On 2009.01.17 Joe Garlitz was searching for
asteroids and noted in one 60-second frame a "transient star"
located at 01:05:16.7 +11:00:02.0 (galactic latitude +3.5 deg).
FOV = 6.0 x 5.7 'arc, north up, east left. Left exposure
(03:04:22 UT) shows "transient star" at 01:05:16.68 +11:00:06.2. The
right frame was taken immediately afterward, and due to the
transient star's saturating 6 pixels in the previous image a "ghost"
is present at the same coordinates.
A nearby star has FWHM = 5.7 x 5.7 "arc (EW & NS), and the
"transient star" (TS) has FWHM = 2.7 x 2.7 (SE's = 0.1 & 0.2)
"arc. The TS appears to be a circular Gaussian (neglecting rows and
columns that intersect the 6 saturated pixels) and has a smaller PSF
than the 60-second exposure of a nearby star. A very brief &
bright flash would produce a smaller PSF. At this observing site it
is possible for short exposures to exhibit 2.7 "arc FWHMs.
Therefore, this event remains a possible candidate A-SETI event.
Joe Garlitz observed with a 12-inch telescope, f/5 and a SBIG
ST-402 CCD. The observatory is located at Elgin, Oregon: observatory
Explanatory Note: Gaussian PSFs that are saturated can still
have their FWHM measured thanks to a convenient property of
2-dimensional Gaussian functions (having the same FWHM in all
orientations): Any slice through the 2-dimensional response
function, regardless of offset from the center and regardless of
orientation, is a Gaussian having the same FWHM.
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WebMaster: B. Gary. This site opened: 2013.01.30. Last Update: 2013.01.30