Absolute Flux Calibration for STIS First-Order, Low-Resolution Modes
|
|
- Annice Beasley
- 5 years ago
- Views:
Transcription
1 Instrument Science Report STIS Absolute Flux Calibration for STIS First-Order, Low-Resolution Modes Ralph Bohlin, Space Telescope Science Institute Nicholas Collins, Hughes STX/LASP/GSFC Anne Gonnella, Space Telescope Science Institute February 1998 ABSTRACT Point source sensitivity curves are derived for the first order modes G140L, G230L, G230LB, G430L, and G750L, which collectively span a wavelength range from 1140Å to 10320Å. The curves are determined by comparing wide slit (52" x 2") observations of the spectrophotometric standard star GD153 to a pure hydrogen white dwarf model. The calibration is checked by comparing a calibrated STIS observation of the spectrophotometric standard star G191B2B to its pure hydrogen model. Except for G140L, there is no good evidence for changes in the sensitivity beyond ~1% through the end of Except for the G140L and the long wavelength part of G750L, the absolute flux calibration is accurate for observations in 1997 to ~3% for stars centered in the 52x2" slit. Preliminary results on the vignetting analysis for the first order modes suggest that the smooth changes in sensitivity as a function of distance along the slit are less than ±2 % for all first order modes, except for the extremities of G140L, where 5% differences in detector QE are observed. While the 52x2" slit is ideal for photometric continuum determinations, a narrower slit should be used for line profile measurements in order to minimize the contamination from the impure light in the wings of the PSF. For the narrowest slits, local inhomogeneities in the slit width cause a variable throughput along the slit (see the STIS Foibles page on the STIS Instrument WWW pages). 1. Introduction A sensitivity curve, i.e. an absolute flux calibration, is used to determine the flux of an observed point-source spectrum by F = C / S 1
2 where F is the calibrated absolute flux spectrum, C is the observed spectrum in counts pixel -1 second -1, and S is the sensitivity as a function of wavelength (Bohlin, Lindler, & Keyes 1995). The sensitivity is derived by S = C std / F std where C std is the countrate spectrum of a spectrophotometric standard star F std is the known absolute flux spectrum of the same standard in erg cm -2 s -1 Å -1. The pixel in the units for C refers to the dispersion direction, while the point source response is integrated over a fixed extraction height in the cross-dispersion direction on a two-dimensional detector. Before the 1998 February delivery of these throughputs that are based on in-flight observations, the STScI CALSTIS pipeline utilized pre-launch estimates in the photometric throughput tables to flux calibrate data. When the rootname_sx2 files for low resolution first order data calibrated with the prelaunch estimates are used to find the stellar flux as described in the Data Handbook (page 23-5 version 3.0) or when a point source spectrum is extracted from the flat fielded data with the X1D IRAF task, the fluxes are generally within a factor of 1.5 of the correct fluxes. For accurate fluxes, GO s should recalibrate their data (X2D or X1D IRAF tasks) using the latest reference files. 2. STIS Observations Observations of the pure hydrogen white dwarf GD153 (Bohlin, Colina, & Finley 1995) are used to define the sensitivity curve, since these data are the only set of observations of a fundamental standard in all five low-resolution spectral modes. GD153 is a preferred calibration standard, because the only lines are from HI and because Bohlin (1996) defined the FOS calibration with a set of four pure hydrogen WD models that includes GD153. An input spectrum with many lines can confuse the derivation of a sensitivity curve, if the reference spectral line profiles do not perfectly match those of the observed spectrum. All input spectra were obtained using the clear 52"x2" aperture. Relative transmission corrections are required to compute absolute fluxes for other apertures. Two observations comprise the average input spectrum for the far-uv MAMA mode G140L. Only one near-uv (G230L) observation of GD153 exists in the 52x2 aperture. For each of the three CCD modes (G230LB, G430L, and G750L), seven observations obtained at the end of SMOV produce high signal-to-noise average spectra. The position of these seven spectra repeated to 1 pixel on the CCD; and the full range of scatter of relative response is better than 1% in broad bands. However, spectra obtained at other times and at non-standard locations on the CCD show an additional scatter of 1 2%. The component spectra that make up the average spectrum for each mode are listed in Table 1; and 2
3 the spectral extraction heights are 11 pixels for G140L and G230L, and 7 pixels for G230LB, G430L, and G750L (Leitherer & Bohlin 1997). The background is extracted 300 pixels above and below the spectrum and is typically much less than 1% of the continuum signal. Each of the seven component G750L spectra is corrected for the long wavelength CCD fringing with a tungsten flat obtained in the 0.3x0.09 slit. This correction starts with the extracted 1-D spectrum of the tungsten lamp for the three observation that have a 0.3x0.09 contemporaneous flat, O3TT46040, O3TT47040, and O3TT The average of these three spectra is normalized to unity with a spline fit; the amplitude of the fringes longward of 6620 Å is reduced by 11%; an offset shift with respect to each stellar spectrum is computed; and this shifted 1-D tungsten flat is divided into each 1-D spectrum of the star. Below 6620 Å, the tungsten flat is set to unity, since the noise level is worse when the average flat is applied. This procedure works, because all of the seven GD153 spectra lie within a pixel of the same location on the CCD. However, the noise level for the earliest of the seven, O3TT42040, is larger than for the other six, so that the final average GD153 spectrum for G750L is composed of only six observations. Details of the general applicability of this procedure, including a quantitative comparison with alternative techniques will be presented in a fringe ISR. 3
