... 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: . ...

... Astrophysics Group . ... COAST . COAST Astronomical Results . ... Surface Imaging of Betelgeuse . ... This page highlights some astronomical results obtained with COAST over the years. These are listed in chronological order (most recent first). ... Measurements of cyclic variations in the angular diameter of Chi Cygni . ... The first infrared image from an aperture synthesis array . ... The images of Betelgeuse below were reconstructed from COAST data taken in early 2004. ...

... The SMS program is a critical endeavor to investigate whether the predictions of standard cold dark matter cosmology are consistent with the observed matter distribution in the Milky Way halo. It is the deepest, most extended search for optically elusive dwarf satellite galaxies and tidal streams to date, covering the entire Southern hemisphere. ... However only a few dwarf satellites have been found around the Milky Way to date - 22 dwarfs compared to 500-10,000 predicted by theory (Klypin et al. ...

... Team . ... The main goal of observations of GRB host galaxies is accumulation of statistics of their spectroscopic and photometric properties. ... The Hubble diagram for 22 GRB host galaxies with known magnitudes and redshifts (GRB 970228, GRB 970508, GRB 970828, GRB 971214, GRB 980613, GRB 980703, GRB 990123, GRB 990510, GRB 990712, GRB 9912008, GRB 991216, GRB 000131, GRB 000210, GRB 000301C, GRB 000418, GRB 000911, GRB 000926, GRB 001109, GRB 010222, GRB 010921, GRB 011121 and GRB011211). ... 600...

... The material in "From Stargazers to Starships" meets several important requirements of the national standards. Pages cited below are from National Science Education Standards National Academy Press, Washington 1995. ... For example: the sections on astronomy not only describe calendars and sundials (including their construction), but also the astronomy of the ancient Greeks, including two different ways in which ancient Greeks estimated the distance to the Moon. ...

... We demonstrate through numerical simulations that model parameters estimated with our technique are essentially bias-free, even when the average number of counts per bin is 1. ... The IW technique avoids such biases by estimating through successive iterations, where for each iteration, j, , and the best-fit parameters are determined by minimization of . ... In our sample, we find that the minimum values and best-fit parameters converge after about 6 iterations. ...

... The results of radio observations of GRB 080319B in the spectral range of 8.45 GHz are presented. ... Key words: Gamma­rays ­ bursts: observations ­ radio: individual: GRB 080319B 1 Intro duction Gamma­ray bursts (GRBs) are the most luminous explosions currently known in the Universe. ... Smooth angular scanning was used not only in GRB 080319B observations, but to specify the primary standard source radio flux density as well (Kharinov et al., ...

... We publish 16 Doppler imaging temperature maps for the years 1994-2002 of the active RS CVn star II Peg. ... Through Doppler imaging we want to study the spot evolution of the star and in particular compare this with previous results showing a cyclic spot behaviour and persistent active longitudes. ... The derived temperature maps are quite similar to the ones obtained earlier with a different methods, the main differences occurring in the spot latitudes and relative strength of the spot structures....

Peremennye Zvezdy ( Variable Stars ) 33 , No. ... The new variable star HD 305629, with a Cepheid-like light curve, is demonstrated, from our optical observations and ASAS-3 data, to actually be an ellipsoidal variable star on a highly eccentric orbit. ... During a systematic search of variable stars in the publicly available ASAS-3 database (Pojmanski 2002), apparent variability was found in the star HD 305629 (10 51 34 35, -60 47 57 4, J2000.0; Fig. ... The light curve and color curves of HD 305629. ...

ON THE IMPACT OF THE GALACTIC ABERRATION ON VLBI-DERIVED PRECESSION MODEL Z.M. MALKIN Pulkovo Observatory Pulkovskoe Ch. ... Corrections to adopted precession rate are usually computed from the linear trends in long-term time series of celestial pole offset (CPO), which are the differences between the measured and the theoretical coordinates of the celestial pole. ... CONCLUSIONS We have estimated the impact of GA on parameters of precession-nutation model derived from VLBI observations. ...