David's Astronomy Pages Notes - CCD Session 13 (2001-12-14)

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Notes (S14)

FWHM Analysis of NGC 7242 Image

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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FWHM Analysis of  C/2000 SV74 Image

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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FWHM Analysis of  M1 Image

5 min exposure of M1 (#13044) shows a FWHM of around 5.5 to 6.0 arc secs

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Autoguiding Analysis

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 (2 minute exposures)

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.

M1

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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