Monthly Archives: July 2015

NGC 1491 | SH2-206 – an emission nebula in Perseus

NGC1491v1.7cNGC 1491 (also designated Sharpless SH2-206) is a bright emission nebula and HII region, located on the edge of a vast cloud region of neutral gas, about 10,700 light-years away in the Perseus arm of our Milky Way galaxy. The stellar wind from the O5V 11.2 magnitude star (BD +50 886) at its centre is forming a blister in the gas clouds immediately surrounding it while also eroding the gas clouds.

HII regions are well known for being places where new stars are born, and are created when ultraviolet radiation from hot stars ionizes the surrounding gas, causing it to glow in visible and infrared light. This is a faint nebula and required over nine hours of integration time at each emission line to reveal the detail across the entire nebula.

MaxIm DL v6 was used to calibrate, align and stack the sub exposures. PixInsight v1.8 DBE (Dynamic Background Extraction) was used in the absence of suitable flat frames to remove sky background noise and gradients. Photoshop CC 2014 layers and layer mask processing techniques were used for colour enhancement and to tease out the detail – Levels, Curves, Reduce Noise, Selective Color, HDR toning, Smart Sharpen and Unsharp Mask in predominant use.

Right ascension: 04h 03m 14s | Declination: +51° 18′ 58″ | Distance: 10,700 Light Years
Field of view: 54 x 37 arcmin

Camera: SBIG ST-10XME
Telescope: APM 152-1200ED F/6.2 with Riccardi x0.75 Reducer
Guiding: Off-axis with Lodestar guider
Filters: Astrodon Ha (3nm), OIII (3nm), SII (3nm)
Exposures: Ha 28 x 20 min, OIII 27 x 20 min, SII 29 x 20 min
Total exposure: 28 hours
Image composition: False Colour Hubble Palette (SII, Ha, OIII mapped to RGB)
Scale: 1.49 arcsec/pixel
Image acquired: 23rd November 2014 – 6th February 2015

Image capture with MaxIm DL, FocusMax, ACP; Image processed with MaxIm DL; PixInsight; Photoshop CC 2014

TS Photoline 60mm FPL-53 doublet for wide field imaging

TS60ED-wI am now experimenting with a short focal length 60mm refractor for wide field imaging having given up on camera lenses. This is the Telescope Service Photoline 60mm compact apochromatic refractor in combination with the matching Photoline 0.79x reducer. The objective is a 60mm apochromatic ED doublet lens with a FPL-53 element by Ohara Japan. With a native focal length of 330mm the scope has a focal ratio of F/5.5. Using the Photoline 2 inch 0.79x 4-element reducer / corrector the focal length is reduced to 260mm and the scope is transformed into a F/4.2 astrograph.

A first light image from the scope of the relatively faint emission nebula IC1396 is shown below. This is a total integration of 2 hours (6 x 20 min sub-exposures) which indicates the potential of this scope for capturing extended nebula regions at great depth with speed.

Further details of the TS Photoline 60mm refractor can be found on the Telescope Service website. The specification of this scope is identical to the Stellavue SV60EDS and it provides an affordable alternative to the Takahashi FS-60CB.

IC1396 – Large emission nebula in Cepheus

IC1396v3IC 1396 is a large and comparatively faint emission nebula and star forming region over 100 light-years across in the constellation Cepheus. It is energised by the bright central triple star system called HD 206267. All three components are massive stars and the intense ultraviolet radiation they give off ionizes the gas of IC 1396 causing compression of the denser globules of the nebula leading to star formation. Among the intriguing dark shapes within IC 1396 is the dense globule of gas and dust known as the Elephant’s Trunk nebula (IC 1396A) located in the upper central part of the image. The image shows emission in the Hydrogen Alpha (Ha) line at 656nm.

This is a first light image from my new wide field imaging system based on the Telescope Service Photoline TS60ED refractor. This has a 60mm apochromatic doublet lens with a FPL53 element by Ohara (Japan). I am using the TS Photoline 4-element 2 inch 0.79x reducer to decrease the focal length from 330mm to 260mm which increases the focal ratio from F/5.5 to an impressive F/4.4 for imaging.

Right ascension: 21h 39m 55.3s | Declination: +57° 36′ 48.8″ | Distance: 2,400 Light Years
Field of view: 234 x 176 arcmin

Camera: QSI 583wsg
Optics: TS Photoline TS60ED F/4.4 APO
Guiding: Off-axis with Lodestar guider
Filters: Baader Ha (7nm)
Exposures: Ha 6 x 20 min
Total exposure: 2 hours
Image composition: Monochrome Ha
Scale: 4.2 arcsec/pixel
Image acquired: 17th July 2015

Image capture with MaxIm DL, FocusMax, ACP; Image processed with MaxIm DL and Photoshop CC 2014 [Astronomy Tools v1.6; HDR Toning]

Elephant’s Trunk Nebula in IC1396

IC1396-ST10-v3.4sThe Elephant’s Trunk nebula is a concentration of interstellar gas and dust within the larger emission nebula IC 1396 located in the constellation Cepheus about 2,400 light years away from Earth. The image shows the dense globule IC 1396A commonly known as the Elephant’s Trunk nebula because of its appearance as a sinuous dark cloud at visible light wavelengths. The bright edge of the cloud is where its surface is being illuminated and ionised by the very bright and massive nearby triple star system HD 206267A.

I acquired the image while testing the Starlight Xpress active optics unit which hopefully will enable me to increase sub-exposures to 30 minutes while operating the APM 152-1200ED telescope at its native focal length of 1,200 mm. Note that the data were acquired under astronomical twilight and first quarter / full moon in June which is a testament to narrowband imaging and Astrodon filters in particular.

Right ascension: 21h 35m 33s | Declination: +57° 25′ 52″ | Distance: 2,400 Light Years
Field of view: 42 x 28 arcmin
Camera: SBIG ST-10XME
Telescope: APM 152-1200ED F/7.9
Guiding: Starlight Xpress Active Optics SXV-LF-AO
Filters: Astrodon Ha (3nm), OIII (3nm)
Exposures: Ha 9 x 20 min, OIII 15 x 20 min
Total exposure: 8 hours
Image composition: Cannistra Modified Bicolour Narrowband Technique
Scale: 1.15 arcsec/pixel
Image acquired: June 2015

Image capture with MaxIm DL, FocusMax, ACP; Image processed with MaxIm DL; Photoshop CS4/CC