## Simon Jeffery's Software Store

## Library Documentation

## PHOT

This library currently provides subroutines used to transform theoretical spectra to intermediate and broad-band photometric indices. They have been adapted from Kurucz' programmes and tranlated to Fortran 90. Typical tasks are the response functions and transmission curves for various filters, mirrors and photomultiplier windows.

Language: Fortran 90

## FUNCTION PHOT_1P21 (WAVE)

Provides the normalized response curve of a standard 1P21 RCA photomultiplier. The curve is tabulated in 10nm steps from 300 nm to 600 nm and is normalized at 400nm. Uses linear interpolation. The response is zero outside the given wavelength range.

WAVE real input Wavelength in nanometres PHOT_1P21 real output Normalised response function

## FUNCTION PHOT_AIR (WAVE,ATMOS)

Provides the atmospheric transmission coefficient for a given air mass at a given wavelength. The extinction data is taken from Allen, p. 126, interpolated linearly in wavelengty between 300 and 600 nm, and transformed to a transmission coefficient = exp(- extinction * air mass). Outside this range, or if the air mass is zero, the transmission is set to unity.

WAVE real input Wavelength in nanometres ATMOS real input Air mass PHOT_AIR real output Transmission coefficient

## FUNCTION PHOT_ALUM (WAVE)

Provides the reflectivity of aluminium at a given wavelength. The data is taken from Allen and is interpolated linearly between 300 nm and 600 nm. Values range between 0.82 and 0.89. The reflectivity is set to 0.77 outside the valid wavelength range.

WAVE real input Wavelength in nanometres PHOT_ALUM real output Reflectivity

## REAL FUNCTION PHOT_FILTER (WAVE,FILTER)

Return transmission coefficient for a specified standard filter at a specified wavelength in nanometres. If a filter is not defined, the transmission coefficient is 1.0. Based on data taken from Kurucz' programs. Uses linear interpolation in the tabulated data.

Filters currently available:

Johnson: U B V R I J K L Stromgren: u v b y

WAVE real input Wavelength in nanometres FILTER character*1 input Filter identifier PHOT_FILTER real output Transmission coefficient

## REAL FUNCTION PHOT_RESPONSE ( WAVE, FILTER )

Returns the combined response function for a given wavelength (nm) and filter assuming zero air mass, a 1P21 photomultiplier and an aluminium mirror. Inputs must be valid as for PHOT_FILTER, PHOT_AIR, PHOT_ALUM and PHOT_1P21.

WAVE real input Wavelength in nanometres FILTER character*1 input Filter identifier PHOT_FILTER real output Transmission coefficient

## SUBROUTINE PHOT_LINTER(XOLD,YOLD,NOLD,XNEW,YNEW,NNEW)

## SUBROUTINE PHOT_PINTER(XOLD,FOLD,NOLD,XNEW,FNEW,NNEW)