Monthly Archives: August 2012

Pickering’s Triangle and Witch’s Broom Nebula – NGC6960

This is the western portion of the Cygnus Loop – a large supernova remnant in the constellation of Cygnus. The image was acquired remotely using the iTelescope.net T16 telescope located at the AstroCamp observatory, Nerpio, SE Spain.

Right ascension: 20h 48m 02s | Declination: +30° 57′ 36″ | Distance: 1,400 Light Years
Field of view: 75.4 x 113.1 arcmin

Camera: SBIG STL-11000M
Telescope: Takahashi TOA-150 iTelescope.net T16
Filters: Astrodon Ha, OIII
Exposures: Ha 13 x 10 min; OIII 17 x 10 min
Total exposure: 4 hours
Image composition: Bi-spectral Narrowband [Ha] [OIII] [OIII 75% + Ha 25%]
Scale: 1.69 arcsec/pixel
Image acquired: 16 & 23 August 2012 from Nerpio, Spain

Image capture with MaxIm DL, FocusMax, ACP; Image processed with MaxIm DL (Fat Tail Deconvolution, DDP), Photoshop CS4

Cygnus Wall – NGC7000

The Cygnus Wall in the southern part of the North American Nebula (NGC 7000). This is an ionisation front where UV light from hot young stars is transforming the cold gas of interstellar space into a ‘wall’ of ionised hydrogen. The Hα emission line is colour mapped onto yellow, gold and brown in the image.

Right ascension: 20h 58m 50s | Declination: +43° 36′ 39″ | Distance: 1,800 Light Years
Field of view: 57 x 38 arcmin

Camera: SBIG ST-10XME
Telescope: William Optics Megrez 120 F/7.5
Guiding: Starlight Xpress Active Optics (SXV-AO-LF) unit
Filters: Baader Ha (7nm), OIII (8.5nm), SII (8nm)
Exposures: Ha 12 x 10 min; OIII 24 x 10 min; SII 24 x 10min
Total exposure: 10 hours
Image composition: Colour Mapped Narrowband Ha:SII:Ha:OIII
Scale: 1.56 arcsec/pixel
Image acquired: July & August 2012 from Bristol (UK)

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

Rosette Nebula – Ha|OIII Bicolour Composite

The Rosette Nebula processed using the Modified Bicolour technique for combining Ha and OIII images as described by Steve Cannistra – see www.starrywonders.com/bicolortechniquenew. The bicolour method creates a synthetic green channel (sG) to create a final RGB colour composite Ha:sG:OIII.

Right ascension: 06h 31m 44s | Declination: +05° 08′ 49″ | Distance: 5,000 Light Years
Field of view: 57 x 38 arcmin

Camera: SBIG ST-10XME
Telescope: William Optics Megrez 120 F/7.5
Guiding: Starlight Xpress Active Optics (SXV-AO-LF) unit
Filters: Baader Ha (7nm), OIII (8.5nm)
Exposures: Ha 26 x 15 min; OIII 48 x 15 min
Total exposure: 18.5 hours
Image composition: Modified Bicolour Ha|sG|OIII composite
Scale: 1.56 arcsec/pixel
Image acquired: January 2012 from Bristol (UK)

Image capture with MaxIm DL, FocusMax, ACP; Image processed with MaxIm DL (DDP, Fat Tail Deconvolution), Photoshop CS4.

Dust Sculptures in the Rosette Nebula

This part of the Rosette Nebula also known as NGC 2237 contains sculpted globules of dark dust and gas that are slowly being eroded away by the energetic light and winds of nearby massive stars. I am waiting for the Rosette to become visible again over the winter months to capture SII and OIII emission line data.

Right ascension: 06h 31m 44s | Declination: +05° 08′ 49″ | Distance: 5,000 Light Years
Field of view: 57 x 38 arcmin

Camera: SBIG ST-10XME
Telescope: William Optics Megrez 120 F/7.5
Guiding: Starlight Xpress Active Optics (SXV-AO-LF) unit
Filters: Baader Ha (7nm)
Exposures: Ha 26 x 15 min
Total exposure: 6.5 hours
Image composition: Monochrome Ha
Scale: 1.56 arcsec/pixel
Image acquired: January 2012 from Bristol (UK)

Image capture with MaxIm DL, FocusMax, ACP; Image processed with MaxIm DL (DDP, Fat Tail Deconvolution), Photoshop CS4.

SBIG ST-10XME with Active Optics guiding

In January 2012 I upgraded to an SBIG ST-10XME CCD camera and at the same time purchased a Starlight Xpress SXV-AO-LF active optics unit to improve guiding accuracy.

The ST-10XME has a quantum efficiency (QE) of over 85% between 560-665 nm which includes the Hα emission line at 656.3 nm. It is a no anti-blooming gate (NABG) sensor which accounts for its high QE but the negative side of this is that when a pixel saturates a bloom (or vertical streak) is produced in the resulting image. My rationale for choosing the ST-10XME was the additional sensitivity given high light pollution levels in central Bristol and my decision to operate the Megrez 120 at F/7.5 (900mm FL). I currently use the Wodaski MaxIm DL plug-in to de-bloom my images.

The SXV-AO-LF unit works very well under ACP control. ACP automates guide star selection which avoids the hot pixels in the Lodestar guider and optimises exposures to give short track times (< 0.5 seconds) and fast guide rates (≥ 4 Hz). It has transformed the performance of my EQ6 mount. I can now routinely achieve round stars (Roundness ≤ 0.05) and FWHM values ≤ 2 arc seconds under moderate to good seeing. During the galaxy season with sparse star fields I do sometimes revert to standard off-axis guiding when selecting a suitable guide star for the AO unit is sub-optimal.