,0., 656, 0 50,"LWS01",2.0,"N","Gal.Light 30-02",18.91113,-01.63244,1950,0.,0., 458, 0 51,"LWS01",2.0,"N","Gal.Light 30-05",18.94223,-07.26006,1950,0.,0., 508, 0 52,"LWS01",2.0,"N","Gal.Light 30-10",18.33029,-06.93972,1950,0.,0., 528, 0 53,"LWS01",3.0,"N","Gal.Light 165-01",04.97116,+40.24900,1950,0.,0., 528, 0 54,"LWS01",3.0,"N","Gal.Light 165-03",04.72421,+40.53678,1950,0.,0., 528, 0 55,"LWS01",3.0,"N","Gal.Light 165-05",04.63597,+38.66650,1950,0.,0., 528, 0 56,"LWS01",3.0,"N","Gal.Light 165-60",02.22862,-05.27556,1950,0.,0., 542, 0 57,"LWS01",3.0,"N","Gal.Light 165-90",00.81667,-27.40000,1950,0.,0.,4196, 0 58,"LWS01",3.0,"N","Gal.Light 90-01",21.22122,+47.19147,1950,0.,0., 580, 0 59,"LWS01",3.0,"N","Gal.Light 90-03",21.46029,+46.88017,1950,0.,0., 694, 0 60,"LWS01",3.0,"N","Gal.Light 60-01",19.76241,+23.25714,1950,0.,0., 488, 0 61,"LWS01",3.0,"N","Gal.Light 60-03",19.81581,+20.62631,1950,0.,0., 580, 0 62,"LWS01",3.0,"N","Gal.Light 30-01",18.72050,-04.97408,1950,0.,0., 458, 0