During 2021 and 2022 I took a good number of subframes focusing on M81 and M82 field and I planned to integrate RGB channels with Ha and Oiii narrowband contribute.
Being a follower of John Rista short time DSO photography approach, RGB channel subframes I recorded at 60″, Halpha and Oiii subframes at 180″, William Optics Redcat51 and ASI1600mm Pro at -20 Celsius, Gain 139.
After standard calibration, cosmetic correction by dark-master, star registration and winsorized sigma clipping integration, I obtained masterframe for each channel recorded.
Channel combination of RGB generated a good integration which I played with Ha and Oiii masters to Dynamic BG removal, solving (and annotated transparent layer version for further work), Spectrophotometric Color Calibration (just RGB) deconvolution and denoising.
I then proceed by starXterminator in starless and stars version of each master to work properly ‘till putting them back by PixelMath, obtaining a pretty good RGB master
with ready-to-go Halpha and Oiii narrowband master to integrate within:
H alpha channel to be associated to R channel while Oiii to differently be integrated with both G and B channels.
Narrowband with RGB integration produced a pretty good result which, in turns, I little worked over separating again stars and starless sub-master, finally directly melted in Photoshop.
This portion of sky is so rich of galaxies; PGC annotation (PixInSight) gives an idea of the richness of field
I thus start to try some crop solution for better framing and focusing the final image. At first I cropped a squared and a vertical version to catch in the field also NGC2976, NGC2961 and NGC2959.
Finally I focused about M81 and M82 with a deep cropping for an orizontal composition, trying to dispose M81 and friends according to 3/4 grids basic composition rule.
Photoshop, non cropped version, with 3 main crops framing as guide layer are available here
According to Stewart Sharpless annotation, 1959 “A Catalogue of Hii Regions” U.S. Naval Observatory, 10 Sept. 1959 [ https://articles.adsabs.harvard.edu/pdf/1959ApJS….4..257S ], Sh2-139 is “Part of II Cep association” a wide and luminous OB spectral type stellar association situated at a distance of about 3.200 parsec, or 10.400 light years, within the Perseus Arm, one of the 2 major spiral arms of our galaxy.
Sh2-132 complex is featured by a bright optical nebula with an intense central region (Ø = 25’) surrounded by more diffuse emission ( Ø ~ 1*). Low resolution radio studies have shown it to be an intense radio source with a strong central core contained into a more diffuse envelope.
Churchwell and Walmsley 1973 analysis confined that the total emission is thermal nature, featured by a spectrum flatted down to 0.408 GHz, typical of a low Hii density region.
Cfr. Churchwell E. , Walmsley C. M. , 1973 “Observation of Optical Nebula at 2695 Mhz ” in Astron. Astrophys. 23: 117
Nebula analysis shows two distinct regions separated by an area, running from NW to SE, with little or no emission.
The optical emission in the eastern region is quite mottled, with areas of bright emission and patches of obscuring materials. Western region is instead featured by little or no obscuring matter.
Strong central features and western/eastern regions strong/weaker emission are confirmed by radio analysis at 0.408 GHz and 1.4 GHz conducted respectively by Felli et al. 1977a and Felli and Churchwell 1972.
According to Van der Hucht 2001 and Hamman et al. 2006 among those very hot and massive stars responsible for the ionization of gasses, notable consideration have to be taken about two Wolf-Rayet subjects, known as HD 211564 and HD 211853 (or WR 153), featured by a huge bubble well visible in radio emissions identified as Shell B, which scholars suggest to be originated from strong stellar wind from these massive star, featured after Harten et al. 1978 study by a non uniform emission specially on the eastern side where there is essentially no emission at all.
Similar smaller structure, named Shell A, bubbles around a class K star.
According to Dubout-Crillon 1976 catalogue, lion’s bottom and tail shaped like portion is made by a thin strip of emission extending to the south of the eastern region featured by a faint Halpha ridge.
