Computation of the shift by the ‘inflexion points’ method (Program FLEXPT) Again the analytical form of the 4th degree polynomial gives a simple expression for the shift measured by this method. We require for an inflexion point This is a quadratic equation possessing rootsand the midpoint of the line joining the inflexion points has avalue […]

# Radial Velocities In The Zodiacal Dust Cloud

## Interpretation of results in terms of physical models (Zodiacal Dust Cloud) Part 1

In this topic, I present the fully compensated averaged scans obtained in the two observing periods, 1971 and 1972, for all observed elongations, each with a fitted Gaussian curve, except as noted. From parameters derived from these fits, plots of average wavelength shift, line width and line depth against elongation are constructed. These observations, the […]

## Interpretation of results in terms of physical models (Zodiacal Dust Cloud) Part 2

General comments on the data All the averaged experimental scans show a major absorption feature in the neighbourhood of 5183.6 A. In three cases, there is a hint of a second small absorption line, towards the red. A curious property of the data is that the scans tend to be of less overall height at […]

## Interpretation of results in terms of physical models (Zodiacal Dust Cloud) Part 3

Other considerations in rotating models This discussion of the rotating dust cloud model has so far focussed on adjusting the p parameter to fit the results. Other parameters may also produce a change in shape of the curves. The number density was assumed to be proportional to r-a, where r is the distance from the […]

## Interpretation of results in terms of physical models (Zodiacal Dust Cloud) Part 4

Comparison of continuous flow model with experiment The model gives a good fit to the experimental values for the September-October 1971 period for the high elongations where the rotating model failed to provide a satisfactory fit. At low elongations in the morning the rotating model gives a better agreement, and at low evening elongations there […]

## Interpretation of results in terms of physical models (Zodiacal Dust Cloud) Part 5

Further analysis of the data by comparison with new radial velocity data and model theory available in 2007 As discussed in topic 1, there have been long periods of inactivity in Doppler studies of the ZL since 1974. Nevertheless, some interesting results have now been added to the data in this field, and it is […]

## Current developments and future plans (Zodiacal Dust Cloud)

In this topic, I will briefly review the experiments currently planned, or in operation, in Solar System Astronomy: rocket-borne, space-borne, and ground-based observations, which are likely to throw new light on the structure and nature of the Sun’s dust cloud. I will also touch on present unresolved issues which warrant attention, and sketch plans for […]

## Program ZLPLT (Zodiacal Dust Cloud)

Program to process a night’s raw data, subtracting the dark count, dividing out the premonochromating filter, dividing by the compensation channel count, and outputting the fully reduced scans on to cards.

## Programs which fit curves to the fully reduced data points (Zodiacal Dust Cloud)

LSQFIT accepts the punched card fully reduced data and calculates a least-squares fitted polynomial curve of any specified order (to a maximum of six, in this case). Output is on cards, to be read as input by the programs in topic 2, which plot the curves and estimate the mean wavelength shift. GAUSSN accepts the […]

## Programs which draw the fitted curves and extract parameters from the fits (Zodiacal Dust Cloud)

POLYPT accepts the output cards from LSQFIT as input, for any order polynomial, plots the experimental points (xi, yi) and draws the curve of the polynomial, by calculating its value at 1/20th angstrom intervals from the coefficients. FLEXPT accepts the output cards of LSQFIT, for 4th order only, and calculates the mid-point of the line […]