4 Table 1. Observations with 52x2 arcsec slit Rootname Observation Date Target Optical Element Exposure Time (sec) Mean Counts px -1 Prop ID O43J01QAM 09/07/97 GD153 G140L O3ZX08HHM 13/07/97 GD153 G140L O3ZX08HLM 13/07/97 GD153 G230L O3TT /05/97 GD153 G230LB , O3TT /05/97 GD153 G230LB , O3TT /06/97 GD153 G230LB , O3TT /06/97 GD153 G230LB , O3TT /06/97 GD153 G230LB , O3TT /06/97 GD153 G230LB , O3TT /07/97 GD153 G230LB , O3TT /05/97 GD153 G430L , O3TT /05/97 GD153 G430L , O3TT /06/97 GD153 G430L , O3TT /06/97 GD153 G430L , O3TT /06/97 GD153 G430L , O3TT /06/97 GD153 G430L , O3TT /07/97 GD153 G430L , O3TT /05/97 GD153 G750L , O3TT /06/97 GD153 G750L , O3TT /06/97 GD153 G750L , O3TT /06/97 GD153 G750L , O3TT /06/97 GD153 G750L , O3TT /07/97 GD153 G750L ,
5 3. Reference Standard Star Flux The reference spectrum, GD153_MOD_002, is a pure hydrogen white dwarf model normalized to Landolt s visual photometry (Bohlin 1996). The spectrum can be obtained from the Calibration Data Base System (CDBS) at: astronomical_catalogs_alt.html 4. Sensitivity Results For each optical mode, the reference spectrum is integrated to match the resolution of each co-added observation and is then divided into the observed spectrum to produce a sensitivity curve in units of counts pixel 1 second ergs second 1 cm 2 Å 1 At the shortest wavelengths of each mode, the sensitivity drops rapidly with wavelength, so that the uncertainty in the flux calibration in dominated by uncertainties in wavelength. In order to derive the proper sensitivity calibration, the wavelength scale must be as observed in the instrumental frame of rest, i.e., with NO velocity correction. The standard star model spectrum must be shifted to coincide with the observations, i.e., the reference spectrum wavelength scale must be shifted by the radial velocity of the star plus the heliocentric correction for the earth and HST velocity vectors. Consequently, the application of derived sensitivity curves must be to the counts/sec with the instrumental rest frame wavelengths. The observed radial velocity of G191B2B is +22 km/s, which includes the gravitational component (Reid & Wegner, 1988), while a value of km/s for GD153 is estimated from the STIS observations of the Balmer lines. From the proper motion and the photometric distance of 77 pc, Finley (private communication) calculates a tangential velocity of 73 km/s for GD153. Splines with evenly spaced nodes are fit to each ratio in order to obtain a smooth sensitivity curve. Each fit is refined by adding nodes at wavelengths where the slope is large. Table 2 lists the number of nodes and the nominal wavelength range for each mode. The wavelength region 1200 Å 1225 Å in mode G140L is masked to exclude the residuals at the strong Ly α feature from the fit. Small residuals at the Balmer lines on G430L and G750L are caused by slight differences in resolution between STIS and the model spectrum. The sensitivity curves and their residuals are shown in Figures 1 and 2. The spline fits are represented by the dashed line in each plot, while the spline nodes are plotted with diamonds. The large residual at Ly α is caused by neighboring continuum light in the far 5
6 wings of the PSF. Figure 3 is a plot of this line, where the model line profile (smooth solid line) agrees well with FOS observations (dashed line). However, the central depth of the line in the STIS spectrum (heavy jagged solid line) is about 10% higher in units of the continuum. Except at wavelengths beyond ~8500Å where there is considerable scattering within the substrate of the CCD, the scattered light level shown in Figure 3 approaches a worst case, because the PSF from the OTA has more energy in the wings from the microroughness of the mirrors, because the effect of the voltage on the repeller wire in the FUV MAMA is to add signal to the PSF wings, and because the wide 2" slit includes the OTA PSF wings. See Figure 6 in Leitherer & Bohlin (1997) for plots of the STIS PSF in the direction perpendicular to the dispersion. Since the fit in Figure 1 ignores this contaminating light, the shape of the sensitivity curve in the 1216Å region is the same as a pointsource continuum calibration based on a STIS spectrum corrected for the impure light. However, at wavelengths shortward of ~1160Å and at the short wavelength cutoff of G230L, out-of-band light dominates the observed spectrum and makes absolute fluxes unreliable. Out-of-band light is substantially reduced with the 0.2" and smaller slits. Additional data are required to quantify the impure light vs. slit width relation and guide the GO in choosing the right slit width for measuring line profiles and equivalent widths. A subsequent ISR will discuss the choice of the optimum slit in detail; and in the interim, GOs are directed to the STIS Foibles page on the STIS WWW page for the latest information. Preliminary results on the vignetting analysis for the first order modes suggest that the smooth changes in sensitivity as a function of distance along the slit are less than ±2 % for all first order modes, except for the extremities of G140L, where ±5% differences in detector QE are observed. While the 52x2" slit is ideal for photometric continuum determinations, a narrower slit should be used for line profile measurements in order to minimize the contamination from the impure light in the wings of the PSF. For the narrower slits, local inhomogeneities in the slit width can cause a variable throughput along the slit (e.g., see the STIS Foibles page on the STIS Instrument WWW pages). 5. Uncertainties The residuals shown in Figures 1 and 2 are determined by dividing each curve by its spline fit and are plotted for the wavelength ranges listed in Table 2. Table 2 lists the percent root-mean-square residuals averaged over all wavelengths for each mode. Average RMS residuals are listed for three wavelength ranges for mode G750L to show how the scatter increases in the long wavelength region, where fringing is the worst. Unless a peakup is done in a small aperture, pointing errors can cause wavelength errors of up to a pixel (~2-3 σ) on the MAMAs and up to a half pixel on the CCDs. The error in absolute fluxes that is caused by wavelength errors depends of the slope of the sensitivity curve vs. wavelength but can be over a percent near the steep sensitivity cutoffs, 6
