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Due to the poor UK weather I hadn't been paying much attention to how my automated imaging set up was progressing with this target. So, I was a little surprised when I discovered that it had been very slowly capturing data of this target for the past 6 months........Anyway, here's the result of 32 hours integration time of my first attempt at the Cave nebula (SH2-155).
The LRGB image below has an Ha blend into the L and Red channels and was taken with my Esprit 150.
L: 20, R:13, G:23, B:15, x600s, Ha: 41x1800s, DARKS:30, BIAS:100, FLATS:40 all at -20C.
By lux eterna
This one is a composite from two of my telescopes :
TS APO with reducer = FL 550mm F5.1 iso 800 : 13x20 min Ha + 6x20 min OIII
TS Imaging Star 71 = FL 350mm F5 iso 200 : 82x3 min RGB (only Hutech IDAS LPS-D1 used)
I am new to NB processing, so I followed this tutorial but also improvised some.
Weather did not permit more OIII data, so I squeezed as much as I could out of it. To start with, I only used the green channel from those subs because that channel had the strongest signal.
Filters are Astronomik 2" 12nm. Today I would have used iso 200 even for the NB pics, not 800, since I just learned that 200 is the optimal setting for my (dual) Nikon D7000´s.
The small APO was attached to the HEQ5 Pro CW bar so imaging was done with both scopes simultaneously. 3 minutes exposures is max for the secondary camera due to some remaining flex in that part of the rig which I have not (yet) managed to cancel out.
Stars removed with Straton, then the Ha/OIII image and the wide field RGB image were aligned with Registar and blended together in PS.
All C&C is most welcome.
Here's my latest effort with my new kit, taken in September:
15x600s Ha, 10x420s L, 9 each x300s R, G and B, all 1x1 binned. Equipment as per sig, processed in Pixinsight. My second attempt at combining Ha with LRGB data, and I think it worked a bit better this time.
The Cave Nebula (Sh2-155) is a diffuse nebula in the constellation Cepheus, within a larger nebula complex containing emission, reflection, and dark nebulosity. It is an ionized H II region with ongoing star formation activity, at an estimated distance of 2400 light-years. It has been suggested that radiation from the hot O-type star HD 217086 is compressing the region, triggering the formation of a new generation of stars. The bright red part of the Cave is light emission from excited Hydrogen gas, with some reflection of starlight also present. The region is partly obscured by dark foreground clouds of dust and gas. The name "Cave Nebula" was coined for this object by Patrick Moore, presumably derived from photographic images showing a curved arc of emission nebulosity corresponding to a cave mouth.
Hope you enjoy !
Due to clouds and/or moon I have been forced to settle for processing data of various quality from this autumn. I found 1 hour of data from a rather misty night of the cave nebula (6 x 10 min with my 5" ES Apo refractor and Canon 60Da). The colours were rather pretty but it was lacking detail both due to the low amount of data and the mist that night. So, I had given up on the image when I stumbled on a site mentioning the Mikulski Archives for Space Telescopes from which monochrome (red or blue filtered) images could be downloaded from various surveys (Palomar Observatory). So, I pushed in the coordinates for the Cave Nebula and downloaded a red filtered image from the Palomar Observatory Space Survey II (POSS2). After some stretching and fixing with orientation and pixel size I used it as a Lum layer (all done in PS), and here is the result.
Yes, I know, it is borrowed data but at least the colours are mine and it was a fun exercise.....
I post my RGB image, the POSS2 download, and the final mix.
Any comments most welcome!