David's Astronomy Pages Images - Session 586 (2015-05-02)

Images (S585)

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Images (S587)

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Session Notes

Vega - A0V Star P Cyg - Star     NGC 6118 - Spiral Galaxy     Photometric Monitoring - Variables   - R CrB, CI Cyg, ER UMa - RZ LMi attempt failed (due to star drift)     Astrometric Monitoring - Nearby Stars   - Barnards Star

- Night session (1.5 hrs duration), aborted when cloud developed   - Session operated under semi-automated control, with remote monitoring from indoors computer.   - Ambient Temperature:  tube temperature fell to -2.5°C (minimum) - CCD operation -30°C (at 63% average cooling).  - Planned objectives of the session were to monitor selected variable stars & nearby stars and to take Spectral images. -

Vega - A0V Star

Vega Spectra Analysis

Vega - Seeing

CCD Image Animation (frames rotated, but not aligned, cropped) 0.11s exposure, 2x2 binning, Half Frame, SA 200 Filter 2015-05-02  00:27h UT (#586051-55) 12" LX200R  (at f/10.4) + ST-10XME (Rotation S586: 184.5 deg) Rotation S286 : 221 deg)

Vega - Raw Spectral Profiles Comparison between 5 individual image profiles and stacked image profile (profiles produced in RSpec)

Profiles from CCD Images Image details as above

0.11s image (at / near saturation)

Stacked CCD Image 5 x 0.11s (aligned, rotated, cropped), 2x2 binning, Half Frame, SA 200 Filter Image details as above

0.2s image (effectively saturated)

Stacked CCD Image 5 x 0.2s (aligned, rotated, cropped), 2x2 binning, Half Frame, SA 200 Filter 2015-05-02  00:04h UT (#586017-21) 12" LX200R  (at f/10.4) + ST-10XME

Vega - Calibrated Spectral Profiles Comparison between profiles from 0.11s and 0.2s image exposures The Red Profile (0.2s) is noticeably flatter in higher intensity regions of the profile due to saturation of CCD Pixels

CCD Image details as above Red Line :  Vega.20150502.im586017-21.av5x0.2s.S Blue Line :  Vega.20150502.im586051-55.5x0.11s.S (Plot produced in RSpec)

Spectral Image / Histogram Plots Comparison between profiles from 0.11s and 0.2s image exposures Plots both displayed with 50000-65535 ADU black-white range

Stacked CCD Image (5 x 0.11s) Image details as above

Stacked CCD Image (5 x 0.2s) Image details as above

Whilst the CCD image values are not reaching near the 65535 ADU mark,  and represent the sum of 4 physical pixels at 1x1 binning, they are photons are 'filling' the pixel bins at a very rapid rate. and are being ? 'absorbed' into the silica of CCD chip somehow rather than being converted into electron count when read.  This process whilst worse with 0.2s exposure, is applying also to the shorter exposure 0.11s images (NB. the shortest exposures possible with my ST-10E Camera is 0.11s/0.12s) The following 90s CCD Image of NGC 6118 taken 6 minutes / 4 CCD reads after the last Vega 0.11s spectral image still shows traces of Vega's first and zero order spectra.

CCD Image (cropped) 90s exposure (single frame), 3x3 binning, C Filter 2015-05-02 00:32 h UT (#586059) 12" LX200R  (at f/10.4) + ST-10XME

Calculated Instrument Response  (IR = raw vega spectra / smoothed a0V library spectra

S586 profile produced using 0.11s exposures of Vega at Alt 50 deg (airmass 1.30) S585 profile produced using 0.2s exposures of Vega at Alt 68 deg (airmass 1.07)

Vega - Corrected Spectral Profile

Vega - Normalised Spectra  (corrected Vega profile / smoothed library a0V profile

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P Cyg -  Star

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NGC 6118 - Spiral Galaxy

NGC 6118 / Herschel II-402 (Serpens)

CCD Image (cropped) 5 x 90s exposure (average combine), 3x3 binning, C Filter 2015-05-02 00:48 h UT (#586064-73) 12" LX200R  (at f/10.4) + ST-10XME

NGC 6118 / Herschel II-402 - Wider View

CCD Image (50% size) Image details as above

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