NGC104 (47 Tuc) under a 70% waxing Moon

[Startrek (Martin)]

Captured a quick hour on 47 Tuc Sunday night with the new ZWOASI2600MC at my weekender before the clouds rolled in around 10pm.A 70% waxing moon overhead.I was going to run 60 sec subs as I wasn’t sure whether the core would be too blown out but the 90sec subs seemed ok after processing
8” f5 Bintel newt
EQ6-R mount
ZWOASI2600MC cooled to -15C Ascom control with Highest Dynamic Range Gain 0 offset 10
No filter
42 x 90sec dithered guided subs
15 x darks
No flats
PHD2 guiding at 0.75 to 0.80 arc sec error
Goto and tracking EQMOD StellariumScope and Stellarium
Frame focus and Capture APT
Stacked in DSS
Processed in Startools V1.6 OSC linear data set

Comments welcome

[Jackstar]

That looks great Martin well done. The star colours are fantastic.
i see you dropped the temp down to -15,
did you notice any improvements?


Jack

[PKay (Peter)]

Nice one M

It would be fun to zoom in using the hi res to find a red giant. They are there.

https://apod.nasa.gov/apod/ap150519.html

I found a few in Omega Centauri

[Startrek (Martin)]

Jack
Thanks very much
If you look at the attached graphs , when you drop temperature from -10C to -15c you basically halve your dark current ( which is negligible anyway, you could leave it at -5C as still have extremely low noise )
Also ZWO advised that Unity Gain on these cameras is only a term , actually at Gain 100 you still get good Dynamic Range like Gain 0 ( Highest Dynamic Range ) but you don’t reach near full well capacity in each pixel only around 18,000 e- ( FW is 50,000 e- ) . So to sum up, Gain 100 is fine, your still getting very good Dynamic Range but your not pushing the camera to its full potential especially in those longer exposures.
I did an experiment last night and processed the same image of NGC104 with same processing parameters without “darks” and to me the imaged looked better !!!
This camera is absolutely incredible !!!
Who needs flats , who needs darks !!!

Peter
Thanks
It would be nice to go a little deeper , maybe later on I might consider the 10” f5 but the bigger you go the more you have to consider seeing and transparency
We’ll see

Martin

[Startrek (Martin)]

Jack,
One detail I forget to point out , at Gain 0 on the 2600MC the ADU is 0.76e. The concept of Unity Gain is generally considered by adding 1.0e electron will result in 1.0 ADU of brightness, so in fact this camera does not have a true or generally accepted Unity Gain setting as you cannot go below 0 in Gain
ZWO have just called Gain 0 , Unity Gain in the Ascom window for convenience purposes
My recommendation would be to leave your Ascom setting at Highest Dynamic Range to maximise the potential of the camera full Dynamic Range unless you want to reduce read noise a bit. From using this camera over the past 8 weeks in both heavy light polluted Sydney and my dark skies on the South Coast , the noise produced from this camera is extremely low. Mid Summer will be the real test with long exposures
Hope the above makes sense
Cheers
Martin

[Jackstar]

Thanks Martin,
You have explained that really well.
Next clear time i get i will use the highest dynamic range.


thanks


jack

[LostInSp_ce]

Fantastic image Martin. These new gen cameras look good. Well one!

[Startrek (Martin)]

Originally Posted by LostInSp_ce

Fantastic image Martin. These new gen cameras look good. Well one!

Thanks LIS
The new camera is a win win in every way
Almost no dark current
I’m guiding better as the new camera is 180gm heavier than the old DSLR and my balance has improved
More smaller pixels than the old DSLR same sensor size, greater resolution and detail
Huge full well
Greater dynamic range
In summer the DSLR use to run at +30degC so images were riddled with noise
New camera can be cooled to -35 deg C almost zero noise
QE on the DSLR around 35% New OSC QE over 80%
Etc.......

Martin