7 Table 2. Nodes and Average Percent RMS Deviation for Each Mode Optical Element Wavelength Range (Å) Spline Nodes Avg σ rms G140L , a G230L G230LB G430L G750L b 0.44 G750L G750L a. Residuals in the region of the strong Ly α feature ( Å) are not included in the computation of σ rms. b. Number of nodes for full G750L wavelength range. for example below ~1200Å on G140L. If no wavecal spectrum is taken with the data before moving the Mode Select Mechanism, wavelength errors of a few pixels are possible because of MSM repeatability limits. Wavelength errors can often be corrected, using the stellar radial velocity and a spectral feature of known wavelength in the data spectrum. In general, wavelength uncertainties and the counting statistics of the calibration observations, result in negligible errors in the smooth STIS sensitivities derived here for the 1997 epoch. Uncertainties in the absolute sensitivities are dominated by systematic uncertainties in the reference stellar spectra, which are based on model atmosphere calculations for pure hydrogen WDs (Bohlin, Colina, and Finley 1995). Assuming no error in the model atmosphere calculation, the uncertainty is determined by the shape of the model spectrum vs. wavelength and by the normalization to the V magnitudes of Landolt, as explained in (Bohlin, Colina, and Finley 1995). To recap: Landolt photometry is repeatable to 1σ of ~0.004 mag. Allowing for some uncertainty in the normalization of a flux distribution by the broadband V filter photometry, the reference standard star spectra and derived STIS calibration should be accurate to ~1% (1σ) in the V band wavelength region. Additional uncertainty at other wavelengths is introduced by uncertainty in the continuum slope of the model spectrum, which is dominated by uncertainty in the temperature of the model. For the worst case of GD71 at 1150Å, the formal 1σ uncertainty is 0.35% due to the temperature uncertainty of 100K. The main uncertainty in the physics is the Hummer- Mihalas occupation probability formalism, which causes uncertainties of up to 1% between the Balmer lines. So an assignment of 1σ=1% to flux uncertainties that are caused by slope error is conservative and leads to to a formal 3σ=4% uncertainty outside the V band region and 3% at Å. Future revisions to the STIS flux calibration 7
8 should be based on three stars, instead of just GD153, so that the uncertainties would be formally reduced by a factor of 1.7. There is no evidence for changes in the sensitivity or scatter in the STIS spectrophotometry beyond ~1% through the end of 1997, except for G140L where initial results suggest a drop in sensitivity by up to 7% per year. Fringing in the CCD limits photometric precision to ~2% longward of 8500Å. By mid-1998, the sensitivity monitoring observations should be sufficient to more precisely quantify any changes in sensitivity. 6. Application of the Sensitivity Curves to Observations of G191B2B Figures 4a-c show the residuals of STIS fluxes of GD153 and G191B2B calibrated with the sensitivity curves described in this paper. The comparison is with the standard star models from Bohlin (1996). Residuals for the G191B2B fluxes confirm the above estimates of uncertainty in STIS fluxes; but since GD153 provides the flux calibration, its residuals are unity, except for noise and small differences in the Balmer line cores. The small (<1%) systematic deviations from unity for the G230LB and G430L observations of G191B2B in the lower panels of Figures 4a-b may be caused by sensitivity changes over the approximately 5 months between the epochs of the GD153 baseline observations in SMOV and the G191B2B observations in 1997 October-November or else by different sensitivities at the different locations on the CCD. This difference in position is 5 6 px in the dispersion direction and 2-3 px in the perpendicular direction. The systematic deviations from unity for G750L have additions to the list of possible causes: Beyond 6220 Å, contemporaneous flats are used with a normalization to unity that may be in error by ~1%. (No flat field correction is done below 6220 Å, for G750L.) Beyond the Paschen jump at 8200 Å, the models that define the standard stars are uncertain by an additional 1 2%. Acknowledgments We thank Don Lindler and Phil Plait for essential data reduction advice. D. Finley and R. Saffer found the reference for the radial velocity of G191B2B. Thanks to S. Baum for careful review and suggested improvements to this ISR. References Bohlin, R. C. 1996, AJ, 111, Bohlin, R. C., Colina, L., & Finley, D. S. 1995, AJ, 110, Leitherer, C. & Bohlin, R., 1997, Instrument Science Report, STIS 97-13, (Baltimore: STScI). Reid, N., & Wegner, G., 1988, ApJ, 335,
9 Figures Figure 1: Sensitivity curve and residuals for optical element G140L, derived from 2 averaged observations of GD153. 9
10 Figure 2a: Sensitivity curve and residuals for optical element G230L 10
11 Figure 2b: Sensitivity curve and residuals for optical element G230LB 11
12 Figure 2c: Sensitivity curve and residuals for optical element G430L 12
13 Figure 2d: Sensitivity curve and residuals for optical element G750L at central wavelength 7751 Å 13
14 Figure 3: Line profile at Ly α of GD153, illustrating the good agreement of the model (solid line) and FOS (dashed line) in comparison to the STIS data (heavy jagged line) through a wide 2 slit. The excess scattered light will be much less for observations through narrow STIS slits. 14
15 Figure 4a-4c: Residuals of STIS fluxes for GD153 and G191B2B in comparison with the standard star model for G230LB (4a), G430L (4b), and G750L (4c). Since the flux calibration is based on GD153, its residuals are unity, except for noise and small differences in the Balmer line cores. Figure 4a Figure 4b 15
16 Figure 4c 16
17 17
SBC FLATS: PRISM P-FLATS and IMAGING L-FLATS
Instrument Science Report ACS 2006-08 SBC FLATS: PRISM P-FLATS and IMAGING L-FLATS R. C. Bohlin & J. Mack December 2006 ABSTRACT The internal deuterium lamp was used to illuminate the SBC detector through
More informationImproved Photometry for G750L
