Veil Of Darkness

June 10, 2022 by grahamrob in Broadband, Dark Nebula, Deep Sky Objects, Imaging, Widefield Imaging and tagged Milky Way, Pleiades, Taurus Constellation | Leave a comment

Just northeast of the Pleiades star cluster within the northern Milky Way, lies the dark region of the Taurus Molecular Cloud (TMC), which at 430 light years is the nearest star-forming region to Earth. Consisting of hundreds of solar masses of primordial hydrogen and helium gas, as well as heavier elements, this vast area of dense stardust obscures almost all light from behind. As such it forms an alluring target for astrophotography, with the complex rift-like dark structure of the TMC set against the broad starry background of the Taurus constellation.

Notwithstanding, perhaps because of the more popular objects that abound throughout its neighbour the Orion constellation, the TMC is somewhat neglected by astronomers; to be fair the TMC is also a more challenging imaging target than many of those found in Orion. Early this year, for the first time I decided to image the dark nebula Barnard 22, an iconic section of the TMC formed by a complex mass of dark stardust that appears to hang within the vast surrounding starfield.

Approaching the new moon in late January I obtained almost 11 hours of LRGB subs, though sadly was unable to incorporate another 6-hours of 10-minute luminance exposures which proved to be too bright to use: note-to-self – check settings for new objects before embarking on long imaging programme! To achieve a balance between the large black smudge that is B 22 and the brilliance of the surrounding stars processing was tricky but the final outcome satisfying. Also noteworthy in the image, just off centre is the small flame-shaped reflection nebula IC 2087, the light from which just manages to emerge from behind the otherwise dominant, though beguiling form of Barnard 22, which like night itself seems to casts a dark veil over the cosmos.

	IMAGING DETAILS
Objects	Barnard 22 dark nebula & IC 2087 reflection nebula
Constellation	Taurus
Distance	Approx.. 430 light years
Size	–
Apparent Magnitude	Varies

Scope	William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount	SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding	William Optics 50mm guide scope
	+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera	ZWO1600MM-Cool mono CMOS sensor
	FOV 2.65^o x 2.0^o Resolution 2.05”/pix Max. image size 4,656 x 3,520 pix
EFW	ZWOx8 EFW & 31mm Chroma LRGB filters
Capture & Processing	Astro Photography Tool + PHD2 + Deep Sky Stacker, PixInsight v1.8.8-12, Photoshop CC, Topaz AI DeNoise
Image Location & Orientation	Centre RA 04:39:00.365 DEC +26:00:13.426 Lower Left = North
Exposures	120 x 180 sec L, 19 x 300 sec R, 20 x 300 sec G & B Total Integration Time: 10hr 55 min
	@ 139 Gain 21 Offset @ -20^oC
Calibration	10 x 60 sec Darks 15 x LRGB Flats & Dark Flats @ ADU 25,000
Location & Darkness	Fairvale Observatory – Redhill – Surrey – UK Typically Bortle 5-6
Date & Time	27^th 29^th 31^st January + 4^th & 6^th February 2022 @ +18.30h
Weather	Approx. <4^oC RH >=75% 🌙 around New Moon

Reach For The Stars

December 21, 2021 by grahamrob in Broadband, Deep Sky Objects, Imaging, Software, Star Cluster and tagged M45, Orion Constellation, Pleiades, Taurus Constellation | Leave a comment

Preceding the arrival of what is for many astronomers the highlight of the year, the Orion constellation and all it’s objects, is the appearance of the majestic Pleiades open star cluster (Messier 45) in the constellation of Taurus. The so-called Seven Sisters consists of hot blue luminous stars that formed during the past 100 million years, which are expected to last another 250 million years and can be easily observed with the naked eye even here at Fairvale Observatory (Bortle 5/6).

I have imaged this exciting star cluster before but with astrophotography and especially iconic objects such as the Pleiades, one is always drawn back for another try. Now armed with Chroma filters and a growing list of PixInsight skills acquired since last imaged late in 2018, I wanted to tease out more details of the fine wispy dust cloud through which the Sisters are passing and forms the signature of all good Pleiades’ images. Furthermore, with longer exposures and total integration time greater than before, maybe I could also capture something of the abundant interstellar dust that is present across the wider background?

