Monthly Archives: February 2011

The heart of the Heart Nebula

The three bright stars are O and B type giants (20-100 times more massive than our sun) of the Melotte 15 open cluster.  Stellar winds and intense ultraviolet radiation from these massive stars has sculpted the twisted tree-like structure in the image from within the centre of the extremely large cloud of ionised hydrogen gas that makes up the Heart Nebula (IC 1805) located in the Persius spiral arm of our galaxy.

Right ascension: 02h 33m 50s | Declination: +61° 26′ 03″ | Distance: 7,500 Light Years
Field of view: 34 x 25 arcmin

Camera: Atik 314L+
Telescope: William Optics Megrez 120 F/7.5
Filters: Baader Ha (7nm), OIII (8.5nm), SII (8nm)
Exposures: Ha 28 x 10 min; OIII 44 x 10 min; SII 30 x 10 min
Total exposure: 17 hours
Image composition: LRGB (Ha, SII, Ha, OIII)
Scale: 1.48 arcsec/pixel
Image acquired: 24 & 25 Dec 2010; 8, 9, 18, 20 & 28 Jan 2011 from Bristol (UK)

Image capture and guiding with MaxIm DL; Image processed with MaxIm DL, AIP4Win, Photoshop CS4

Filaments of dust and Bok globules in the Rosette Nebula

Dark filaments of dust radiating towards the centre of the Rosette nebula (NGC 2244).  The twisted helical pattern of these filaments is thought to be moulded by the interplay of stellar winds, radiation and electromagnetic forces emanating from the central cluster of hot young stars.  This is my favourite part of the Rosette – I particularly like the way the filaments of dust take on animal-like forms.

Right ascension: 06h 31m 44s | Declination: +05° 08′ 49″ | Distance: 5,000 Light Years
Field of view: 34 x 25 arcmin

Camera: Atik 314L+
Telescope: William Optics Megrez 120 F/7.5
Filters: Baader Ha (7nm), OIII (8.5nm), SII (8nm)
Exposures: Ha 15 x 10 min; OIII and SII each 6 x 5 min binned 2×2
Total exposure: 3.5 hours
Image composition: LRGB (Ha, SII, Ha, OIII)
Scale: 1.48 arcsec/pixel
Image acquired: 16/12/10 & 24/01/11 from Bristol (UK)

Image capture and guiding with MaxIm DL; Image processed with MaxIm DL, CCDSharp, Photoshop CS4

Imaging | Guiding | Focusing

This was the setup for my imaging train during 2010-2011.

The imaging camera is the Atik 314L+.  The camera is based on the sensitive Sony ExView ICX285AL sensor with a 1392×1040 CCD array of 6.45µm pixels.  It has full set point temperature regulation (cooling to – 27°C below ambient) enabling the creation of matched dark frame sets for calibration.  Image acquisition is controlled by MaxIm DL.

I use an off-axis guider for guiding long exposures which are typically of 10-15 minutes duration.  The photograph shows the Telescope Service low profile off-axis guider with the Starlight Xpress Lodestar autoguider attached.  The Lodestar is based on the Sony ICX429AL sensor with 8.2µm x 8.4µm pixels.  It is incredibly sensitive and never fails to offer a choice of guide stars even though I often use 0.5 second exposures during guiding.  Guiding is performed under MaxIm DL control and I use pulse guiding to send autoguiding commands to the telescope.

The dual speed Crayford focuser on the Megrez 120 has been modified with a motorised focusing system from LakeSide Astro.  It comprises an ASCOM compliant control unit and a stepper motor assembly which is controlled using FocusMax linked to MaxIm DL.  Autofocusing with Focus Max is fast and extremely accurate and is the key to obtaining sharp and detailed high-resolution images.

Elephant’s Trunk Nebula – IC1396A

The Elephant’s Trunk nebula is a dark and dense globule of interstellar gas and dust in the star cluster IC 1396 – an ionised gas region located in the constellation Cepheus about 2,400 light years away from Earth.

Right ascension: 21h 34m 38s | Declination: +57° 26′ 325″ | Distance: 2,400 Light Years
Field of view: 38.1 x 28.5 arcmin

Camera: Atik 314L+
Telescope: GSO 200 8” F/4 Newtonian Astrograph
Guiding: Telescope Service OAG with Starlight Xpress Lodestar guider
Filters: Baader Ha (7nm), OIII (8.5nm), SII (8nm)
Exposures: Ha 30 x 6 min; OIII 21x 6 min; SII 10 x 6min
Total exposure: 6 hours
Image composition: Colour Mapped Narrowband Ha:SII:Ha:OIII
Scale: 1.64 arcsec/pixel
Image acquired: July & August 2010 from Bristol (UK)

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

William Optics Megrez 120 APO F/7.5

This is my primary telescope – a William Optics Megrez 120mm F/7.5 APO refractor. It uses a very high quality Japanese Ohara FPL-53 fluorite glass doublet lens with excellent colour correction. This is the latest version with an upgraded focuser steel base plate for improved performance under heavy load. It is mounted on a Skywatcher EQ6 mount under EQMOD / ACP control.

I choose to operate the telescope at its native focal length of 900 mm which gives me an image plate scale of 1.5 arcseconds with my Atik 314L+ and SBIG ST10-XME CCD cameras.