SPACE TELESCOPE SCIENCE INSTITUTE Operated for NASA by AURA Instrument Science Report STIS 2015-01(v1) Improved Photometry for G750L R.C. Bohlin 1, C.R. Proffitt 1 1 Space Telescope Science Institute,
More informationTECHNICAL REPORT. Doc #: Date: Rev: JWST-STScI , SM-12 August 31, Authors: Karl Gordon, Ralph Bohlin. Phone:
When there is a discrepancy between the information in this technical report and information in JDox, assume JDox is correct. TECHNICAL REPORT Title: Title: JWST Absolute Flux Calibration II: Expanded
More informationFLAT FIELDS FROM THE MOONLIT EARTH
Instrument Science Report WFPC2 2008-01 FLAT FIELDS FROM THE MOONLIT EARTH R. C. Bohlin, J. Mack, and J. Biretta 2008 February 4 ABSTRACT The Earth illuminated by light from the full Moon was observed
More informationAn Algorithm for Correcting CTE Loss in Spectrophotometry of Point Sources with the STIS CCD
An Algorithm for Correcting CTE Loss in Spectrophotometry of Point Sources with the STIS CCD Ralph Bohlin and Paul Goudfrooij August 8, 2003 ABSTRACT The correction for the change in sensitivity with time
More informationFringe Correction for STIS Near-IR Long-Slit Spectra using Contemporaneous Tungsten Flat Fields
1997 HST Calibration Workshop Space Telescope Science Institute, 1997 S. Casertano, et al., eds. Fringe Correction for STIS Near-IR Long-Slit Spectra using Contemporaneous Tungsten Flat Fields Paul Goudfrooij
More informationNew On-Orbit Sensitivity Calibration for All STIS Echelle Modes
New On-Orbit Sensitivity Calibration for All STIS Echelle Modes Alessandra Aloisi, Ralph Bohlin, and Jessica Kim Quijano January 18, 2007 ABSTRACT On-orbit sensitivities for the 32 medium- and high-resolution
More informationCalibration of ACS Prism Slitless Spectroscopy Modes
The 2005 HST Calibration Workshop Space Telescope Science Institute, 2005 A. M. Koekemoer, P. Goudfrooij, and L. L. Dressel, eds. Calibration of ACS Prism Slitless Spectroscopy Modes S. S. Larsen, M. Kümmel
More informationSMOV Absolute Flux Calibration of the COS FUV Modes
Instrument Science Report COS 2010-02(v1) SMOV Absolute Flux Calibration of the COS FUV Modes Derck Massa 1, Charles Keyes 1, Steve Penton 2, Ralph Bohlin 1, and Cynthia Froning 2 1 Space Telescope Science
More informationExtraction of Point Source Spectra from STIS Long Slit Data
1997 HST Calibration Workshop Space Telescope Science Institute, 1997 S. Casertano, et al., eds. Extraction of Point Source Spectra from STIS Long Slit Data J. R. Walsh Spect Telescope European Coordinating
More informationThe in-orbit wavelength calibration of the WFC G800L grism
The in-orbit wavelength calibration of the WFC G800L grism A. Pasquali, N. Pirzkal, J.R. Walsh March 5, 2003 ABSTRACT We present the G800L grism spectra of the Wolf-Rayet stars WR45 and WR96 acquired with
More informationVerification of COS/FUV Bright Object Aperture (BOA) Operations at Lifetime Position 3
Instrument Science Report COS 2015-05(v1) Verification of COS/FUV Bright Object Aperture (BOA) Operations at Lifetime Position 3 Andrew Fox 1, John Debes 1, & Julia Roman-Duval 1 1 Space Telescope Science
More informationACS CCDs UV and narrowband filters red leak check
Instrument Science Report ACS 2007-03 ACS CCDs UV and narrowband filters red leak check Marco Chiaberge and Marco Sirianni May 01, 2007 ABSTRACT We present results of the observations of the star 15 Mon,
More informationSBC L-Flat Corrections and Time-Dependent Sensitivity
SBC L-Flat Corrections and Time-Dependent Sensitivity J. Mack, R. Gilliland, R. van der Marel, and R. Bohlin November 17, 2005 ABSTRACT The uniformity of the SBC detector response has been assessed using
More informationImpacts of focus on aspects of STIS UV Spectroscopy
Instrument Science Report STIS 2018-06 Impacts of focus on aspects of STIS UV Spectroscopy Allyssa Riley 1, TalaWanda Monroe 1, & Sean Lockwood 1 1 Space Telescope Science Institute, Baltimore, MD November
More informationUpdated flux calibration and fringe modelling for the ACS/WFC G800L grism
Updated flux calibration and fringe modelling for the ACS/WFC G800L grism H. Kuntschner, M. Kümmel, J. R. Walsh January 25, 2008 ABSTRACT A revised flux calibration is presented for the G800L grism with
More informationThe HST Set of Absolute Standards for the 0.12 µm to 2.5 µm Spectral Range
Instrument Science Report CAL/SCS-010 The HST Set of Absolute Standards for the 0.12 µm to 2.5 µm Spectral Range L. Colina, R. Bohlin, D. Calzetti, C. Skinner, S. Casertano October 3, 1996 ABSTRACT A proposal
More informationGrism Sensitivities and Apparent Non-Linearity
Instrument Science Report NICMOS 2005-002 Grism Sensitivities and Apparent Non-Linearity Ralph C. Bohlin, Don J. Lindler, & Adam Riess May 10, 2005 ABSTRACT Recent grism observations using the NICMOS instrument
More informationWavelength Calibration Accuracy for the STIS CCD and MAMA Modes
SPACE TELESCOPE SCIENCE INSTITUTE Operated for NASA by AURA Instrument Science Report STIS 11-1(v1) Wavelength Calibration Accuracy for the STIS CCD and MAMA Modes Ilaria Pascucci 1, Phil Hodge 1, Charles
More informationStudy of the evolution of the ACS/WFC sensitivity loss
Instrument Science Report ACS 2013 01 Study of the evolution of the ACS/WFC sensitivity loss Leonardo Úbeda and Jay Anderson Space Telescope Science Institute January 28, 2013 ABSTRACT We present a study
More informationDelivery of a new ACS SBC throughput curve for Synphot
Delivery of a new ACS SBC throughput curve for Synphot Francesca R. Boffi, M. Sirianni, R. A. Lucas, N. R. Walborn, C. R. Proffitt April 18, 2008 ABSTRACT On November 12th, 2007 a new ACS SBC throughput
More informationarxiv:astro-ph/ v3 7 Apr 2005 Space Telescope Science Institute 2, 3700 San Martin Drive, Baltimore, MD 21218, U.S.A.
Accepted at Publications of the Astronomical Society of the Pacific (June 2005 issue) A cross-calibration between Tycho-2 photometry and HST spectrophotometry arxiv:astro-ph/0504085v3 7 Apr 2005 J. Maíz
More informationA Recalibration of Optical Photometry Based on STIS Spectrophotometry
The 2005 HST Calibration Workshop Space Telescope Science Institute, 2005 A. M. Koekemoer, P. Goudfrooij, and L. L. Dressel, eds. A Recalibration of Optical Photometry Based on STIS Spectrophotometry J.
