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Imaging Notes and Experience, CCD Session S00013 FWHM Analysis of NGC 7242 Images FWHM Analysis of C/2000 SV74 Images FWHM Analysis of M1 Image Autoguiding Analysis > Images from CCD Session 13
A 30 sec exposures of NGC 7242 was analysed (Image #13002). It showed a FWHM of around 5.5 to 6 arc sec.
A second image from just east of NGC 7242 shows better FWHM of around 4.3 arc secs.
Two 5 minute exposures (#13016 and 13017) show estimated FWHM of around 4.5 arc secs. 13016-17 Annotated
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2 min exposure (#13028) and 5 min exposure (#13030) of C/2000 SV74 show FWHM values of around 4.0 arc secs. 13030
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5 min exposure of M1 (#13044) shows a FWHM of around 5.5 to 6.0 arc secs
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NGC 7242 (5 min exposures)
In following session (series 101) shows oscillation/overcorrection in Y (Dec) corrections.
X (RA) error is generally <= +/-2 arc secs. Y (Dec) error is generally <= 1 arc secs, though a 3 arc sec error occurs at just after 1.1/2 minutes.
C/2000 SV74
Following autoguiding session of 5 min duration (#13030) of C/2000 SV74. X (RA) and Y (Dec) errors are generally < +/- 2 arc secs. A large random error in Y (Dec) occurs at around 0.5 - 1 minue.
Quality of image is relatively good with a FWHM of 4 arc secs.
Detail from following 2 min exposure #13031 shows elongation of stars in Y (Dec) direction. The guiding graph (series 115) , shows Y (Dec) errors of +/- 4 arc secs and X (RA) errors of +/- 2 arc secs.. The larger Y errors nicely explain the star elongation.
Following graphs show autoguiding analyses for three 5 minute exposures of M1
Series 118 shows X (RA) errors of -4/+2.5 arc secs, with Y (Dec) errors of +/-4 arcs. These relatively large errors explain the particularly poor FWHM values associated with the image (5.5 to 6.0 arc secs).
Series 121 shows Y (Dec) errors of +/- 5 arc secs, with X (RA) errors of +/- 2.5 arc secs.
#13100, 13101
Following 5 min guiding session shows large Y (Dec) errors exceeding 5 arc secs.
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