SLOPES computes six least-squares linear regression lines for bivariate datasets of the form (x_i,y_i) with unknown population distributions. Measurement errors, censoring (nondetections) or other complications are not treated. The lines are: the ordinary least-squares regression of y on x, OLS(Y|X); the inverse regression of x on y, OLS(X_Y); the angular bisector of the OLS lines; the orthogonal regression line; the reduced major axis, and the mean-OLS line. The latter four regressions treat the variables symmetrically, while the first two regressions are asymmetrical. Uncertainties for the regression coefficients of each method are estimated via asymptotic formulae, bootstrap resampling, and bivariate normal simulation. These methods, derivation of the regression coefficient uncertainties, and discussions of their use are provided in three papers listed below. The user is encouraged to read and reference these studies.
The program EXTINCT.FOR is a FORTRAN subroutine summarizing a three-dimensional visual Galactic extinction model, based on a number of published studies. INPUTS: Galactic latitude (degrees), Galactic longitude (degrees), and source distance (kpc). OUTPUTS (magnitudes): Extinction, extinction error, a statistical correction term, and an array containing extinction and extinction error from each subroutine. The model is useful for correcting visual magnitudes of Galactic sources (particularly in statistical models), and has been used to find Galactic extinction of extragalactic sources. The model's limited angular resolution (subroutine-dependent, but with a minimum resolution of roughly 2 degrees) is necessitated by its ability to describe three-dimensional structure.
This program addresses the question of what resources are needed to produce a continuous data record of the entire sky down to a given limiting visual magnitude. Toward this end, the program simulates a small camera/telescope or group of small camera/telescopes collecting light from a large portion of the sky. From a given stellar density derived from a Bahcall - Soneira Galaxy model, the program first converts star densities at visual magnitudes between 5 and 20 to number of sky pixels needed to monitor each star simultaneously. From pixels, the program converts input CCD parameters to needed telescope attributes, needed data storage space, and the length of time needed to accumulate data of photometric quality for stars of each limiting visual magnitude over the whole sky. The program steps though photometric integrations one second at a time and includes the contribution from a bright background, read noise, dark current, and atmospheric absorption.
What is the best way to pixelize a sphere? This question occurs in many practical applications, for instance when making maps (of the earth or the celestial sphere) and when doing numerical integrals over the sphere. This package consists of source code and documentation for a method which involves inscribing the sphere in a regular icosahedron and then equalizing the pixel areas.
BSGMODEL is used to construct the disk and spheroid components of the Galaxy from which the distribution of visible stars and mass in the Galaxy is calculated. The computer files accessible here are available for export use. The modifications are described in comment lines in the software. The Galaxy model software has been installed and used by different people for a large variety of purposes (see, e. g., the the review "Star Counts and Galactic Structure'', Ann. Rev. Astron. Ap. 24, 577, 1986 ).
Given a model for the Galaxy, this program computes the microlensing rate in any direction. Program features include the ability to include the brightness of the lens and to compute the probability of lens detection at any level of lensing amplification. The program limits itself to lensing by single stars of single sources. The program is currently setup to accept input from the Galactic models of Bahcall and Soniera (1982, 1986).
There are three files needed for LENSKY, the Fortran file lensky.for and two input files: galmod.dsk (15 Megs) and galmod.sph (22 Megs). The zip file available below contains all three files. The program generates output to the file lensky.out. The program is pretty self-explanatory past that.
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