A Theoretical Investigation of Focal Stellar Images in the Photographic Emulsion and Application to Photographic Photometry
Abstract
Two-dimensional intensity proffles of focal stellar images in photographic emulsions were derived by convolving gaussian seeing distributions with diffraction proffles and emulsion scattering functions. The results predict too low an intensity for large radial distances from the centre of the image, contradicting the assumption that seeing is gaussian. An analytic formula representing observed image proffles combined with an expression for the characteristic curve led to calibration curves for iris photometers. The curves which were based on five physical parameters were tested using photoelectric standards and found to be valid over at least six magnitudes including the plate limit. These parameters can be determined from bright standard stars making it possible to obtain magnitudes of faint stars for which there are no photoelectric standards. In the case of variable background intensity the theory predicts too small an iris diameter for bright stars imbedded in bright background. This is due to neglection of the depth of the emulsion.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- December 1969
- Bibcode:
- 1969A&A.....3..455M