Hercules | WATCH THIS SPACE(MAN)

About this time of the year as astronomical darkness is lost for a few months I tend to take it easy, astronomically speaking. However, this year’s an exception as I have a large backlog of image processing to complete courtesy of the Photon Factory. With continuously bad weather prevailing across Europe back in February, it was more than four months since I’d been able to undertake any astrophotography here at Fairvale Observatory – of course such problems go with the hobby but this was ridiculous and somewhat disheartening. There were three solutions to the situation: continue waiting, give up all together or look further afield where the skies are reliably clear and dark, which like many others nowadays is what I did and thus joined the ever increasing band of remote imagers.

About 2-years ago I considered establishing equipment at one of the growing number of astrophotography host sites in southern Europe. However, after some research I concluded that whilst such a facility would be great to have it was probably too expensive for now and moreover, I first needed to spend more time improving my processing techniques before embarking on such a plan. Thus having since taken steps towards this goal, which included learning PixInsight, I felt the time was right to sign-up with Deep Sky West (DSW) situated in the state of New Mexico, USA. DSW were one of the early remote hosting observatories established and have a good reputation, reasonable prices and a wide choice of quality equipment. I therefore signed up for one year’s imaging with the following set-up:

Takahashi FSQ 106 FL 530mm f/5 + Moonlight Nightcrawler focuser
QSI1683-WSGA camera 5.4 nm pixels & Astrodon 5nm filters
Paramount MyT mount

Deep Sky West is located about 35-miles south east of Santa Fe, at an elevation of 7,400ft on the Glorietta Mesa (see above map). Established by Lloyd Smith and Bruce Wright in 2015, there are now two large bespoke roll-off sheds (Alpha & Beta – see picture below) housing up to nearly forty rigs which are used by astrophotographers from across the world – you could call it a photon factory. DSW has since established a premier reputation as an observatory producing high quality data. Building on this success and the burgeoning demand for remote imaging, DSW are now expanding their service into Chile.

After imaging the globular cluster M53 from Fairvale Observatory in early April, it was opportune to be able to continue the same theme with my first two DSW images taken during Q1 and Q2 – the globular clusters M13 and M92, both located in the constellation of Hercules. With an angular separation of just 9^o 33’, spatially the two clusters appear as neighbours but in reality M13 is some 4,560 thousand light-years closer. Spanning some 145 light years in diameter, M13 consists of several hundred thousand stars and as the brightest globular cluster in our galaxy it is generally considered to be the finest in the Northern Hemisphere. Whilst somewhat overshadowed by its more famous neighbour, M92 is still one of the brightest globular clusters orbiting the Milky Way and at +11 billion years is one of the oldest.

Since moving to mono imaging in 2017 I’ve only used a CMOS camera and therefore this is my first experience of working with CCD data, hitherto considered as the best, though more recent development of CMOS sensors suggests this is now likely to be the way forwards for amateur astrophotography. Whilst most of the techniques are the same there are minor differences such as using bias frames instead of dark flats with my CMOS camera for calibration.

The DSW equipment combination produces a field-of-view nearly 50% less than my equipment at home but with a similar resolution, thus improving the magnification and image details of smaller and/or complex features such as globular clusters. Notwithstanding, I was pleased with my previous image of M13 (above) taken from Fairvale Observatory in 2018, which after cropping compares well with the new DSW version (see main image at the top of the page). This is my first image of M92 (below), which though OK probably needs more attention, as I’m not convinced the combination of the 600 secs + 300 secs + 60 secs data has worked to its full potential.

The Takahashi 106 is one of my dream scopes and with up to 250 clear nights a year historically, the DSW location in New Mexico provides an opportunity to work with top level equipment in outstanding night sky conditions – what’s not to like with remote imaging? However, with a growing cadre of remote imagers this has become a something of a contentious issue amongst astrophotographers – there’s no doubt it produces excellent data which leads to outstanding images but as a hobby it’s still good to be hands-on. So far I’m really enjoying working with the remote data produced under optimum conditions but strangely there’s much to be said for imaging in the backyard even with or perhaps because of the problems it involves. Funny old world!

