We have assessed how well stellar parameters ( T _ { eff } , \log g and [ M/H ] ) can be retrieved from low-resolution dispersed images to be obtained by the DIVA satellite .
Although DIVA is primarily an all-sky astrometric mission , it will also obtain spectrophotometric information for about 13 million stars ( operational limiting magnitude V \simeq 13.5 mag ) .
Constructional studies foresee a grating system yielding a dispersion of \simeq 200nm/mm on the focal plane ( first spectral order ) .
For astrometric reasons there will be no cross dispersion which results in the overlapping of the first to third diffraction orders .
The one-dimensional , position related intensity function is called a dispi ( DISP ersed I ntensity ) .
We simulated dispi s from synthetic spectra taken from ( ) and ( ) but for a limited range of metallicites , i.e .
our results are for [ M/H ] in the range - 0.3 to 1 dex .
We show that there is no need to deconvolve these low resolution signals in order to obtain basic stellar parameters .
Using neural network methods and by including simulated data of DIVA ’ s UV telescope , we can determine T _ { eff } to an average accuracy of about 2 % for dispi s from stars with 2000 K \leq T _ { eff } \leq 20000 K and visual magnitudes of V = 13 mag ( end of mission data ) . \log g can be determined for all temperatures with an accuracy better than 0.25 dex for magnitudes brighter than V = 12 mag .
For low temperature stars with 2000 K \leq T _ { eff } \leq 5000 K and for metallicities in the range - 0.3 to +1 dex a determination of [ M/H ] is possible ( to better than 0.2 dex ) for these magnitudes .
For higher temperatures , the metallicity signatures are exceedingly weak at dispi resolutions so that the determination of [ M/H ] is there not possible .
Additionally we examined the effects of extinction E ( B - V ) on dispi s and found that it can be determined to better than 0.07 mag for magnitudes brighter than V = 14 mag if the UV information is included .