More informationFlat Fields and Flux Calibrations for the COS FUV Channel at Lifetime Position 4
Instrument Science Report COS 2018-20(v1) Flat Fields and Flux Calibrations for the COS FUV Channel at Lifetime Position 4 William J. Fischer 1, Marc Rafelski 1, and Gisella de Rosa 1 1 Space Telescope
More informationObserver Anomaly(?): Recent Jitter and PSF Variations
Instrument Science Report TEL 2005-01 Observer Anomaly(?): Recent Jitter and PSF Variations R. L. Gilliland gillil@stsci.edu February 2005 Abstract An anomaly in the HST Pointing Control System (PCS) has
More informationA Cross-Calibration between Tycho-2 Photometry and Hubble Space Telescope Spectrophotometry
Publications of the Astronomical Society of the Pacific, 117:615 619, 2005 June 2005. he Astronomical Society of the Pacific. All rights reserved. Printed in U.S.A. A Cross-Calibration between ycho-2 Photometry
More informationDark Rate of the STIS NUV Detector
SPACE TELESCOPE SCIENCE INSTITUTE Operated for NASA by AURA Instrument Science Report STIS 2011-03 Dark Rate of the STIS NUV Detector Wei Zheng 1, Charles Proffitt 2, and David Sahnow 1 1 Department of
More informationNICMOS Photometric Calibration
2002 HST Calibration Workshop Space Telescope Science Institute, 2002 S. Arribas, A. Koekemoer, and B. Whitmore, eds. NICMOS Photometric Calibration Mark Dickinson, Megan Sosey Space Telescope Science
More informationCOS FUV Focus Determination for the G140L Grating
Instrument Science Report COS 2012-01 COS FUV Focus Determination for the G140L Grating Parviz Ghavamian 1 Space Telescope Science Institute, Baltimore, MD October 03, 2012 ABSTRACT The procedures for
More informationEarth Flats. 1. Introduction. Instrument Science Report ACS R. C. Bohlin, J. Mack, G. Hartig, & M. Sirianni October 25, 2005
Instrument Science Report ACS 2005-12 Earth Flats R. C. Bohlin, J. Mack, G. Hartig, & M. Sirianni October 25, 2005 ABSTRACT Since the last ISR 2003-02 on the use of Earth observations for a source of flat
More informationNICMOS Status and Plans
1997 HST Calibration Workshop Space Telescope Science Institute, 1997 S. Casertano, et al., eds. NICMOS Status and Plans Rodger I. Thompson Steward Observatory, University of Arizona, Tucson, AZ 85721
More informationThe Effective Spectral Resolution of the WFC and HRC Grism
The Effective Spectral Resolution of the WFC and HRC Grism A. Pasquali, N. Pirzkal, J.R. Walsh, R.N. Hook, W. Freudling, R. Albrecht, R.A.E. Fosbury March 7, 2001 ABSTRACT We present SLIM simulations of
More informationPredicted Countrates for the UV WFC3 Calibration Subsystem using Deuterium Lamps
Predicted Countrates for the UV WFC3 Calibration Subsystem using Deuterium Lamps S.Baggett, J. Sullivan, and M. Quijada May 17,24 ABSTRACT Predicted WFC3 calibration subsystem countrates have been computed
More informationXMM-Newton Optical-UV Monitor: introduction and calibration status OM instrument and calibration
XMM-Newton Optical-UV Monitor: introduction and calibration status OM instrument and calibration Antonio Talavera XMM-Newton Science Operation Centre, ESAC, ESA OM: Instrument Description 30 cm Ritchey-Chretien
More informationWFC3/UVIS Photometric Transformations
Instrument Science Report WFC3 2014-016 WFC3/UVIS Photometric Transformations Kailash Sahu, Susana Deustua and Elena Sabbi January 05, 2017 ABSTRACT We provide photometric transformation coefficients for
More informationMeasurement of the stellar irradiance
Measurement of the stellar irradiance Definitions Specific Intensity : (monochromatic) per unit area normal to the direction of radiation per unit solid angle per unit wavelength unit (or frequency) per
More informationThe HST/STIS Next Generation Spectral Library
The 2005 HST Calibration Workshop Space Telescope Science Institute, 2005 A. M. Koekemoer, P. Goudfrooij, and L. L. Dressel, eds. The HST/STIS Next Generation Spectral Library M. D. Gregg 1 Department
More informationPACS Spectroscopy performance and calibration PACS Spectroscopy performance and calibration
1 of 18 PACS Spectroscopy performance and Prepared by Bart Vandenbussche With inputs by Alessandra Contursi Helmut Feuchtgruber Katrina Exter Christophe Jean Albrecht Poglitsch Elena Puga Pierre Royer
More informationCOS FUV Dispersion Solution Verification at the New Lifetime Position
SPACE TELESCOPE SCIENCE INSTITUTE Operated for NASA by AURA Instrument Science Report COS 2013-06(v1) COS FUV Dispersion Solution Verification at the New Lifetime Position Paule Sonnentrucker 1, Julia
More informationThe Accuracy of WFPC2 Photometric Zeropoints
The Accuracy of WFPC2 Photometric Zeropoints Inge Heyer, Marin Richardson, Brad Whitmore, Lori Lubin July 23, 2004 ABSTRACT The accuracy of WFPC2 photometric zeropoints is examined using two methods. The
More informationUpdates to the COS/NUV Dispersion Solution Zero-points
Instrument Science Report COS 017-0 Updates to the COS/NUV Dispersion Solution Zero-points Rachel Plesha 1, Paule Sonnentrucker 1,, Cristina Oliveira 1, Julia Roman-Duval 1 1 Space Telescope Science Institute,
More informationEXPOSURE TIME ESTIMATION
ASTR 511/O Connell Lec 12 1 EXPOSURE TIME ESTIMATION An essential part of planning any observation is to estimate the total exposure time needed to satisfy your scientific goal. General considerations
More informationACS after SM4: RELATIVE GAIN VALUES AMONG THE FOUR WFC AMPLIFIERS
Instrument Science Report ACS 2009-03 ACS after SM4: RELATIVE GAIN VALUES AMONG THE FOUR WFC AMPLIFIERS R. C. Bohlin, A. Maybhate, & J. Mack 2009 October 8 ABSTRACT For the default setting of gain=2, the
