Galactic Stepping Stones

April 20, 2021 by grahamrob in Broadband, Deep Sky Objects, Galaxy, General Astronomy and tagged Coma Berenices, Filters, Virgo | Leave a comment

The Virgo Cluster consists of more than 2,000 galaxies, which unfortunately are optically too much for my small William Optics GT81 telescope individually. However, one of several sub-groups within the Virgo Cluster forms a striking J-curve shape that does make for a pleasing LRGB image. Discovered and named after the Armenian astrophysicist Benjamin Markarian, Markarian’s Chain is a string of bright galaxies that share a common motion through space. I first imaged the Chain in April 2015 using a modded DSLR and then again in April 2017, as my first LRGB image with the then new ZWO ASI1600MM-Cool camera but with integration times of less than 1-hour on both occasions, the resulting images were far from ideal. On this occasion using my new Chroma LRGB filters for the first time I was determined to do better.

The new filters and nearly 7-hours integration time has resulted in a much more dynamic and detailed image, which I believe now does justice to this spectacular group of galaxies. Analysis of the image using Astrometry.net shows just how crowded this area of Virgo is with galaxies (see annotated image above) but it is Markarian’s Chain that inevitably stands out together with a few other adjacent galaxies.

Large 10^th magnitude M84 & M86 galaxies at the western end of the Chain dominate the image. M84 is the object with the highest blue shift in the Messier catalogue, which is a result of its rapid movement (244km/sec) towards the centre of the Virgo Cluster and us. At the centre of M84 is a 1.5 billion solar mass black hole.
NGC 4420 & NGC 4388 – by comparison these edge-on galaxies together with even smaller NGC 4413 & NGC 4425 seem to frame the larger M84 and M86.
Next along the Chain is a pair of interacting galaxies, the smaller round shaped NGC 4435 and NGC 4438 with its distorted disk, known as “The Eyes”.
As the Chain starts to turn, some 20’ along is NGC 4458 and its partner, the 11th magnitude elliptical NGC 4461.
The final section of the Chain consists first of NGC 4473, its brightness generated by a supermassive black hole – at 100 million solar masses its diameter of 4.46au which would stretch from the Sun to the asteroid belt! Thereafter the 11.4 magnitude barred lenticular galaxy NGC 4477 defines the north eastern extremity of Markarian’s Chain.
As previously noted, there are many other galaxies in this part of the Virgo Cluster. Perhaps most notable though is M87, from which the first ever image of a black hole was the obtained in 2019 – consisting of some 6.5 billion solar masses.

All-in-all Markarian’s Chain makes for a rewarding image using my small telescope combined with the new Chroma filters. Such is the nature of the image the galaxies might also suggest a string of pearls or perhaps galactic stepping stones – metaphorically leading to the next phase of my astroimaging journey.

	IMAGING DETAILS
Object	Markarian’s Chain
Constellation	Virgo & Coma Berenices
Distance	50 – 55 million light-years
Size	~2.5^o total
Apparent Magnitude	Varies +10 to +12 approx.

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 v1.8.8-7, Photoshop CS3, Topaz Denoise
Image Location & Orientation	Centre RA 12:27:46.65 DEC +13:03:06.44 @21.30h Left = North
Exposures	100 x 60 sec L , 54 x 60 sec R, 55 x 60 sec G&B Total Integration Time: 6hr 44 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	5^th & 6^th April 2021 @ +21.00h
Weather	Approx. <2^oC RH >=45% 🌙 30% waning

Chapeau!

May 29, 2018 by grahamrob in Broadband, Deep Sky Objects, Galaxy, General Astronomy and tagged Virgo | Leave a comment

LRGB GxC Crop-2 (Large)

I always had a general interest in astronomy but was eventually sparked into action after viewing Saturn through the Thompson 26 inch refractor at Herstmonceaux observatory in 2014. The beauty of the planet and its unique rings is captivating and like many others it remains my favourite planet to this day. One year on and looking further afield at Joan Genebriera’s Tacande Observatory on the island of La Palma, I discovered what is now one of my very favourite Deep Sky Objects – M104 or the Sombrero Galaxy; until recently I used the resulting picture obtained whilst at La Palma as the main banner image for this website. Though perhaps not as spectacular as the Orion Nebula or certain spiral galaxies, the sombrero-like galaxy (with a passing resemblance of a flying saucer too), is beguiling in its own unique way and ever since then I’ve been eager to return to The Hat and image it myself from home.

Chart_1.cdc3

However, imaging the Sombrero from the UK and especially at my location just south of London is quite another matter to La Palma. Aside from light pollution, being at 51^o north compared to 28^o in La Palma, M104 is considerably lower in the sky when viewed from Fairvale Observatory in Redhill; at the time of imaging in early May it was about 26^o above the southern horizon. Furthermore, my sight lines are obscured on three sides by 15-foot hedges and directly south by two 45-foot conifers – see below SE to SW view of M104 imaging track at Fairvale Observatory.

M104 Track crop

As a result, only after it emerges from behind the western edge of the aforesaid conifers can M104 (just) be imaged, as it moves along the top of the hedge for just over an hour before disappearing from view once again. Of course this is far from ideal but with my enthusiasm for the Sombrero, a high-resolution ZWO1600M-Cool camera and newly acquired ability to plate solve, I gave it a try over three consecutive nights.

RGB GxC crop (Large)

An unbarred spiral galaxy, the hallmark of M104 is its bright bulbous centre encircled by dark dust lanes, which when viewed from Earth tilted at just 6-degrees above the equatorial plane creates the appearance of a sombrero hat (see cropped image above). With the much higher resolution of the Hubble telescope some 2,000 globular clusters have been identified with M104, ten-times that of the Milky Way. In 1912 the galaxy was found to be moving away from Earth at 700 miles per second, providing an early indication that the Universe was in fact expanding in all directions.

