The Lambda star cluster (IC 2944) and the Running Chicken emission nebula (IC 2948).
I think I considerably under-exposed this image. The cluster shows up reasonably well but there is considerably more nebulosity available than I managed to draw out in post-processing.
One of the features of the SharpCap Pro image acquisition software is the ability to advise on the best exposure levels suited to this particular night sky with that particular CMOS camera. I’m slowly beginning to get the hang of SharpCap but I goofed a bit this time and the image was disappointing.
It may look complex but this SharpCap graph simply indicates that the optimal exposure I should use have used with my ZWO ASI071 camera that night was 31.6 seconds with a gain setting of 92.
It also clearly indicates that long exposures of several minutes (as CCD camera users would be required to use) would not have been useful for this camera in this light polluted sky.
After trying it, I reduced the exposure period to 25 seconds, because – in my naivity – I thought it was over-exposing. I ended up regretting it because the reduction of about 20% actually underexposed the image.
Next time I might follow the instructions…. 🤓
|Constellation||Centaurus||Altitude:||45° above SSE|
|Diameter||111 light years||Distance||5,900 light years|
|Exposure:||25.9s x 142 live stacked||Gain:||92|
|Date||2019-02-11||Time:||approx 11.30 pm|
|Cloud:||Mostly clear.||Moon:||33% set aprox 11.30 pm|
|Acquisition:||SharpCap live stack.||Processing:||GIMP|
|Telescope:||Skywatcher Esprit 120ED||Type:||APO triplet refractor|
|Focal:||840 mm F/7||Mount:||SkyWatcher EQ6-R Pro|
|Camera:||ZWO ASI 071 MC Pro||Type:||CMOS 28.4mm 16 Mpx|
|Optical aids:||Flattener: yes; filter: no.||Guiding:||No|
|Polar aligning:||QHYCCD PoleMaster||Polar Error:||03’ 15”|
Link to annotated astrometry image.
[ZWO ASI071MC Pro]
Output Format=PNG files (*.png)
Frame Rate Limit=Maximum
White Bal (B)=50
White Bal (R)=53
Auto Exp Max Gain=300
Auto Exp Max Exp M S=30000
Auto Exp Target Brightness=100
Anti Dew Heater=Off
Subtract Dark=C:\Users\Roger\Desktop\SharpCap Captures\darks\ZWO ASI071MC Pro\RAW16@4944×3284\25.9s\gain_92\dark_20_frames_-12.3C_2019-02-09T10_58_25.png
Display Black Point=0
Display MidTone Point=0.5
Display White Point=1
Images © Roger Powell
If all else fails, definitely read the instructions. But without trial and error where is the spirit of adventure?