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Sh2-235 in HSSrgb | by Carballada
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Sh2-235 in HSSrgb

Another object from this nice catalogue of faint nebula.

Long integration of 53 hours using two narrow band filters mainly, searching the limits of the equipment and my own process skills.

It's not a popular target probably because is difficult and usually is not showing so much detail due to the high dynamic range, the core is bright, really bright compare with the faint surroundings.


Sh2-235 is the most central and brightest nebula of an H II region known as G174+2.5; it is observed in the direction of the northern part of the Aur OB1 association and includes the nebulae catalogued as Sh2-231, Sh2-232, Sh2-233 and Sh2-235, identified as individual nebulae in the 1959 census of H II regions. Although in the optical images they appear as distinct nebulae, in reality they all belong to a single giant molecular cloud, of which some parts appear illuminated by young and hot stars. This cloud is located in Perseus' Arm at a galactic latitude that places it slightly off-center with respect to the center of the galactic disk; the distance measurements indicate a range between 1600 and 2000 parsec, so it is normally indicated as about 1800 parsec (5870 light years).


(descri. credits to


Technical card

Imaging telescope or lens:Altair Astro RC250-TT 10" RC Truss Tube


Imaging camera:ZWO ASI1600MM-Cool


Mounts:Mesu 200 Mk2, Astro-Physics Mach-1 GTO CP4


Guiding telescope or lens:Celestron OAG Deluxe


Guiding camera:ZWO ASI174 Mini


Focal reducer:Riccardi Reducer/Flattener 0.75x


Software:Pleiades Astrophoto PixInsight , Seqence Generator Pro


Filters:Astrodon O-III 36mm - 5nm, Astrodon S-II 36mm - 5nm, Astrodon R Gen.2 E-series 36mm, Astrodon G Gen.2 E-series 36mm, Astrodon B Gen.2 E-series 36mm, Astrodon HA 36mm - 5nm, Astrodon L Gen.2 E-series 36mm


Accessories:ZWO EFW, MoonLite NiteCrawler WR30


Resolution: 2328x1760


Dates:Dec. 25, 2019, Jan. 3, 2020, Jan. 12, 2020, Jan. 15, 2020



Astrodon B Gen.2 E-series 36mm: 90x30" (gain: 75.00) -20C bin 1x1

Astrodon G Gen.2 E-series 36mm: 90x30" (gain: 75.00) -20C bin 1x1

Astrodon HA 36mm - 5nm: 186x600" (gain: 200.00) -20C bin 1x1

Astrodon R Gen.2 E-series 36mm: 90x30" (gain: 75.00) -20C bin 1x1

Optolong SII 6.5nm 36mm: 121x600" (gain: 113.00) -20C bin 1x1


Integration: 53.4 hours


Avg. Moon age: 18.25 days


Avg. Moon phase: 55.61% job: 3224550


RA center: 5h 41' 5"


DEC center: +35° 49' 58"


Pixel scale: 1.007 arcsec/pixel


Orientation: 90.283 degrees


Field radius: 0.408


Locations: AAS Montsec, Àger, Lleida, Spain


Data source: Own remote observatory


Remote source: Non-commercial independent facility

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Uploaded on February 5, 2020