Plate.ExposureStartTime Property

Plate.ExposureStartTime (read-write, Double)

The UTC start time of the exposure (Date, FITS keyword DATE-OBS)

Syntax

Plate.ExposureStartTime [= Double]

The property syntax has these parts:

Part	Description
Value (Double)	The UTC start time of the exposure (Date, FITS keyword DATE-OBS)

Remarks

This correspnds to the DATE-OBS field in the FITS file. If DATE-OBS is not present, and the (deprecated) combination of DATE and TIME-OBS (or UT) is present, the latter will be used. If DATE-OBS has no time (non ISO format) but does have a date, PinPoint will use this in preference to DATE.

Whether or not DATE-OBS is present in the original image file, Plate.UpdateFITS() or Plate.WriteFITS() will add a standard ISO 8601 (so-called Y2K) compliant DATE-OBS field to the FITS header, as well as update the deprecated DATE and TIME-OBS records. If the original image does not have any exposure start time info in it, yet it is set by a client via the Plate.ExposureStartTime property, Plate.UpdateFITS() or Plate.WriteFITS() will still add DATE-OBS, DATE and TIME-OBS.

Fractional seconds are supported in the DATE-OBS field. If fractional seconds are present in the DATE-OBS field of the original file, or in the value set via the Plate.ExposureStartTime property, the DATE-OBS field will be written with three decimal digits precision (milliseconds). If the seconds value is within one half millisecond of zero, the ".000" is automatically supressed. This is done for maximum compatibility with some amateur software packages that cannot parse the full ISO format with decimal digits on the seconds part.