I am therefore very pleased that the final image (top of the page + cropped version above) which has more than achieved these objectives and marks a significant improvement on my previous attempts – it’s always worth trying that little bit more.

	IMAGING DETAILS
Object	M45 The Pleiades AKA Seven Sisters
Constellation	Taurus
Distance	444 light-years
Size	110’
Apparent Magnitude	+1.6

Scope	William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount	SW AZ-EQ6 GT + EQASCOM computer control
Guiding	William Optics 50mm guide scope
	+ Starlight Xpress Lodestar X2 guide camera & PHD2 control
Camera	ZWO1600MM-Cool (mono) CMOS sensor
	FOV 2.65^o x 2.0^o Resolution 2.05”/pix Max. image size 4,656 x 3,520 pix
EFW	ZWO x8 EFW & Chroma 31mm LRGB filters
Capture & Processing	Astro Photography Tool + Deep Sky Stacker PixInsight v 1.8.8-11, Photoshop CS3, Topaz AI Denoise
Image Location & Orientation	Centre: RA 03:47:03 DEC 24:03:08 Top = North Right = West
Exposures	12 x 300 sec LRGB Total time: 4 hours
	@ 139 Gain 21 Offset @ -20^oC
Calibration	5 x 300 sec Darks 15 x Flats & Dark Flats LRGB @ ADU 25,000
Location & Darkness	Fairvale Observatory – Redhill – Surrey – UK Typically Bortle 5
Date & Time	6^th December 2021 @ +19.15h
Weather & Moon	Approx. <=4^oC RH >=85% 🌙 New Moon

Nice But Dim

March 31, 2020 by grahamrob in Deep Sky Objects, History, Imaging, Nebula and tagged Gemini, Milky Way, Pleiades | 1 Comment

Abell 21 Combo All 2018 2020 RGB FINAL CROP (Large)

Contrary to appearance, a planetary nebula is not a planet but a emission nebula, an expanding shell of glowing ionized gas discharged from a red giant star at the end of its life. At this late stage of stellar evolution the star runs out of fuel to burn, with the result that the outer layers are blown away and expand into space typically in the shape of a ring or bubble. At the centre of the planetary nebula is the remnant of the star, which is left as a White Dwarf.

JEL_ITV_ElementFormation_BG-Plate_Updated_23Oct17

The term “planetary” nebula is therefore completely misleading and derives its name from none other than William Herschel, in an era when such objects were thought to look like planets. We now believe some 10,000 planetary nebulae exist throughout the Milky Way, though only 1,500 have been identified (see NASA HST images below), including M57 the Ring Nebula and M27 the Dumbbell Nebula both popular amongst astrophotographers.

HST PN Such objects are usually short lived and unfortunately small and faint, making them a challenge for smaller telescopes and Bortle 5-6 skies, such as I have at Fairvale Observatory. However, I recently decided to return to the Medusa Nebula, a planetary nebula which I previously had imaged as a test in February 2018. On that occasion the integration time was limited to only 75 minutes (see below), now the objective was to build on the previous data and thereby hopefully improve the image quality.

Abell 21 RGB 2018 Final (Large)

Combining the data from 2018 with that of 2020 resulted in a significant increase in total integration time to just over 5-hours, with the impact on the final image clearly noticeable (see top-of-the-page cropped and below uncropped – showing the difference in alignment between pre-plate solving 2018 & 2020 data), mainly in the form of reduced noise and better colour saturation. I am a little surprised that the improvement was not greater but perhaps it’s a case of either (a) considerably more time is still required, particularly in the weak OIII wavelength, or (b) it’s really too much of a challenge for my equipment?

Ha wavelength

OIII wavelength

However, looking at other images of the Medusa Nebula and considering its size and very low surface brightness, it’s obvious this is one of the more difficult planetary nebula objects to image and all things considered I’m happy with outcome new of this new version.

