[Aavso-photometry] FITS Stack results:

[Jean-Claude PELLE]

Software ImageCCD 3.12

Given:

# DATE_OBS                EXPOSURE
1 2005-01-02T04:49:34.00    20.0
2 2005-01-02T04:50:04.00    20.0
3 2005-01-02T04:50:34.00    20.0
4 2005-01-02T04:51:05.00    20.0
----------------------------------

Hereafter are the relevant keywords in the FITS header, including
the automatically inserted comment for each keyword:

Results are *not* dependant on the order in which the images are processed.

The keyword 'DATE-MID' contains the barycenter of the summed exposures.
There is no need for the exposures to be equally spaced in time.


DATE_OBS= '2005-01-02T04:49:34.00' / Date and time start
DATE-MID= '2005-01-02T04:50:29.25' / Date and time (UT) mid exposure (composite)
MJD-OBS = 53372.2017274            / Modified Julian Date of midtime of observation
DATE-END= '2005-01-02T04:51:25.00' / Date and time end last image
EXPOSURE=               80.000 / Total exposure in seconds
EXPTIME =               80.000 / Total exposure in seconds
NCOADDS =                    4 / Number of coadded frames
SNAPSHOT=                    4 / SnapShot count  
EACHSNAP=               20.000 / Each exposure in seconds


Discarding the third image (04:50:34)

DATE_OBS= '2005-01-02T04:49:34.00' / Date and time start
DATE-MID= '2005-01-02T04:50:24.33' / Date and time (UT) mid exposure (composite)
MJD-OBS = 53372.2016705            / Modified Julian Date of midtime of observation
DATE-END= '2005-01-02T04:51:25.00' / Date and time end last image
EXPOSURE=               60.000 / Total exposure in seconds
EXPTIME =               60.000 / Total exposure in seconds
NCOADDS =                    3 / Number of coadded frames
SNAPSHOT=                    3 / SnapShot count  
EACHSNAP=               20.000 / Each exposure in seconds

DATE_OBS (Date and time start) and DATE-END (Date and time end last image)
remain unchanged as they must be.


Jean-Claude PELLE
Southern Stars Observatories