Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: The Thing on Dec 09, 2019, 21:05:08

Title: Half of NGC 1499 The California Nebula, 2 Dec 2019
Post by: The Thing on Dec 09, 2019, 21:05:08
First successfulish light with this scope This is not the best as I got the flattener spacing wrong so the stars are not to be looked at too closely. However I am very happy with this and next time I go to California I will rotate the camera and maybe get it all in! The 600 subs I got on the following night are much much better and I hope to process them tomorrow.

60x60s subs, gain 300, offset 10, 10xFlats, 10xDarks, No bias or flat darks.

Image date, time and location:   2019-12-02 Manche, France
Telescope aperture and focal ratio:   Sharpstar 61EDPH with flattener
Camera and filters used:   ZWO ASI294MC Pro, Baader Neodymnium 1.25" filter
Processing applied:   Pixinsight (New Weighted Batch Pre-Processing, DBE_BN_PCC_SM_Dcon_MLT_SCNR_Arcsinh_PCC_HDRMT_LHE_DSE_DT_IrfanView 0.5 resample), Darktable (final noise reduction, sharpen, local contrast, complex 'filmic' curves)

(http://gallery.orpington-astronomy.org.uk/albums/userpics/10050/normal_California_Nebula_DBE_BN_PCC_SM_Dcon_MLT_SCNR_Arcsinh_PCC_HDRMT_LHE_DSE_DT_IVresample.jpg) (http://gallery.orpington-astronomy.org.uk/albums/userpics/10050/California_Nebula_DBE_BN_PCC_SM_Dcon_MLT_SCNR_Arcsinh_PCC_HDRMT_LHE_DSE_DT_IVresample.jpg)
Title: Re: Half of NGC 1499 The California Nebula, 2 Dec 2019
Post by: NoelC on Dec 10, 2019, 11:43:32
Very good Duncan
(I can't see a problem with the stars).
fantastic star field behind.
Noel
Title: Re: Half of NGC 1499 The California Nebula, 2 Dec 2019
Post by: The Thing on Dec 10, 2019, 14:43:51
Thanks Noel.

Wait until eagle eyed :raven: Robert and Mark do a close inspection of those stars...  :alien:
Title: Re: Half of NGC 1499 The California Nebula, 2 Dec 2019
Post by: Carole on Dec 10, 2019, 15:46:24
It's a huge target, and if it had been further up the FOV you might have got most of it in.

Very good for a OSC camera as it is rich in Ha and Sii. 

I just wonder whether the colour balance is quite right, as most of the stars are red and the sky background is a bit red.   

Look forward to the next version with the whole nebula in it. I think the bit you have cut off is far more interesting.

Good to have a scope which will increase the FOV, I think mosaics are tedious, especially in the UK with lack of clear skies, and i don't suppose just across the channel they are much better there either.

Title: Re: Half of NGC 1499 The California Nebula, 2 Dec 2019
Post by: The Thing on Dec 10, 2019, 17:23:45
Thanks Carole, it does look redder in the browser than on my desktop for some reason, but its better than green. I did check the balance of the histogram after Photometric Colour Calibration in PI so it should be right.
Title: Re: Half of NGC 1499 The California Nebula, 2 Dec 2019
Post by: RobertM on Dec 12, 2019, 22:36:59
It looks very red on my monitor as well Duncan, are you sure that the background neutralisation worked correctly ?
Title: Re: Half of NGC 1499 The California Nebula, 2 Dec 2019
Post by: Roberto on Dec 17, 2019, 15:11:15
Duncan

It's a great shot but your monitor needs calibration.  Now on to do the other half!

Roberto
Title: Re: Half of NGC 1499 The California Nebula, 2 Dec 2019
Post by: The Thing on Dec 18, 2019, 08:23:44
Thanks Roberto. My monitor is calibrated frequently with a Spyder 5, it's my eyes that need calibrating! I use PIs Photmetric Colour Calibration on the Average Galaxy preset as a matter of course. I also looked the subject up on the web to find one I liked for this but probably it was quite red as well :{.  I find it hard to be consistent. I would like to take the MarkS route and do it mathematically using camera specific factors for each channel. I think I need to be practical though, not being a mathematician, and pick a reference image to compare colour balance to and use the same reference for every image. Possibly I could image a colour test chart or grey card and work out calibration factors from that.