Abell 21 Combo All 2018 2020 RGB FINAL

	IMAGING DETAILS
Object	The Medusa Nebula AKA Abell-21, Sharpless 2-274 or PK205+14.1
Constellation	Gemini
Distance	1,500 light-years
Size	Approx.. 12’ x 9’
Apparent Magnitude	+15.99

Scope	William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount	SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding	William Optics 50mm guide scope
	+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera	ZWO1600MM-Cool mono CMOS sensor
	FOV 2.65^o x 2.0^o Resolution 2.05”/pix Max. image size 4,656 x 3,520 px
EFW	ZWOx8 + ZWO LRGB & Ha OIII SII 7nm filters
Capture & Processing	Astro Photography Tool + PHD2 + Deep Sky Stacker & Photoshop CS3
Image Location & Orientation	Centre RA 05:55:38 DEC 01:59:40 @20.49h Image rotated 180^o for presentation Top = South
Exposures	37 x 300 sec Ha, 25 x 300 sec RGB Total Time 5hr 10 min
	@ 139 Gain 21 Offset @ -20^oC
Calibration	5 x 300 sec Darks 20 x 1/4000 sec Bias 10 x Ha & OIII Flats @ ADU 25,000
Location & Darkness	Fairvale Observatory – Redhill – Surrey – UK Typically Bortle 5-6
Date & Time	11^th February 2018 + 2^nd & 3^rd March 2020 @ +21.00h
Weather	Approx. 5^oC RH <=75% 🌙 +29% waxing

Vanguard Of The Winter Night Sky

December 5, 2018 by grahamrob in Deep Sky Objects and tagged Pleiades, Star Clusters, Taurus | Leave a comment

Each year whilst the Earth rotates around the Sun, we are also moving through the Milky Way and the Universe itself. In time, measured by millions of years, the pattern of the night sky will change but for now, measured on a human scale it appears fixed and as a result has become very familiar, so much so that it has formed the basis of navigation for millennia. For astronomers this affect also results in a predictable pattern of changes during the year, so that every 12-months we first anticipate and then revisit old ‘friends’, none more so than the winter night sky which contains some of the most exciting objects of the year.

Surprisingly it is possible to obtain an early glimpse of these objects just before dusk at the end of a night’s viewing in the late summer but the real show begins during November, when they start to appear more conveniently in the darkness of the early evening. With this in mind I recently set out to image the vanguard of the winter night sky, Messsier 45 or the Pleiades, an open cluster dominated by bright blue stars. Located at the ‘front’ of the Taurus constellation, this group of stars heralds the arrival of Orion, perhaps the most spectacular and certainly most imaged constellation of the year, followed by Monoceros, Gemini and Auriga with their own wonderful deep sky objects – but first Pleiades.

The Pleiades star cluster is visible from almost every part of the globe, from the North Pole to beyond the southernmost tip of South America. The cluster consists of over 1,000 young stars, although only 14 can be seen with the naked eye, of which seven make up the Pleiades asterism or so-called Seven Sisters. The Sisters can usually be seen in light polluted skies but in a dark sky, such as I recently experienced at the Les Granges Observatory in southern France, they form a very distinct group of brilliant stars that literally seem to pierce the blackness of the night sky (top-centre image below).

I have successfully imaged the Pleiades before with a DSLR camera but this was the first serious attempt to capture their elusive charm with a more sensitive mono camera. When imaging the Sisters the objectives are two-fold – to capture: (i) their brilliance and colour, and (ii) the delicate interplay of their light illuminating the interstellar gas and dust behind which they are currently moving. It is this latter effect that forms their characteristic signature which differentiates them from other open star clusters.

Given the brightness of the Pleiades stars I chose short 60-second LRGB exposures at Unity setting. Such is the subtle nature of the interstellar illumination against the intensity of the large, bright Pleiades stars, that post-processing needs to be especially careful in order to tease out the contrasting nature of the two features. The result is a beautiful image (top-of-the-page) that captures the power and beauty of this special group of stars which precedes Orion later in the evening at this time of the year and which with luck, will once again provide further exciting opportunities as we continue to move through the rich period of the winter night sky of which the appearance of Pleiades foretells.