More informationCalibration Goals and Plans
CHAPTER 13 Calibration Goals and Plans In This Chapter... Expected Calibration Accuracies / 195 Calibration Plans / 197 This chapter describes the expected accuracies which should be reached in the calibration
More informationHigh Signal-to-Noise, Differential NICMOS Spectrophotometry
Instrument Science Report NICMOS 2003-001 High Signal-to-Noise, Differential NICMOS Spectrophotometry R.L. Gilliland, S. Arribas January 7, 2003 ABSTRACT We report analysis for NICMOS CAL/9642, High S/N
More informationReduction procedure of long-slit optical spectra. Astrophysical observatory of Asiago
Reduction procedure of long-slit optical spectra Astrophysical observatory of Asiago Spectrograph: slit + dispersion grating + detector (CCD) It produces two-dimension data: Spatial direction (x) along
More informationLab 4 Radial Velocity Determination of Membership in Open Clusters
Lab 4 Radial Velocity Determination of Membership in Open Clusters Sean Lockwood 1, Dipesh Bhattarai 2, Neil Lender 3 December 2, 2007 Abstract We used the Doppler velocity of 29 stars in the open clusters
More informationPoint-Source CCD Photometry with STIS: Correcting for CTE loss
SPACE TELESCOPE SCIENCE INSTITUTE Operated for NASA by AURA Point-Source CCD Photometry with STIS: Correcting for CTE loss Space Telescope Science Institute Methods to measure CTE of STIS CCD (Visual)
More informationFlux Units and Line Lists
APPENDIX 2 Flux Units and Line Lists In This Appendix... Infrared Flux Units / 255 Formulae / 258 Look-up Tables / 259 Examples / 266 Infrared Line Lists / 266 In this chapter we provide a variety of background
More information5.6 Spectrophotometry and Magnitudes
5.6. SPECTROPHOTOMETRY AND MAGNITUDES 87 a constant optical depth, τ = χ L, across the beam cross section (so that the absorption is independent of the point of origin of a beam element emitted from the
More informationCommissioning of the Hanle Autoguider
Commissioning of the Hanle Autoguider Copenhagen University Observatory Edited November 10, 2005 Figure 1: First light image for the Hanle autoguider, obtained on September 17, 2005. A 5 second exposure
More informationXMM. XMM-Newton Optical and UV Monitor (OM) Calibration Status. XMM-SOC-CAL-TN-0019 Issue 6.0
XMM XMM-Newton Optical and UV Monitor (OM) Calibration Status XMM-SOC-CAL-TN-0019 Issue 6.0 Antonio Talavera, OMCal Team XMM-Newton Science Operations Center OMCal Team MSSL-UCL 20 January 2011 Revision
More informationInternal Flat Field Monitoring II. Stability of the Lamps, Flat Fields, and Gain Ratios
Instrument Science Report WFPC2 99-01 Internal Flat Field Monitoring II. Stability of the Lamps, Flat Fields, and Gain Ratios C. O Dea, M. Mutchler, and M. Wiggs April 27, 1999 ABSTRACT We have compared
More informationCosmic Origins Spectrograph Instrument Mini-Handbook for Cycle 12
Version 1.0 October, 2002 Cosmic Origins Spectrograph Instrument Mini-Handbook for Cycle 12 Available in Cycle 13 Do not propose for COS in Cycle 12 Space Telescope Science Institute 3700 San Martin Drive
More informationBreathing, Position Drift, and PSF Variations on the UVIS Detector
SPACE TELESCOPE SCIENCE INSTITUTE Operated for NASA by AURA Instrument Science Report WFC3 1-1 Breathing, Position Drift, and PSF Variations on the UVIS Detector L. Dressel July 13, 1 ABSTRACT This study
More informationCharacterizing the COS OSM1 Drift in the Dispersion Direction
Instrument Science Report COS 2016-02(v1) Characterizing the COS OSM1 Drift in the Dispersion Direction James White 1, Gisella de Rosa 1, Rachel Plesha 1, David Sahnow 1 1 Space Telescope Science Institute,
More informationCOS Cycle 17: 20 programs 149 external orbits 446 internals FUV Detector Sensitivity Monitor 36 0 Oct. 3, 2010
Prop. ID Title External Internal Status/End obs Cycle 17 11891 NUV MAMA Fold Distribution 0 2 last visit on hold 11894 NUV Detector Dark Monitor 0 114 Oct. 31, 2010 11896 NUV Spectroscopic Sensitivity
More informationWFC3/IR Persistence as Measured in Cycle 17 using Tungsten Lamp Exposures
WFC3/IR Persistence as Measured in Cycle 17 using Tungsten Lamp Exposures Knox S. Long, Sylvia Baggett, Susana Deustua & Adam Riess November 17, 2010 ABSTRACT Like most IR arrays, the IR detector incorporated
More informationNICMOS Cycles 13 and 14 Calibration Plans
Instrument Science Report NICMOS 2005-005 NICMOS Cycles 13 and 14 Calibration s Santiago Arribas, Eddie Bergeron, Roelof de Jong, Sangeeta Malhotra, Bahram Mobasher, Keith Noll, Al Schultz, Tommy Wiklind,
More informationPACS Spectroscopy performance and calibration PACS Spectroscopy performance and calibration
1 of 18 PACS Spectroscopy performance and PICC-KL-TN-041 Prepared by With inputs by Bart Vandenbussche Joris Blommaert Alessandra Contursi Helmut Feuchtgruber Christophe Jean Albrecht Poglitsch Pierre
More informationCOS/FUV Spatial and Spectral Resolution at the new Lifetime Position
SPACE TELESCOPE SCIENCE INSTITUTE Operated for NASA by AURA Instrument Science Report COS 2013-07 COS/FUV Spatial and Spectral Resolution at the new Lifetime Position Julia Roman-Duval 1, Erin Elliott
More informationNICMOS Focus Field Variations (FFV) and Focus Centering
Instrument Science Report NICMOS-98-005 NICMOS Focus Field Variations (FFV) and Focus Centering A.Suchkov & G.Galas March 16, 1998 ABSTRACT NICMOS foci are known to vary across detector s field of view.
