M45 - At last a clear night

[nexusjeep]

Well the rain has finally stopped so got out to use the scope and try the new mechanised polar alignment which worked really well quickly got to 2 seconds of error so thought that's close enough and started imaging. The shot below is the best 64 x 3 min subs out of 72.

Image Info :

Imaging kit : APM-LZOS 130/780 + 0.75x MR Reducer/flattener, ASI2600MC-Pro + Esatto 4" Focuser
Mount : M-UNO Synscan
Guide : Skywatcher ED72Pro+0.8x reducer Altair 290M guide camera
Software: SharpCap, GSS Mount control software, PHD2, Stellarium, AstroPixelProcessor, Affinity Photo 1.9

Image 64 x 180s at 100g -10C / 25 Darks / 50 Flats / 100 Bias

23.10.13 M45_Pleiades 64 x 3min subs by Nick Davis, on Flickr

Thanks for looking
Cheers
Nick

[admin]

Hi Nick,

yes, it did clear quite nicely last night after the rain moved across, although the temperature sunk like a stone too... I popped out briefly to take some of the most boring astrophotos ever of the region around the celestial pole for some experiments I want to do on polar alignment improvements

I do like your M45 image a lot - the nebulosity has come out very nicely, which I know can be a challenge

cheers,

Robin

[mixon]

Hello Nick -
Couldn't help but notice what a beautiful image of the M45. I'm new beginner @EAA. I have recently acquired a new rig/ EQ mount and scope. I started off with ALT/AZ Go-To mount Celestron Next star 650 mm FL f/5. Imaging planetary for about 6 months.
Recently I just started experimented with DSO imaging.

Quick question - what was the total acquisition time for all Light, Dark, Flats and Bias frames? It looks like your light frames were a total of 3 hours ? I'm trying to understand all this stuff, huge learning curve involved.

Again, very nice image. Thanks for sharing.

[nexusjeep]

Hi Mixon,
Thanks for the compliment the break down is as below

lights I took 72 3mins in total so 3hr 36mins then in Astro Pixel Processor (APP) ditched the 8 that were low in quality score so the integration image is 3 hrs 12mins as posted.

For calibration I used 25 x 3 minute darks but these only need to be taken once as you end up with a master dark in APP so for all future integrations you just use that and never take them again. Also the ASI2600MC Pro has no amplifier glow so you are only dealing with hot /cold pixels so I actually use my 3 minute master dark for all time periods and with the dithered data have never had a calibration issue with it ranging from 15s to 5 minute subs.

Bias frames were 100 x fastest speed possible on the camera again these are only ever done once as I always work at 100 gain as this is the optimum for this camera and again after the first time in APP you end up with a master bias which can be used on subsequent integrations.

Flat frames were 50 x 1.5s I can shoot these faster but I get a better flat giving the sensor longer to settle, I use a Geoptik flat field generator that I have added extra diffuser discs to so I can run it brighter on the light source and the extra diffusers still allow me to get the 1,5s sub @ 100 gain. I shot my flats first thing in the evening after doing an initial focuser and store the subs but also have SharpCap generate a master that I then use through the evening in the live stack.

Flat darks I shoot the same 50 x 1.5s @ 100 gain but I only do these once and keep them as a master set as they are not recording any light as such only sensor noise so this is not changing session to session.

Think that's everything if I have missed something let me know and I will do my best to answer.

Cheers
Nick