	IMAGING DETAILS
Object	M45 Pleiades
Constellation	Taurus
Distance	444 light-years
Size	110’
Apparent Magnitude	+1.6

Scope	William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount	SW AZ-EQ6 GT + EQASCOM computer control
Guiding	William Optics 50mm guide scope
	+ Starlight Xpress Lodestar X2 guide camera & PHD2 control
Camera	ZWO1600MM-Cool (mono) CMOS sensor
	FOV 2.65^o x 2.0^o Resolution 2.05”/pix Max. image size 4,656 x 3,520 pix
EFW	ZWOx8 + ZWO LRGB & Ha OIII SII 7nm filters
Capture & Processing	Astro Photography Tool + PS2, Deep Sky Stacker & Photoshop CS2, HLVG
Image Location & Orientation	Centre RA 03:47:06 DEC 24:13:04 Top = North West
Exposures	50 x 60 sec L & 45 x 60 sec RGB (Total time: 185 minutes)
	@ 139 Gain 21 Offset @ -20^oC
Calibration	15 x 60 sec Darks 20 x 1/4000 sec Bias 10 x Flats LRGB @ ADU 25,000
Location & Darkness	Fairvale Observatory – Redhill – Surrey – UK Typically Bortle 5
Date & Time	17^th November 2018 @ +21.30h
Weather & Moon	Approx. 6^oC RH <=80% 🌙 Half Waxing Gibbous

It’s All Relative

December 6, 2016 by grahamrob in Deep Sky Objects, General Astronomy, Imaging, Processing, Software, Universe and tagged DSO Imaging, Einstein, Monoceros, Orion, Perseus, Pleiades | 2 Comments

escher

I spent the first half of this year reading Walter Isaacson’s biography of Albert Einstein, which apart from providing a fascinating insight into the man and his work, whetted my appetite to understand better the science. Following previous success studying astronomy courses online, I set out to find a suitable programme to achieve this goal. As a result I enrolled for Understanding Einstein: the Special Theory of Relativity run by Professor Larry Lagerstrom of Stanford University, USA, which after two months I have just completed. spacetime

The course is a good mix of qualitative and quantitative information, which at times has been quite challenging but nonetheless proved very worthwhile. The lecturer is very clear and thorough, an essential quality when dealing with this difficult and often bewildering subject. Einstein’s paper On the Electrodynamics of Moving Bodies outlines the Special Theory and was just one of four published at about the same time in 1905 (“The Miracle Year”) which included: Brownian motion, Mass-energy equivalence (E=Mc²) and The Photoelectric Effect, the latter of which won him the Noble Prize. At the end I now feel I understand the basics of Einstein’s ground breaking science properly, which apart from being interesting provides valuable insight and understanding of the Universe and related issues of space and time.

300px-world_line-svg

During this period I have also been thinking about how to improve my astrophotography and the way forwards. I’ll be on the learning curve for years to come and accept that there’s much I can still improve on using current equipment and processes but after more than 2-years astroimaging, mostly with a DSLR camera, I feel I have reached something of a crossroads and need to change tack in order to achieve more meaningful advances once again. Inevitably this is likely to mean new equipment and most likely a move to LRGB / Narrowband format. In the interim, whilst I consider the options, I have also been researching suitable capture / sequencing software, post-processing techniques and programmes. I am concerned that this will result in another level of complexity but I think it has to be done in order to progress – watch this space.

Continuing a trend that’s been apparent for the past year, clear nights have been something of a rarity since mid-September; this is a concern if I am to pursue astrophotography to the next level. However, high pressure was unusually dominant over Fairvale Observatory during the last days of November and cold, clear skies have provided good conditions for astronomy at last.

Getting better – PHD2 screen 30th November 2016: DEC is good but room for improvement with the RA settings. The impact on tracking and image quality is noticeable.

Whilst I have certainly not fully mastered guiding I am now routinely using PHD2. This in itself has probably been the major breakthrough this year, which with the aforementioned clear skies I wanted to take full advantage of. Hidden within PHD2 I have also discovered and am now starting to experiment with the on-screen drift align routine, with reasonable results; using the gamepad for mount control and a new wireless link with my tablet computer, I can also make focus and alignment adjustments at the mount without returning to the computer each time.