Harten et al. 1978 studies of radio emission of this Hii region results indicated that 2/3 of the radio emissions originates in features larger then 10’ in diameter, suggesting that total mass and low electron density placed Sh2-132 as a member of evolved giant Hii region.
Helou and Walker studies of infrared sources identified and cataloged within the nebula nine sources of infrared radiation, while Wouterloot and colleagues 2013 identified an H2O maser source.
Wouterloot, J. G. A.; Brand, J.; Fiegle, K., IRAS sources beyond the solar circle. III – Observations of H2O, OH, CH3OH and CO, in Astronomy and Astrophysics Supplement Series, vol. 98, n. 3, maggio 1993, pp. 589-636. URL consultato il 21 marzo 2013. https://ui.adsabs.harvard.edu/abs/1993A%26AS…98..589W/abstract
The development of infrared astronomy gives chances to scholars like Saurin and colleagues 2009 to explore Sh2-132 Hii regions and studied its Hii region as a star forming region and embedded star clusters complex.
Grounding on Harten et al. 1978 radio continuum emission as indication of giant nature of this complex and its evolved character, Saurin hypothesized that Sh-132 could be suitable laboratory for early dynamical and hydrodynamical evolution, and by R-band Digitalized Sky Survey imaging of the whole complex they confirm 2 previous identified open cluster
Teutsch 127a – optical embedded open cluster, includes Trap 900
and Berkley 94a – optical open cluster on the outskirts of the complex
And discovered 4 new open cluster:
SBB1 – infrared embedded cluster with IRAS 22172+5549,
SBB2 – optical embedded cluster with bow-shock
SBB3 – Compact optical open cluster surrounding WR 152
SBB4 – Optical open cluster on the outskirts of the complex.
Sh2-129 emission nebula presents an irregular ring-arch form which resemble a figure of a flying bat, and according to Blitz et.Al. is situated at a distance of about 400 parsec or 1300 light-years.
According to Dobashi and collegues the region sourroundig Sh-129 is particularly rich of molecular clouds, first among all the whide obscure nebulositys system occulting the Milky Way in the direction of Cefeus; cfr. Dobahashi K. et Al., 1994 “Molecular Clouds in Cygnus. I. A Large-Scale 13CO Survey” – https://ui.adsabs.harvard.edu/abs/1994ApJS…95..419D/abstract
George Helou and collegues [ https://ui.adsabs.harvard.edu/abs/1988iras….7…..H/abstract ] studied the infrared radiation source IRAS 21168+5948 which coordinates coincide with the CO emission region, as just introduced within Avedisova Star Formation regions Catalogue; cfr. Avedisova V. S., 2002 “A Catalog of Star-Forming Regions in the Galaxy” in Astronomy Reports, vol.46 n.3: 193 – 205.
Within Sh2-129 center, recording in Oiii narrowband, is possible to enhance the vision of Ou4 nebula, whose form gave the name of squid nebula.
Discovered in 2011 by French astro-imager Nicolas Outters, the Squid Nebula’s alluring bipolar shape is distinguished by the telltale blue-green emission from doubly ionized oxygen atoms. Though apparently completely surrounded by hydrogen emission region Sh2-129, the true distance and nature of the Ou4 have been difficult to determine.
Recent investigation suggests Ou4 really does lie within Sh2-129 some 2,300 light-years away. Consistent with that scenario, Ou4 would represent a spectacular outflow driven by HR8119, a triple system of hot, massive stars seen near the center of the nebula.
The truly giant Squid Nebula would physically be nearly 50 light-years across.
This work is the result of personal SHO records using William Optics Redcat 51 and ASI1600mm Pro under Bortle 6 sky in Livorno – Italy (home balcony) with integration of records focused about Oiii signal obtained by Takahashi FSQ-106EDX4 and Proline FLI PL16083 camera retrieved from Telescopelive.
