The "other" open cluster in Cancer, Messier 67
Messier 67 is less famous than the Beehive cluster (Messier 44) in Cancer but is quite appealing. Estimated age is about 5 billion years old, so very old for an open cluster but spectroscopic analysis of all the stars confirms this. Mostly main sequence stars, some red giants and a few blue stragglers. there are about 500 members in the cluster.
I’ve had a few issues with my 480mm scope recently in terms of guiding and some of the mechanical aspects of the mount. This is a test image of 50 x 5 minutes to play around with some guiding parameters and assess the quality of the stars.
The stars are a bit square suggesting some differential flexure or field rotation between main scope and guide scope. I’ll make sure everything is tightened up and properly aligned then try again.
Technical Card
480/80mm f/6 Altair Starwave triplet refractor.
Altair Planostar 1.0 x FF with 2 inch IDAS P3 LPS filter
ZWO ASI2600MC; 50 x 300 second subs, Gain 100, Offset 25, Temp = -15c.
EQ6 pro mount with Rowan belt drives. EQMOD control. Primalucelab Sesto Senso electronic focuser.
Session control; SharpCap 4.0 on laptop with WiFi link to IPad.
Automated plate solving GOTO.
Automated FWHM multistar focusing every 16 frames. +/- 500 steps at 2s and 578 gain.
20 dark frames
50 flat frames (electroluminescent panel, 1500ms exposure @ 0 gain).
Post processed in PixInsight 1.8.9.
Light Pollution and Weather:
SQM (L) 19.90 at 11pm - first quarter Moon.
Session clear throughout.
Polar Alignment:
Error measured by PHD2= 0.3 arc minute.
RA drift + 1.75 arcsec/min
Dec drift - 0.09 arcsec/min
Guiding:
PHD2 guiding with ZWO ASI290mm/Altair Starwave 206/50mm guider. Every 4th sub dithered.
RA RMS error 0.8 arcsec
Dec RMS error 0.65 arcsec
Astrometry:
Resolution: 1.610 arcsec/px
Rotation: -97.267 deg
Observation start time: 2023-02-26 20:01:51 UTC
Observation end time: 2023-02-27 00:54:44 UTC
Focal distance: 481.58 mm
Pixel size: 3.76 um
Field of view: 2d 47' 42.0" x 1d 52' 5.2"
Image center: RA: 8 51 06.628 Dec: +11 50 16.80
The "other" open cluster in Cancer, Messier 67
Messier 67 is less famous than the Beehive cluster (Messier 44) in Cancer but is quite appealing. Estimated age is about 5 billion years old, so very old for an open cluster but spectroscopic analysis of all the stars confirms this. Mostly main sequence stars, some red giants and a few blue stragglers. there are about 500 members in the cluster.
I’ve had a few issues with my 480mm scope recently in terms of guiding and some of the mechanical aspects of the mount. This is a test image of 50 x 5 minutes to play around with some guiding parameters and assess the quality of the stars.
The stars are a bit square suggesting some differential flexure or field rotation between main scope and guide scope. I’ll make sure everything is tightened up and properly aligned then try again.
Technical Card
480/80mm f/6 Altair Starwave triplet refractor.
Altair Planostar 1.0 x FF with 2 inch IDAS P3 LPS filter
ZWO ASI2600MC; 50 x 300 second subs, Gain 100, Offset 25, Temp = -15c.
EQ6 pro mount with Rowan belt drives. EQMOD control. Primalucelab Sesto Senso electronic focuser.
Session control; SharpCap 4.0 on laptop with WiFi link to IPad.
Automated plate solving GOTO.
Automated FWHM multistar focusing every 16 frames. +/- 500 steps at 2s and 578 gain.
20 dark frames
50 flat frames (electroluminescent panel, 1500ms exposure @ 0 gain).
Post processed in PixInsight 1.8.9.
Light Pollution and Weather:
SQM (L) 19.90 at 11pm - first quarter Moon.
Session clear throughout.
Polar Alignment:
Error measured by PHD2= 0.3 arc minute.
RA drift + 1.75 arcsec/min
Dec drift - 0.09 arcsec/min
Guiding:
PHD2 guiding with ZWO ASI290mm/Altair Starwave 206/50mm guider. Every 4th sub dithered.
RA RMS error 0.8 arcsec
Dec RMS error 0.65 arcsec
Astrometry:
Resolution: 1.610 arcsec/px
Rotation: -97.267 deg
Observation start time: 2023-02-26 20:01:51 UTC
Observation end time: 2023-02-27 00:54:44 UTC
Focal distance: 481.58 mm
Pixel size: 3.76 um
Field of view: 2d 47' 42.0" x 1d 52' 5.2"
Image center: RA: 8 51 06.628 Dec: +11 50 16.80