Globular Cluster Messier 3 in Canes Venatici
A Cosmic snowball of Stars.
Mixed weather forecasts tonight - decided I would chance it and assembled scope in back garden. Only got 15 minutes on target before hail shower! Scope quickly capped and disassembled!
Processed the 3 x 5 minute images of Globular cluster Messier 3 anyway. I used generic flats, darks and bias frames from my last session.
This is a mini-galaxy that orbits our own galaxy but it has lost any spiral arms it once possessed to our own galaxy's gravity, leaving just a spherical core of mostly old yellow stars. Sometimes, the stars interact in the dense core and one can steal matter off a neighbour to form a "blue straggler" which behaves like a young blue star.
Its estimated that there 500000 stars in this globular cluster including a large number of RR Lyrae variables that can act as a "standard candle" to measure interstellar distances as the luminosity of these stars varies in a periodic manner with time.
M3 lies about 33900 LY away from Earth.
Equinox ED 900mm f/7.5 scope x0.85 focal reducer.
Modified Canon 80D @ ISO400, 3 x 300 second subs.
SkyWatcher EQ6 pro mount with Rowan belt drive modification.
Guided by PHD2 via PrimaLuce 240mm f/4 guidescope.
Camera Temp: 8-9c
Astrometry:
Resolution: 0.978 arcsec/pxl
Focal distance: 791.17 mm
Pixel size: 3.75 um
Field of view: 56' 41.3" x 47' 40.6"
Image centre: RA: 13 42 11.692 Dec: +28 22 35
Polar Alignment:
QHY Polemaster alignment -
Error measured by PHD2= 0.5 arc minute.
RA drift + 0.98 arcsec/min
Dec drift - 0.12 arcsec/min
Guiding:
PHD2 guiding with ZWO ASI290mm/PrimaLuce Lab 240/60mm guide scope. Every 3rd shot dithered.
RA RMS error 0.67 arcsec.
Dec RMS error 0.48 arcsec.
Personal Notes:
One star had quite a halo but used masked Atrous wavelet method in PixInsight to good effect.
Globular Cluster Messier 3 in Canes Venatici
A Cosmic snowball of Stars.
Mixed weather forecasts tonight - decided I would chance it and assembled scope in back garden. Only got 15 minutes on target before hail shower! Scope quickly capped and disassembled!
Processed the 3 x 5 minute images of Globular cluster Messier 3 anyway. I used generic flats, darks and bias frames from my last session.
This is a mini-galaxy that orbits our own galaxy but it has lost any spiral arms it once possessed to our own galaxy's gravity, leaving just a spherical core of mostly old yellow stars. Sometimes, the stars interact in the dense core and one can steal matter off a neighbour to form a "blue straggler" which behaves like a young blue star.
Its estimated that there 500000 stars in this globular cluster including a large number of RR Lyrae variables that can act as a "standard candle" to measure interstellar distances as the luminosity of these stars varies in a periodic manner with time.
M3 lies about 33900 LY away from Earth.
Equinox ED 900mm f/7.5 scope x0.85 focal reducer.
Modified Canon 80D @ ISO400, 3 x 300 second subs.
SkyWatcher EQ6 pro mount with Rowan belt drive modification.
Guided by PHD2 via PrimaLuce 240mm f/4 guidescope.
Camera Temp: 8-9c
Astrometry:
Resolution: 0.978 arcsec/pxl
Focal distance: 791.17 mm
Pixel size: 3.75 um
Field of view: 56' 41.3" x 47' 40.6"
Image centre: RA: 13 42 11.692 Dec: +28 22 35
Polar Alignment:
QHY Polemaster alignment -
Error measured by PHD2= 0.5 arc minute.
RA drift + 0.98 arcsec/min
Dec drift - 0.12 arcsec/min
Guiding:
PHD2 guiding with ZWO ASI290mm/PrimaLuce Lab 240/60mm guide scope. Every 3rd shot dithered.
RA RMS error 0.67 arcsec.
Dec RMS error 0.48 arcsec.
Personal Notes:
One star had quite a halo but used masked Atrous wavelet method in PixInsight to good effect.