scholarly journals Spectroscopy of southern δ Scuti stars

2004 ◽  
Vol 193 ◽  
pp. 275-278
Author(s):  
Malcolm Cropp ◽  
Karen R. Pollard ◽  
Jovan Skuljan
Keyword(s):  
New Zealand ◽  
Spectral Line ◽  
Radial Velocity ◽  
Spectroscopic Data ◽  
Cross Correlation ◽  
Correlation Technique ◽  
Echelle Spectrograph ◽  
Cross Correlation Technique ◽  
Scuti Stars ◽  
Δ Scuti Stars

AbstractFour δ Scuti stars were observed with the HERCULES fibrefed échelle spectrograph at Mount John University Observatory, New Zealand. These observations were analysed by looking at the radial velocity variations as given by a cross-correlation technique as well as spectral line moment variations. These results were compared to published photometric studies of these stars to see if the modes identified in the photometry were also present in the spectroscopic data obtained.

scholarly journals Absolute Radial Velocities by Cross-Correlation with Synthetic Spectra

1999 ◽  
Vol 170 ◽  
pp. 91-97 ◽  
Author(s):  
J. Skuljan ◽  
J. B. Hearnshaw ◽  
P. L. Cottrell
Keyword(s):  
Cross Correlation ◽  
Zero Point ◽  
Radial Velocities ◽  
Correlation Technique ◽  
Late Type ◽  
Echelle Spectrograph ◽  
Stellar Spectra ◽  
Synthetic Spectra ◽  
Cross Correlation Technique ◽  
The Continuum

AbstractPrecise absolute radial velocities have been measured for several hundred late-type stars at Mt John University Observatory with the 1-m telescope, fiber-fed échelle spectrograph, and Thomson CCD. Six échelle orders in the green (5000−5600 Å) are used. Many delicate steps have been undertaken in order to maintain exactly the same conditions, both in recording and reducing the spectra, over a period of 18 months. A cross-correlation technique with theoretical spectra computed by R. L. Kurucz has been chosen to determine the absolute radial velocities. Blue sky spectra have been used to monitor systematic zero-point fluctuations from one observing run to another. An additional correlation between the measured velocities and average number of A/D units in the continuum has been discovered and used for fine adjustments, significantly improving the results. A random uncertainty of 10–20 ms−1 has been achieved for stellar spectra having intrinsically constant radial velocities.

Turbulence Variations in Cepheids

1995 ◽  
Vol 155 ◽  
pp. 371-372
Author(s):  
David Bersier ◽  
Gilbert Burki
Keyword(s):  
Radial Velocity ◽  
Cross Correlation ◽  
Gaussian Approximation ◽  
Forthcoming Paper ◽  
Mean Value ◽  
Correlation Technique ◽  
Doppler Width ◽  
Pulsational Velocity ◽  
The Mean ◽  
Cross Correlation Technique

From radial velocity measurements obtained with a cross-correlation technique, the variation of turbulence during the pulsation cycle is studied for a sample of 40 Cepheids. We will propose a new way to separate classical and s-Cepheids. More complete results will appear in a forthcoming paper (Bersier & Burki 1995)The radial velocities have been measured with the spectrometer CORAVEL (Baranne et al. 1979), whose cross-correlation function (CCF) is fitted with a Gaussian, giving the radial velocity Vr, the width σobs the depth H and the continuum, normalised to 1. The pulsation broadens the lines and thus also the CCF. In the Gaussian approximation one can writewhere σobs is the observed width, σinst is the instrumental width, σpuls is the additional width caused by the pulsational velocity field and σres contains all the other effects (turbulence, rotation, magnetic field, etc.). To be less affected by the noise in the data, a Fourier series has been fitted to each curve of σobs. With numerical simulations, one is able to synthesise the additional Doppler width due to pulsation, with a high accuracy. The instrumental width being well known for CORAVEL, the computation of σres is then straightforward. One then has a curve in phase for σres. From this curve, we determined the maximum residual broadening σmax (observed at or very close to minimum radius), and the width σo that the star would have if it did not pulsate. As shown by Bersier & Burki (1995), σo is slightly higher than the mean value of σres.

scholarly journals The emergence of the red sequence at z~2 seen through galaxy clustering in the UKIDSS UDS

2012 ◽  
Vol 8 (S295) ◽  
pp. 105-108
Author(s):  
William G. Hartley ◽  
Omar Almaini ◽  
Alice Mortlock ◽  
Chris Conselice ◽  
Keyword(s):  
Dark Matter ◽  
Cross Correlation ◽  
Near Infrared ◽  
Correlation Technique ◽  
Dark Matter Halos ◽  
Star Forming ◽  
Deep Survey ◽  
Cross Correlation Technique ◽  
Infrared Survey

AbstractWe use the UKIDSS Ultra-Deep Survey, the deepest degree-scale near-infrared survey to date, to investigate the clustering of star-forming and passive galaxies to z ~ 3.5. Our new measurements include the first determination of the clustering for passive galaxies at z > 2, which we achieve using a cross-correlation technique. We find that passive galaxies are the most strongly clustered, typically hosted by massive dark matter halos with Mhalo > 1013 M⊙ irrespective of redshift or stellar mass. Our findings are consistent with models in which a critical halo mass determines the transition from star-forming to passive galaxies.

