Description of the modified FMI-77 camera used in Kiruna

Picture of the ASC
The roof of the optical laboratory, the allsky camera is seen in the lower left corner of the picture. This camera was originally designed by Finnish Meteorological Institute, FMI in 1977, and modified several times by IRF. The image data is recorded on 16 mm colour film (Kodak Ektachrome 7251).

Overview of the instrument

Picture of the FMI-77 camera
The sky is imaged onto a convex mirror, which is photographed by the 16 mm film camera located above the mirror. This design results in a loss of information in Zenith.

The film camera is controlled by electronics, which exposes the camera at a selected interval, (typically once every minute) synchronizes the exposures with UTC, (using GPS) and advances the film, etc.

Typical exposure time is 4 seconds, but every eighth exposure is four times longer, in order to reveal faint auroras

When the camera not is in use, or during heavy snowfall, a cover automatically closes and protects the mirror.

An electrical heater keeps the mirror free of moist.

Image orientation

Closeup of the mirror
This picture shows the convex mirror viewed almost as the 16 mm film camera sees it (the betalight and camera are at the center of the mirror in a ‘real’ image). The supporting rod for the camera is towards geomagnetic South. The betalights was intended for intensity estimations.

Format of the time display:

The current format of the time display is:

YYYY mm dd HH MM SS EE

YYYY: Year.
mm: Month 01-12 for January to December.
dd: Day of month 01-31.
HH: Hours 00-23
MM: Minutes 00-59
SS: Seconds 00-59
EE: Exposure time (seconds)

In earlier data the time is displayed as follows:

xx YY ddd HH MM SS

xx: Ignore this
YY: Year (19YY).
mm: Month 01-12 for January to December.
dd: Day of month 01-31.
HH: Hours 00-23
MM: Minutes 00-59
SS: Seconds 00-59

Picture of ASC
In this picture the cover is half closed.