More informationAccuracy of VIMOS night-time and daytime wavelength calibrations
Accuracy of VIMOS night-time and daytime wavelength calibrations Burkhard Wolff, Steffen Mieske, Juan Carlos Muñoz-Mateos, Sabine Möhler, Michael Hilker 10 December 2014 Abstract Night-time calibrations
More informationAddendum: GLIMPSE Validation Report
August 18, 2004 Addendum: GLIMPSE Validation Report The GLIMPSE Team 1. Motivation In our Validation Report of Jan. 30, 2004, we produced reliability calculations and discussed photometric accuracy estimates
More informationScattered Light from the Earth Limb Measured with the STIS CCD
Instrument Science Report STIS 98 21 Scattered Light from the Earth Limb Measured with the STIS CCD Dick Shaw, Merle Reinhart, and Jennifer Wilson 17 June 1998 ABSTRACT We describe a recent program to
More informationOn the calibration of WFCAM data from 2MASS
On the calibration of WFCAM data from 2MASS Authors: Simon Hodgkin, Mike Irwin Draft: September 28 th 2006 Modifications: ID: VDF-TRE-IOA-00011-0000* 1 Introduction The requirement on VDFS is to photometrically
More informationThe TV3 ground calibrations of the WFC3 NIR grisms
The TV3 ground calibrations of the WFC3 NIR grisms H. Kuntschner, H. Bushouse, J. R. Walsh, M. Kümmel July 10, 2008 ABSTRACT Based on thermal vacuum tests (TV3; March/April 2008), the performance of the
More informationCHEMICAL ABUNDANCE ANALYSIS OF RC CANDIDATE STAR HD (46 LMi) : PRELIMINARY RESULTS
Dig Sites of Stellar Archeology: Giant Stars in the Milky Way Ege Uni. J. of Faculty of Sci., Special Issue, 2014, 145-150 CHEMICAL ABUNDANCE ANALYSIS OF RC CANDIDATE STAR HD 94264 (46 LMi) : PRELIMINARY
More informationLab 4: Stellar Spectroscopy
Name:... Astronomy 101: Observational Astronomy Fall 2006 Lab 4: Stellar Spectroscopy 1 Observations 1.1 Objectives and Observation Schedule During this lab each group will target a few bright stars of
More informationA Python Script for Aligning the STIS Echelle Blaze Function
Instrument Science Report STIS 2018-01 A Python Script for Aligning the STIS Echelle Blaze Function Malinda Baer 1, 2, Charles R. Proffitt 2, & Sean A. Lockwood 2 1 Ohio State University, Columbus, OH
More informationWFPC2 Cycle 7 Calibration Plan
Instrument Science Report WFPC2-97-06 WFPC2 Cycle 7 Calibration Plan S. Casertano and the WFPC2 group August 18, 1997 ABSTRACT This report describes in detail the WFPC2 observations planned to maintain
More informationUVIT IN ORBIT CALIBRATIONS AND CALIBRATION TOOLS. Annapurni Subramaniam IIA (On behalf of the UVIT team)
UVIT IN ORBIT CALIBRATIONS AND CALIBRATION TOOLS Annapurni Subramaniam IIA (On behalf of the UVIT team) Calibrations: : Calibrations are of two types: 1. Ground calibrations 2. In orbit calibrations In
More informationFirst On-orbit Measurements of the WFC3-IR Count-rate Non-Linearity
First On-orbit Measurements of the WFC3-IR Count-rate Non-Linearity A. G. Riess March 10, 2010 ABSTRACT Previous HgCdTe detectors on HST have suffered from a count-rate dependent non-linearity, motivating
More information11041,11042,11043: ACS CCD Daily Monitor
11041,11042,11043: ACS CCD Daily Monitor Purpose. This program consists of a series of basic tests to measure the readnoise and dark current of the ACS CCDs and to track the growth of hot pixels. The images
More informationAstrometric Performance of STIS CCD CTI Corrections on Omega Cen Images
Instrument Science Report STIS 2015-05 Astrometric Performance of STIS CCD CTI Corrections on Omega Cen Images John Biretta, Sean Lockwood, and John Debes September 28, 2015 ABSTRACT We are in the process
More informationWFC3 IR Blobs, IR Sky Flats and the measured IR background levels
The 2010 STScI Calibration Workshop Space Telescope Science Institute, 2010 Susana Deustua and Cristina Oliveira, eds. WFC3 IR Blobs, IR Sky Flats and the measured IR background levels N. Pirzkal 1 Space
More informationData Processing in DES
Data Processing in DES Brian Yanny Oct 28, 2016 http://data.darkenergysurvey.org/fnalmisc/talk/detrend.p Basic Signal-to-Noise calculation in astronomy: Assuming a perfect atmosphere (fixed PSF of p arcsec
More informationThe STIS CCD Spectroscopic Line Spread Functions 1
2002 HST Calibration Workshop Space Telescope Science Institute, 2002 S. Arribas, A. Koekemoer, and B. Whitmore, eds. The STIS CCD Spectroscopic Line Spread Functions 1 T. Gull, D. Lindler, 2 D. Tennant,
More informationGDR1 photometry. CU5/DPCI team
GDR1 photometry CU5/DPCI team What is, or isn't included GDR1 only provides G mean flux and error Derived mean magnitude, all entries Zero point used is in Vega system Zero point for AB system also available
More informationAstro 500 A500/L-15 1
Astro 500 A500/L-15 1 Lecture Outline Spectroscopy from a 3D Perspective ü Basics of spectroscopy and spectrographs ü Fundamental challenges of sampling the data cube Approaches and example of available
More informationKepler photometric accuracy with degraded attitude control
Kepler photometric accuracy with degraded attitude control Hans Kjeldsen, Torben Arentoft and Jørgen Christensen-Dalsgaard KASOC, Stellar Astrophysics Centre, Aarhus University, Denmark - 25 July 2013
More informationWFPC2 Dark Current vs. Time
WFPC2 Dark Current vs. Time J. Mack, J. Biretta, S. Baggett, C. Proffitt June 7, 2001 ABSTRACT On-going measurements of the dark current in the WFPC2 detectors indicate that the average level of dark current
More informationImproving the Relative Accuracy of the HETGS Effective Area
October 14, 2005 Improving the Relative Accuracy of the HETGS Effective Area Herman L. Marshall (MIT Kavli Institute) hermanm@space.mit.edu ABSTRACT I present updates to the HETGS grating efficiencies.