All-in-all the Sombrero galaxy is a fascinating and unusual object, though small and all-in-all a challenging imaging target, especially seen from Fairvale Observatory. Notwithstanding, at last I am very pleased to obtain my own exciting image of the Sombrero – chapeau!

M104 Location

	IMAGING DETAILS
Object	Sombrero Galaxy M104
Constellation	Virgo
Distance	29 million light-years
Size	9’ x 4’ or 50,000 light-years
Apparent Magnitude	+8.0

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
Image Position	Centre RA 12:39:59 DEC -11:37:20
Exposures	25 x 180 sec L + 3x5x180 sec RGB (Total time: 120 minutes)
	@ 139 Gain 21 Offset @ -20^oC
Calibration	10 x 180sec 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	5^h + 6^th + 7^th May 2018 @ 23.30h approx.

Spring’s Playground

May 12, 2015 by grahamrob in Deep Sky Objects and tagged Coma Berenices, Galaxies, Leo, Virgo | 1 Comment

The night sky has been full of surprises for me this Spring, in particular the very extensive presence of galaxies. Their occurrence has been mostly associated with the constellations of Leo and Virgo but also less well known (to me) Coma Berenices, located between the two aforementioned constellations. Despite being the 42^nd constellation by size and relatively small with few bright stars, Coma Berenices is nonetheless something of a little gem and every bit as interesting as it’s more famous neighbours.

Previously part of the Leo Constellation, Coma Berenices was promoted to a constellation in the 16^th Century and named after Queen Berenice II of Egypt; the asterism was previously considered to be the tuft of hair at the end of the lion’s (Leo) tail, which has now become the ‘Queens Hair’. Though small, Coma Berenices contains eight Messier objects, several globular clusters and is rich in galaxies – including the northern part of the Virgo cluster – also with the North Galactic Pole located within its boundaries. All-in-all the constellation forms an impressive and interesting part of the sky at this time of the year.

Notable objects are: M53 (NGC 5024), M85 (NGC 4382), M88 (NGC 4501), M91 (NGC 4548), M98 (NGC 4192), M99 (NGC 4254), and M100 (NGC 4321). Whilst amongst the more famous features of the Coma Berenices is the Black Eye Galaxy (M64), the Needle Galaxy (NGC 4565) and the Coma Cluster of galaxies.

M64, AKA Black Eye Galaxy, Evil Eye Galaxy or the Sleeping Beauty Galaxy is the brightest in Coma Berenices and gets its name from the dark (black) dust band that obscures the stars in its bright core.

M64 Black Eye Galaxy
WO GT81 & Canon 550D (modded) + FF | 10 x 180 secs @ ISO 1,600 | 11th April 2015

NGC 4565 or the Needle Eye Galaxy is considered one of the finest examples of an edge-on galaxy, thus producing a slender, needle-like profile. Located 40 million light years away, almost directly above the North Galactic Pol, this giant barred spiral galaxy is about one third larger than the Milky Way and is more luminous that Andromeda.

NGC 4565 Needle Eye Galaxy
WO GT81 & Canon 550D (modded) + FF | 10 x 180 secs @ ISO 1,600 | 11th April 2015

Some 60 million light-years away, M88 is located in the lower area of Coma Berenices, is over 100,000 light years diameter and one of the brightest galaxies of the Virgo Cluster.

M88 with other galaxies of the Virgo Cluster nearby.
WO GT81 + Canon 550D (modded) + FF | 20 x 180 secs @ ISO 1,600 | 25th March 2015

Apart from a few occasional opportunities since obtaining my new equipment last Summer, I have been yearning for more galaxies to image and have thoroughly enjoyed Spring’s veritable playground of galaxies that have filled the sky in their hundreds and sometimes thousands since February. Notwithstanding, my 81mm refractor though good struggles to obtain the detail of these magnificent, mind-blowing Deep Sky Objects and I can only look forward to the day of owning a larger aperture telescope and have mastered the art of long-exposure tracking, which I am still working on. In the meantime, I now await the development of the Summer sky and another crack at objects first encountered last year.

All in a spin

April 23, 2015 by grahamrob in Deep Sky Objects and tagged Coma Berenices, DSO Imaging, Galaxies, Star Clusters, Virgo | 1 Comment

It is now just over six months since acquiring my new astronomy equipment and therefore the first time I have experienced imaging DSO objects of the Spring night sky. Following the passage of Leo, the main show has now well and truly arrived as the constellations of first Coma Berenices and then Virgo pass overhead, bringing with them a virtual fireworks type display of spectacular stellar features. To DSO fans Spring means one thing – galaxies – too many to comprehend, making it difficult to know where to start. In my case the detailed beauty of these galaxies will need to wait until I have a substantially larger telescope and can achieve much, much longer exposures. In the meantime I just marvel at the spectacle and have been trying to image some of the more iconic of these springtime beauties. Both constellations seem abound with galaxies but two groups are particularly exciting: the Coma Cluster and Virgo Cluster, within which there a large number of fine examples to choose from.

Just the tip of the iceberg: part of the Virgo Cluster that is crowded by galaxies.

Just the tip of the iceberg: part of the Virgo Cluster crowded with thousands of galaxies.

I was first drawn to Markarain’s Chain in the Virgo Cluster, a string of galaxies that form a gentle curve. Stretched over some x ly the chain includes two Messier Objects – M86 & M84, together with NGC 4438, NGC 4435, NGC 4461, NGC 4458, NGC 4473 & NGC 4477 amongst many others. In fact this entire part of the sky contains literally thousands of galaxies, of which Markarain’s Chain is just a small but interesting part.