... The accuracy to which you can trust the absolute flux calibration of your STIS spectroscopic data at slit center is limited by several factors including: . The accuracy of the absolute sensitivity calibration of the grating and central wavelength setting. ... The STIS spectrum of this star is then extracted over a standard aperture extraction box and the sensitivity required to return the known flux from the star is determined as a function of wavelength. ...

Next: *imcnts* - Radial Profile Up: Radial Profiles and Projections Previous: *tabplot* - Displaying a . ... Input a spatially blocked and energy filtered image from above and use with the background determined from the broad-band background map. cl xray xr xspatial xs imcnts addbkg=no # Do not add the background error Source image file : xdata$snr.qp Source region descripter: c 503 513 50 p 503 513 0 360 n=10 # circular region centered on point ...

Next: Analysis Tools for Nebular Emission Lines . ... Extracting spectra from a large number of NICMOS grism images requires a convenient interactive tool which allows a user to manipulate direct/grism image pairs. ... The direct image is used to locate objects of interest, to find the position of the appropriate spectra in the grism image, to determine the optimal extraction technique to use, and to calibrate the wavelength range of the extracted spectra. ... Figure 1: The NICMOSlook User Interface . ...

... By default the task will reduce the effective area produced in the ARF if the source area contains bad pixels/columns or contains area which lies outside the CCD boundaries. ... Although the correction for point sources is quite good the extended source correction assumes a uniform surface brightness of the source. ... There is currently no way of performing an accurate correction for chip gaps and bad pixels within extended source regions within arfgen . ...

This page was created by the IDL library routine mk_html_help . ... mk_html_help . at the IDL command line prompt. ... to calculate CHIANTI line intensities and continua, to create a synthetic spectrum. ... WRITTEN : Ver.1, 7-Nov-01, Giulio Del Zanna (GDZ) and Peter Young (PRY) MODIFICATION HISTORY: V.2, 7-Nov-01, GDZ . Fixed a small bug (now the spectrum plot is always plotted within the widget), and modified the option to add continua. ... Added extended details in the ascii output spectrum. ...

Next: Imaging Polarimetry with NICMOS Up: NICMOS Data Calibration and Previous: The Photometric Performance of . ... NICMOSlook and Calnic C . ... Extracting spectra from a large number of NICMOS grism images requires a convenient interactive tool which allows a user to manipulate direct/grism image pairs. ... NICMOSlook and Calnic-C are two programs that were designed to take advantage of the fact that the NICMOS grism mode typically consists of taking both a direct and a grism image. ...

Next: Airmass Calculation Up: Flux Calibration Previous: Flux Calibration . To calibrate the chromatic response, observations of a standard star (preferably more than one) are needed, for which the absolute fluxes are known. The spectral response curve of the instrument can then be determined with the command RESPONSE/LONG , and absolute fluxes for the objects of interest are obtained with CALIBRATE/FLUX . ...

... User Guide ] Task: gpnorm Purpose: Correct the polarisation leakage terms for an offset. Categories: calibration GpNorm is a MIRIAD task which corrects gains and polarisation leakage tables for XYphase and leakage offsets. ... GpNorm compares the leakage terms with nominally correct terms, and determines an leakage and XY phase offset to add which will minimise the difference between the two sets of leakages. ... No default. Key: cal The data-set containing the nominally correct leakage table. ...

ALMA | ... Phase Correction Algorithms | ... On this page, we describe what the phase correction algorithms set out to do and the framework we have developed to optimally use all of the available information. ... We are developing a Bayesian framework to combine all the information we have about the current and future meterological conditions (which are naturally accommodated as priors in a Bayesian scheme) with detailed physical models of the atmosphere. ...

These are very prominent absorption lines is most all galaxies. ... These pair of absorption lines will appear in all the spectra and they should be your principle source for determining the redshift. ... When this applet opens you will see an iconic representation of galaxies in the left hand side of the applet and a target area in the right side of the applet. ... Note: What you are doing in this excercise is identical to what Hubble did in the 1920's and you are using the same galaxies. ...

... We cannot use for this purpose equivalent widths and profiles of HI lines (well known criteria of atmospheric conditions for normal supergiants), since these lines are strongly distorted in the spectrum of IRAS04296 as seen in Fig. ... Figure: Upper: iron abundance FeI (circles) and FeII (crosses) calculated for IRAS04296+3429 with model parameters , and using lines with different excitation potentials EP of a low level; bottom: the same as a function of the equivalent width W . ...