More informationThe shapes of faint galaxies: A window unto mass in the universe
Lecture 15 The shapes of faint galaxies: A window unto mass in the universe Intensity weighted second moments Optimal filtering Weak gravitational lensing Shear components Shear detection Inverse problem:
More informationWFC3 Cycle 18 Calibration Program
Instrument Science Report WFC3 2011-14 WFC3 Cycle 18 Calibration Program S. Deustua June 30 2011 The WFC3 Cycle 18 Calibration Program runs from October 2010 through September 2011, and will measure and
More informationSOLSTICE I and II: Ultraviolet Variability. Marty Snow, Bill McClintock, Tom Woods, and Gary Rottman Laboratory for Atmospheric and Space Physics
SOLSTICE I and II: Ultraviolet Variability Marty Snow, Bill McClintock, Tom Woods, and Gary Rottman Laboratory for Atmospheric and Space Physics Outline SOLSTICE I and II Measurement Equations Individual
More informationHere Be Dragons: Characterization of ACS/WFC Scattered Light Anomalies
Instrument Science Report ACS 2016-06 Here Be Dragons: Characterization of ACS/WFC Scattered Light Anomalies Blair Porterfield, Dan Coe, Shireen Gonzaga, Jay Anderson, Norman Grogin November 1, 2016 Abstract
More informationPerformance of the NICMOS ETC Against Archived Data
Performance of the NICMOS ETC Against Archived Data M. Sosey June 19, 2001 ABSTRACT A robust test of the newest version of the NICMOS Exposure Time Calculator (ETC) was conducted in order to assess its
More informationXMM-Newton Calibration
XMM-Newton Calibration Michael Smith, on behalf of XMM-SOC and Instrument Teams 18 th XMM-Newton Users Group Meeting, ESAC, 11 May 2017 ESA UNCLASSIFIED - For Official Use Outline 1. Status of calibration
More informationFGS2r: Deadtime, Background, Photon Aging, Sensitivity Calibrations, and Noise Properties
Instrument Science Report TEL 2009-01 FGS2r: Deadtime, Background, Photon Aging, Sensitivity Calibrations, and Noise Properties R. L. Gilliland, R. C. Bohlin, P. R. McCullough, & E. Nelan gillil@stsci.edu
More informationarxiv:astro-ph/ v1 2 Oct 2002
**TITLE** ASP Conference Series, Vol. **VOLUME***, **YEAR OF PUBLICATION** **NAMES OF EDITORS** The Extra-Solar Planet Imager (ESPI) arxiv:astro-ph/0210046v1 2 Oct 2002 P. Nisenson, G.J. Melnick, J. Geary,
More informationPhotometric systems for GAIA s Broad Band Photometer
Photometric systems for GAIA s Broad Band Photometer L. Lindegren GAIA LL 45 (V.1 22 April 23) Abstract. Two photometric systems for the GAIA broad-band photometer (BBP) are proposed, assuming that silver
More informationObserving with the Infrared Spectrograph
Observing with the Infrared Spectrograph C. Grillmair, L. Armus GO Workshop 21-22 November 2002 Outline 1) Meet the IRS IST 2) Basic IRS capabilities 3) Observing and readout modes 4) Data products and
More informationThe Gaia Mission. Coryn Bailer-Jones Max Planck Institute for Astronomy Heidelberg, Germany. ISYA 2016, Tehran
The Gaia Mission Coryn Bailer-Jones Max Planck Institute for Astronomy Heidelberg, Germany ISYA 2016, Tehran What Gaia should ultimately achieve high accuracy positions, parallaxes, proper motions e.g.
More informationOptimal resolutions for optical and NIR spectroscopy S. Villanueva Jr.* a, D.L. DePoy a, J. L. Marshall a
Optimal resolutions for optical and NIR spectroscopy S. Villanueva Jr.* a, D.L. DePoy a, J. L. Marshall a a Department of Physics and Astronomy, Texas A&M University, 4242 TAMU, College Station, TX, USA
More informationSKINAKAS OBSERVATORY. Astronomy Projects for University Students PROJECT SUPERNOVA REMNANTS
PROJECT 10 SUPERNOVA REMNANTS Objective: The purpose of this exercise is also twofold. The first one is to gain further experience with the analysis of narrow band images (as in the case of planetary nebulae)
More informationAnalysis of wavelength shifts reported for X-shooter spectra
Analysis of wavelength shifts reported for X-shooter spectra S. Moehler (SDP) June 15, 2015 Executive Summary I investigated the causes for wavelength offsets seen in telluric lines and sky lines of extracted
More informationExploring Data. Keck LRIS spectra. Handbook of CCD Astronomy by Steve Howell Chap. 4, parts of 6
Exploring Data Keck LRIS spectra Handbook of CCD Astronomy by Steve Howell Chap. 4, parts of 6 FITS: Flexible Image Transport System Digital file format used to store astronomical images, data, and catalogs.
More informationSPACE TELESCOPE SCIENCE INSTITUTE. ACS Polarization Calibration: Introduction and Progress Report
1 ACS Polarization Calibration: Introduction and Progress Report J. Biretta, V. Platais, F. Boffi, W. Sparks, J. Walsh Introduction: Theory / ACS Polarizers / Supported Modes Potential Issues for ACS Polarization
More informationCover Page. The handle holds various files of this Leiden University dissertation
Cover Page The handle http://hdl.handle.net/1887/49240 holds various files of this Leiden University dissertation Author: Schwarz, Henriette Title: Spinning worlds Issue Date: 2017-06-01 89 4 Spin measurement
More information