... The absolute flux calibration of NICMOS will be calculated from observations of standard stars with known flux distributions F( ). ... In order to expand the set of IR standard stars in the appropriate flux range for NICMOS, M. Rieke, R. Thompson, and collaborators at the University of Arizona are making photometric observations of solar-analog stars, which will be used to normalize the solar spectrum to the observed IR magnitudes. ... Relative flux references accurate to 1.5% for standard...

Next: HKPARMINT Up: Generation from In-Orbit Data Previous: Wavelength calibration Contents . Spectroscopic Standard stars, mainly white dwarfs, were observed with both OM grisms. The ISF is obtained by dividing the extracted spectrum, in count rate versus wavelength, by the standard flux of the star obtained from HST Calspec database. The results obtained from several stars are then averaged and the standard deviation is taken as the error in the ISF. ...

... An overall criterion for standard-star selection is the accuracy needed in the final results: if you need more accuracy, you will need more standard stars. ... While it is possible to get a rough estimate of the extinction by observing different standard stars at high and low airmasses, the relatively large conformity errors in most photometric systems, together with the low accuracy of some standards, make this method very inefficient (see Young [ 10 ], p.178). ...

... Stellar Evolution is driven entirely by the never ending battle between Pressure and Gravity . As imbalances are reached, the star is driven to find a new Energy source. ... Pressure and gravitational forces are equal, the star is stable and its core is sufficiently hot to fuse Hydrogen into Helium More about main sequence stars . ... The luminosity generated by the core fusion of Helium into Carbon is far greater than the shell luminosity associated with the fusion of Hydrogen into Helium. ...

... The first step to improve the FORS calibration is therefore to obtain data to allow a computation of the illumination correction across the field. ... Another limitation on the calibration accuracy has been the brightness of the Landolt standards which have forced the use of extremely short exposures introducing small but non-negligible shutter-time errors and also resulting in a very small number of useful standards per frame. ...

... ATNF Home . About ATNF . ... About ATNF overview . ... Australia Telescope Steering Committee . ... Parkes radio telescope . ... Visiting Parkes radio telescope . ... Parkes radio telescope webcam . ... We discuss variations of the atmospheric extinction coefficients and transformation equations to the standard UBVRI system based on observations of standard stars during 1996-1997 at Siding Spring Observatory using a thinned SITe CCD and coloured glass filters. ... Standard System Transformations . ...

Next: Definition of Scientific Misconduct Up: scientific Previous: Introduction . ... This Code of Good Practice closely follows the Statement on Safeguarding Good Scientific Practice issued by the Biotechnology and Biological Sciences Research Council (BBSRC) in 1998. ... The Observatory expects the highest standards of scientific integrity to be adhered to by the researchers, students and other staff that it funds, whether they are employees or associates of other institutions. ...

... This routine is designed to read in the current correlator set-up, go to the chosen source, and then take data pointing directly at the specified source. This routine will automatically wait until you are on source before beginning to take data. ... Additionally, this routine allows you to take an ON/OFF calibration pair (one 10s scan with the noise diode on, followed by a 10s scan with the diode off), using the chosen noise diode configuration (see Section 1.6 . ...

Next: Infrared Data Up: Contents Previous: Optical Photometry . ... For example, one method is to derive the spectral energy distribution (SED) for a target star and compare it to the SED of a dereddened standard star. ... Temperature can be determine via the B - V color (Gilliland 1985): . ... The results produced small extinctions to the background stars of between A and A . ... The most accurate extinction calculation requires both IR and spectral data. Infrared Data . Spectroscopic Data . ...

... This gives a nice opportunity to check the quality of the FIRPO photometry against that of TIRGO. ... The values are Program POLYFIT V 10/Jul/90 ( A.Richichi ) - 24-Aug-1997 13:38:25 File : diff_temp_jc.dat Pol. degree: 1- N = 10- [ 2786.00- 4095.00 ] - [ 0.00- 1194.00] 1 -.10304E+01 0.26412E+00 2 0.29958E-03 0.74406E-04 sdev: 0.16063E+00 chi2 :0.24486E+01 Program POLYFIT V 10/Jul/90 ( A.Richichi ) - 24-Aug-1997 13:42:59 File : diff_temp_hc.dat Pol. degree: 1- N = 10- [ 2786.00- ...

Last updated 5 November 2003 by JMD . Last link checked 9 October 2003 by JCB . Data from 191 observations of stars with the ARCES were analyzed to calculate exposure times to reach particular signal-to-noise values for bright standard stars. ... An exponential fit to the data shows pretty good agreement and allows for forecasting to fainter stars beyond the limit of the data set ( V ~ 12). The fit was used to calculate the exposure times in the table below: . ...