As a result I have dispersed with the SynScan handset for alignment and can now completely set-up and control imaging with the computer and tablet; this is nothing short of a revolution which I am hopeful will greatly increase set-up time as well as improving control and tracking accuracy – yipee! Even with average guiding results I am now achieving good exposures of 5-minutes or more and therefore decided to put this success to work and re-image some winter wonders over three, yes three, consecutive nights at the end of November.

Imaging targets between 28th & 30th of November 2016 – for descriptions & previous images taken of these objects click on the following list of names: (1) M45 Pleiades (2) Barnard 33 The Horsehead Nebula & NGC 2024 Flame Nebula (3) M42 Orion Nebula (4) NGC 2244 Rosette Nebula (5) NGC 1499 California Nebula (6) IC 405 Flaming Star Nebula

The night sky at this time of the year contains many of my favourite objects, but surprisingly I had not imaged some of the chosen targets for more than a year or two and it was both enjoyable and pleasing to reacquaint myself again. With a new perspective gained from this exercise, the progress I have made with equipment and techniques is more apparent. Notwithstanding, it’s time to move on – everything’s relative.

M45 Pleiades, Taurus constellation: 12 x 300 sec @ ISO 800 | 28th November 2016

NGC 2014 Flame Nebula & Barnard 33 Horsehead Nebula, Orion constellation: 15 x 300 sec @ ISO 800 | 28th November 2016

M42 Orion Nebula & M43 De Mairan’s Nebula, Orion constellation: 2 x 300 sec @ ISO 800 | 28th November 2016

NGC 2244 Rosette Nebula, Perseus arm of Milky Way, Monoceros region: 21 x 300 sec @ ISO 800 | 29th November 2016

California Nebula, Perseus constellation: 12 x 300 sec @ ISO 800 | 30th November 2016

IC 405 & 410 nebulae: 15 x 300 @ ISO 800 | 30th November 2016

Notes: all images taken using a William Optics GT81 refractor telescope + PHD2 guiding + modded Canon 550D DSLR & x0.80 field flattner @ ISO 800 with full darks + bias + flats calibration and processed in Deep Sky Stacker & Photoshop CS2

Spring Skies

April 12, 2015 by grahamrob in Deep Sky Objects, Imaging, Solar system, Widefield Imaging and tagged Pleiades, Taurus, Venus | Leave a comment

It’s three weeks since the Spring Equinox and two weeks since moving to British Summer Time (BST or daylight saving, GMT+1 hour), the result is that the night sky starts much later in the evening and is rapidly decreasing in length; it is just about six weeks before Astronomical Darkness completely ceases and will not come back until the end of July. In addition, through a combination of European pollution and fine sand from the Sahara drifting over South East England this week, otherwise clear skies were badly obscured by the resulting haze. As a result, since shortly before the full Moon on April 4^th astronomy has not been possible – until last night.

The march of time and annual movements of the Solar System inevitably lead to a significant loss of quantity and quality of darkness at this time of the year.

Taken this morning, the contrails over Fairvale Observatory make a striking picture but together with other pollution are having a significant impact on seeing conditions here at the moment.

In the early evening twilight sky for a brief period between sunset and astronomical darkness, at the moment Venus is low on the western horizon. Last night its apparent position was also close to the Pleiades star cluster, making an attractive widefield photograph. Furthermore, shortly before Venus moved below the horizon and the sky had nearly reached Civil Darkness, the constellation Taurus also became visible to the south west with the bull’s ‘eye’ star Alderbaran and the v-shaped Hyades star cluster clearly evident.

Venus at sunset last night: the Pleiades can only just be seen at 2-o’clock to Venus with Taurus on the far left.

Twenty minutes after sunset shortly before reaching Civil Darkness, the Pleiades and Taurus constellation are now quite clear.

Such a picture is a reminder that it is important to consider photography other than telescopic based planetary and deep sky imaging, especially as viewing and imaging conditions become more limited over the forthcoming Summer period.