Scientists Build Sun Camera For Carter Observatory

Gisborne Herald, Volume LXXVI, Issue 23043, 6 September 1949, Page 3

Scientists Build Sun Camera For Carter Observatory

A camera has been manufactured by the Dominion Physical Laboratory, Dcparment of Scientific and Industrial Research, for the Carter Observatory. The apparatus has been designed to be used in conjunction with the observatory’s photo-visual telescope and is called a “sun camera.”

The name, while not strictly correct, does correctly imply that the camera will be used to extend the scope of sun photography, and this has been achieved with considerable success. Sun photography in New Zealand up to the present has only been possible to a limited extent and really serious studies could not be made until suitable equipment became available. Along with the extended study of the sun, it will now be posible to embark upon a detailed study of the face of the moon.

The apparatus consists primarily of a “Barlow” lens of negative power used in conjunction with the telescope at Carter Observatory; an adjustable slit, focal plane shutter; reference line; and the normal adjustments for focusing. Provision is made for adaptors to utilise the existing telescope eyepieces for examining small areas of the sun’s face at greater magnification. Three blinds are used in the shutter arrangements; two are adjustable to produce a variable width slit, and the third acts as a cover blind to prevent accidental exposure upon rewinding. The springs for the blinds are under fixed tension. Shutter speeds have been checked by stroboscopic means and give speeds up to 1/1000 second when at minimum slit width. A cell has been provided in which glass filters may be installed to provide for such studies.

Plate holders are of special make (similar to Grafiex type) to take full plate, while adaptors are provided for half plates. To act as base line for reference purposes a fine line is provided which may be swung through 360 degrees of arc and locked in any position. This meridian indicator is most useful for mapping the position of sunspots relative to some fixed equator. Provision is made to focus the apparatus with relation to the telescope by means of easily operated rack and pinion motions.