Data framelists set available:
here for WO51,
and here for Takahashi106
PixInSight cored workflow for generate 2 distinguished single channel SHO masters, linear-fit by Takahashi Oiii master, each pair blended by pixelmath within final S H and O masters, channel-combined in the SHO integration.
Normal narrowband workflow post-proccessing followed ‘till reaching an SHO starless
and SHO stars separated masters.
The same workflows I took for RGB channels, with the focus on star – separated from starless final integration to be used for final image composing.
I then integrated in Photoshop by screen blending mode after necessary fixing and adjustements.
Parallely, the same workflow I made for Oiii master, using Oiii starless for enhancing Ou4 structure, luminosity and tones, in Photoshop by adjustements and colorizing filtered layer.
Integration of Oiii starless channel within SHO master enhanced luminosity, saturation and structure of Ou4 whole nebula.
SH2-157, the Lobster Claw Nebula, is an emission nebula located about 11,000 light-years away in the constellation of Cassiopeia.
According to SHO palette, red/orange and predominantly yellow regions of the nebula evinced a very large H II region while the blue-colored are predominately regions featured by the emission of light from molecular oxygen.
On the top NGC 7635 – the Bubble Nebula, and on the middle the star cluster NGC 7510.
Telescopi O Obiettivi Di Acquisizione: William Optics Redcat 51 Camere Di Acquisizione: ZWO ASI1600MM Pro Montature : Sky-Watcher EQM-35 × Filtri: Astronomik H-alpha CCD 6nm · Astronomik OIII CCD 12nm 1.25″ · Astronomik OIII CCD 6nm · Astronomik SII CCD 6nm Accessori : ZWO ASIAIR Plus · ZWO ASIAIR Pro · ZWO EAF · ZWO EFW 8 x 1.25″ / 31mm Software: Adobe Photoshop · Pleiades Astrophoto PixInsight Telescopi O Obiettivi Di Guida : QHYCCD Mini Guide Scope Camere Di Guida : ZWO ASI120MM Mini
Dettagli d’acquisizione Date: 09 Dicembre 2021 · 11 Dicembre 2021 · 12 Dicembre 2021 · 13 Dicembre 2021 · 15 Dicembre 2021 · 16 Dicembre 2021 · 17 Dicembre 2021 · 18 Dicembre 2021 · 08 Gennaio 2022 · 09 Gennaio 2022 · 10 Gennaio 2022 · 11 Gennaio 2022 · 12 Gennaio 2022 · 13 Gennaio 2022 · 14 Gennaio 2022 · 16 Gennaio 2022 · 18 Gennaio 2022 · 22 Gennaio 2022 · 23 Gennaio 2022 · 24 Gennaio 2022 · 28 Gennaio 2022 · 29 Gennaio 2022 · 31 Gennaio 2022 · 01 Febbraio 2022 · 02 Febbraio 2022 · 05 Febbraio 2022
Pose: Astronomik H-alpha CCD 12nm 1.25″: 79×180″(3h 57′) (gain: 139.00) -20°C bin 1×1 Astronomik OIII CCD 12nm 1.25″: 62×180″(3h 6′) (gain: 139.00) -20°C bin 1×1 Astronomik SII CCD 12nm 1.25″: 77×180″(3h 51′) (gain: 139.00) -20°C bin 1×1 Integrazione: 10h 54′ Dark: 33, Flat: 33, Dark dei flat: 33 Giorno lunare medio: 12.35 giorni Fase lunare media: 58.64% Scala del Cielo Scuro Bortle: 6.00
Reprocessing 2022 records focused about M42 region. In this work there’s a main core in LRGB, background removed, SPColorCalibrated, Deconvoltued and denoised is then integrated and boosted by Ha and Oiii narrowband master (Bgremoved, Deconvoluted and denoised) with Ha applied to L and R channel, Oiii to Green and Blue. Final starless and 0.65 stars pixelmath blended and Photoshop retouches.