Raman Chemical Imaging of Explosive-Contaminated Fingerprints

2009 ◽  
Vol 63 (11) ◽  
pp. 1197-1203 ◽  
Author(s):  
E. D. Emmons ◽  
A. Tripathi ◽  
J. A. Guicheteau ◽  
S. D. Christesen ◽  
A. W. Fountain
Keyword(s):  
Cross Correlation ◽  
Chemical Imaging ◽  
Correlation Technique ◽  
Bright Field ◽  
Characteristic Region ◽  
Biometric Analysis ◽  
Imaging Results ◽  
Raman Chemical Imaging ◽  
Cross Correlation Technique ◽  
Field Imaging

Raman chemical imaging (RCI) has been used to detect and identify explosives in contaminated fingerprints. Bright-field imaging is used to identify regions of interest within a fingerprint, which can then be examined to determine their chemical composition using RCI and fluorescence imaging. Results are presented where explosives in contaminated fingerprints are identified and their spatial distributions are obtained. Identification of explosives is obtained using Pearson's cosine cross-correlation technique using the characteristic region (500–1850 cm−1) of the spectrum. This study shows the ability to identify explosives nondestructively so that the fingerprint remains intact for further biometric analysis. Prospects for forensic examination of contaminated fingerprints are discussed.

Optoelectronic sensor applied to airflow velocity measurements through cross-correlation technique

2021 ◽  
Author(s):  
Alexandre Allil ◽  
Fábio Dutra ◽  
Cesar Cosenza Carvalho ◽  
Alex Dante ◽  
Regina Allil ◽  
...  
Keyword(s):  
Cross Correlation ◽  
Correlation Technique ◽  
Velocity Measurements ◽  
Airflow Velocity ◽  
Optoelectronic Sensor ◽  
Cross Correlation Technique

scholarly journals Precise Radial Velocity Measurements with a Cassegrain Spectrograph, I: Wavelength calibration

1999 ◽  
Vol 170 ◽  
pp. 63-67
Author(s):  
I. V. Ilyin ◽  
R. Duemmler
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Cross Correlation ◽  
Time Dependent ◽  
Instrumental Effects ◽  
Velocity Measurements ◽  
Echelle Spectrograph ◽  
Optical Telescope ◽  
La Palma ◽  
Observational Strategy

AbstractWe briefly describe the instrumental effects which affect the accuracy of the radial velocity measurements. We have implemented several methods to correct for the instability effects and improve the accuracy of the measurements. These include modifications of the observational strategy and a time-dependent wavelength solution as well as a discussion of the error of the offset from cross-correlation. These methods are applied to observations obtained with the high resolution échelle spectrograph SOFIN mounted at the Cassegrain focus of the alt-azimuth 2.56-m Nordic Optical Telescope, La Palma, Canary Islands.

scholarly journals SuperCLASS – I. The super cluster assisted shear survey: Project overview and data release 1

2020 ◽  
Vol 495 (2) ◽  
pp. 1706-1723 ◽  
Author(s):  
Richard A Battye ◽  
Michael L Brown ◽  
Caitlin M Casey ◽  
Ian Harrison ◽  
Neal J Jackson ◽  
...  
Keyword(s):  
Cross Correlation ◽  
Near Infrared ◽  
Correlation Technique ◽  
Large Array ◽  
Photometric Redshifts ◽  
Very Large Array ◽  
Infrared Observations ◽  
Data Release ◽  
L Band ◽  
Cross Correlation Technique

ABSTRACT The SuperCLuster Assisted Shear Survey (SuperCLASS) is a legacy programme using the e-MERLIN interferometric array. The aim is to observe the sky at L-band (1.4 GHz) to a r.m.s. of $7\, \mu {\rm Jy}\,$beam−1 over an area of $\sim 1\, {\rm deg}^2$ centred on the Abell 981 supercluster. The main scientific objectives of the project are: (i) to detect the effects of weak lensing in the radio in preparation for similar measurements with the Square Kilometre Array (SKA); (ii) an extinction free census of star formation and AGN activity out to z ∼ 1. In this paper we give an overview of the project including the science goals and multiwavelength coverage before presenting the first data release. We have analysed around 400 h of e-MERLIN data allowing us to create a Data Release 1 (DR1) mosaic of $\sim 0.26\, {\rm deg}^2$ to the full depth. These observations have been supplemented with complementary radio observations from the Karl G. Jansky Very Large Array (VLA) and optical/near infrared observations taken with the Subaru, Canada-France-Hawaii, and Spitzer Telescopes. The main data product is a catalogue of 887 sources detected by the VLA, of which 395 are detected by e-MERLIN and 197 of these are resolved. We have investigated the size, flux, and spectral index properties of these sources finding them compatible with previous studies. Preliminary photometric redshifts, and an assessment of galaxy shapes measured in the radio data, combined with a radio-optical cross-correlation technique probing cosmic shear in a supercluster environment, are presented in companion papers.

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