| Description |
scientific abstract we propose to survey selected extended regions within the inner 3 x 2 degrees of our galaxy in the 4 to 200 micron wavelength range. from smaller structures, such as the circumnuclear disk, the streamer, some cloud cores, m-0.13-0.08, sgra east, the arc as well as previously catalogued discrete fir sources, we plan to take surface brightness spectra in the same wavelength range. through comparison with model calculations, with existing images from iras, and with images at 2.2 micron and sub-mm wavelength, these observations will provide much detailed information of the morphology, the sources of heating, the intensity of the interstellar radiation field, and the location relative to the galactic centre of the various dust components. a particular goal is to distinguish between the possible star burst and monster nature of the inner few parsecs. observation summary isocam exposures centered on sgr a*: - 1.5 arcsec pfov with the sw4,sw1, sw3, sw8, sw9, sw10, sw5. - 3.0 arcsec pfov with the lw1, lw2, lw3, lw7, lw8. concatenated p05 and p25 1 dimensional rasters: - each raster has 1x32 points with an interval of 3.; the central raster is centered on sgra*; its elongations are displaced by +- 75. in l and b to cover in total +-2 degs in l and b. 7 points are overlapping. p25 from l = +- 2 and b = +- 2 degrees towards sgr a* at 200 microns. p05 from l = +- 2 and b = +- 2 degrees towards sgr a* at 100, 60, 25, 4.85 and 3.6 microns. (raw iras data, which is highly non-linear in the bright central region, will be compared with the p05 scans at 100, 60 and 25 microns to calibrate the iras survey of the central region at these wavelength s). large rasters: 1) raster strip scan with p25 (ny=1, nz=6 at 200 microns and ny=1, nz=7 at 100 and 60 microns, centered 72 east of sgr a*). these are concatinated to p32 raster maps at 200, 100 and 60 microns, centered on the same position. the raster parameters for the p32 are: 200 microns: ny=8, nz=19, o/s=2, tint=8sec ; 100/60 microns: ny=8, nz=11, o/s=2/3, tint=8sec). 2) the same procedure as in 1) applied at the position of the arc. spectral mapping of sgr a east with isophot-s: - p40 13x13 raster with tint = 32s, deltay=deltaz=24 arcsec, centered 72 east of sgr a*. for a spring launch, where the source may not be visible in any one orbit for greater than an hour, we perform this raster as the sum of 7x7, 7x6, 6x7 and 6x6 rasters sampled at 48 arcsec in equatorial coordinates. - 25 microns linear scans in fixed equatorial orientation. small rasters at intemediate wavelengths: - raster strip scan with p25 (ny=1, nz=3 at 135 microns and ny=1, nz=3 at 70 and 50 microns, centered 72 east of sgr a*). these are concatinated to p32 raster maps at 135, 70 and 50 microns, centered on the same position. the raster parameters for the p32 are: 135 microns: ny=4, nz=7, o/s=2, tint=8sec; 70/50 microns: ny=4, nz=5, o/s=2/3, tint=8sec). visibility considerations: the galactic centre is on the edge of a hole in sky visibility for spring launch, and the extent to which it will be visible will de pend critically on the time of night of the launch. therefore, we are only proposing to observe the full program for an autumn launch. for the spring launch we are proposing only the very highest priority of the above observations - the isocam imaging of the central parsecs, the large two dimensional rasters centred 72 arc sec east of sgr a* at 200, 100 and 60 micron - and the pht-s mapping of sgr a east a nd west. |
