... The J, H and K bands are characterized by a bright background, such a background is mainly due to the emission of atmospheric lines and of thermal radiation. ... If the source cover a large fraction of the slit, spectra off-source must be observed to adequately sample the sky background. ... The on chip integration time (time spent in each position of the slit) must not exceed 40 seconds in J and H bands and 60 seconds in K band. ... We suggest a sequence of 10 for each elementary integration time. ...

Next: *imcalc* - Obtain a Up: Calibration Previous: Exposure Map . Background maps are provided by the standard processing for all ROSAT and Einstein instruments. For the PSPC and IPC these are in three standard bands: soft, hard, and broad (Table 6.2). ... N.B.: ROSAT PSPC background maps in SASS 5-6 or higher are generated by smoothing a source-subtracted, exposure corrected image (see the ROSAT Data Products Guide). ... imcalc* - Obtain a background subtracted image for ROSAT PSPC Data . ...

STIS Instrument Handbook for Cycle 24 . ... Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 24 > Chapter 12: Special Uses of STIS > 12.1 Slitless First-Order Spectroscopy . ... Slitless First-Order Spectroscopy . ... The use of a long slit ensures a clean separation of emission lines arising from different spatial features. ... Figure 4.8 shows an image of SN1987A observed using the 52X2 aperture, and as the source is smaller than the slit, this is effectively a slitless image. ...

... rgsspectrum creates an OGIP-compliant spectrum of counts for a single RGS exposure. ... background-corrected source spectrum . ... Note that although the spatial selection region for the background spectrum is not source-specific, the energy selection region is source-specific, and for this reason the background spectrum is technically source-specific. ... The above description of the BACKSCAL column applies only to Spectroscopy mode data; in HTR mode this column has nothing to do with exposure. ...