	IMAGING DETAILS
Object	M13 The Great Globular Cluster in Hercules
Constellation	Hercules
Distance	22,180 light-years
Size	20.0 arc minutes
Apparent Magnitude	+5.8

Scope	Takahashi FSQ 106 FL 530mm f/5 + Moonlight Nightcrawler focuser
Mount	Paramount MyT
Guiding	Yes
Camera	QSI 683-WSG8 with KAF-8300 full frame CCD sensor and 5.4nm pixels
	FOV 1.94^o x 1.46^o Resolution 2.1”/pix. Image array 3326 x 2,507 pix
Processing	Deep Sky Stacker, PixInsight v1.8.8-7, Photoshop CS3, Topaz Denoise
Image Location	Centre – RA 16:41:41.701 DEC +36:27:34.927
Exposures	49 L 34R 36G 36 B x 300 secs @ -15C Total Integration Time: 12hr 55min
Calibration	48 x 900 secs Darks* x47 Bias & x20 LRGB Flats *scaled to 300sec
Location & Darkness	Deep Sky West – amateur hosting facility near Rowe, New Mexico, USA SQM Typically >= 21.7
Date & Time	Q1 2021

	IMAGING DETAILS
Object	M92 Globular Cluster
Constellation	Hercules
Distance	26,740 light-years
Size	14.00 arc minutes
Apparent Magnitude	+6.3

Scope	Takahashi FSQ 106 FL 530mm f/5 + Moonlight Nightcrawler focuser
Mount	Paramount MyT
Guiding	Yes
Camera	QSI 683-WSG8 with KAF-8300 full frame CCD sensor and 5.4nm pixels
	FOV 1.94^o x 1.46^o Resolution 2.1”/pix. Image array 3326 x 2,507 pix
Processing	Deep Sky Stacker, PixInsight v1.8.8-7, Photoshop CS3, Topaz Denoise
Image Location	Centre – RA 17:17:07.165 DEC +43:08:10.267
Exposures	20L 12R 12G 18B x 600 secs @ -15C 0L 23R 22G 23B x 300 secs30L 30R 30G 23B x 60 secs Total Integration Time: 17hr 53min
Calibration	48 x 900 secs Darks* x47 Bias & x20 LRGB Flats *scaled to 600, 300 & 60 secs
Location & Darkness	Deep Sky West – amateur hosting facility near Rowe, New Mexico, USA SQM Typically >= 21.7
Date & Time	Q2 2021

M13 LRGB F2 CROP (Large)

Of all the things I’ve discovered since taking up astronomy, perhaps it is the presence and nature of globular clusters that has most surprised me. Bound closely together by gravity, these massive spherical collections of stars orbit the galactic core perpendicular to its plane. In the case of the Milky Way there are 150 globular clusters but they can be much larger in other galaxies, such as M87 which has some 13,000; clusters of clusters have also now been discovered in the Universe! Typically each cluster might contain a few thousand or tens of thousands of stars, although in some cases they can be much larger. Omega Centauri is the largest globular cluster in the Milky Way, being 150 light-years in diameter it contains 10 million stars; though clearly visible from Earth it can only be viewed from the Southern Hemisphere, which we unfortunately did not see when in New Zealand earlier this year.

MW & globs

Despite all the advances being made in cosmology, the origin of globular clusters still seems to remain quite uncertain. Characteristically the stars are all very old, typically in the region of 8 to 12-billion years and are of low metallicity i.e. they contain a low proportion of elements other than hydrogen and helium. At least some, such as Alpha Centauri, are thought to have condensed from dwarf galaxies and such a process may currently be taking place within the large Magellanic Cloud – which we did see in New Zealand! In other cases it is thought that the clusters have probably originated independently and were subsequently captured by the relevant galaxies. However, their very old age – sometimes nearly as old as the universe itself – origin and relationship to galaxies remains intriguing. For these and many other reasons I personally find globular clusters fascinating, probably more than any other astronomical feature, amazing as they too may be.

Globular Clusters May 2018: M3, M13 & M92 (red circles) + Others (yellow circles)

From time-to-time I’ve tried imaging various globular clusters but have not been satisfied with the outcome. Now using guiding, plate solving and the high-resolution ZWO1600MM-Cool camera, it was time to give it another try this spring, when some of the best clusters are present in the northern night sky.

M3 LRGB Final (Large)

First up was M3 (Final image above), the very first Messier Object to be discovered by Charles Messier himself in 1764. Consisting of 500,000 stars, between 8 and 11-billion years old and spanning some 220 light-years, M3 is one of the largest and brightest (absolute) globular clusters associated with the Milky Way – about 300,000 times brighter than our Sun. It is noteworthy that the cluster contains some 274 variable stars, the highest number of any clusters, as well as a relatively high number of ‘blue stragglers’ – young main-sequence stars that appear to bluer and more luminous than the other stars in the cluster and are thought to be formed through stellar interaction of the older stars.

M3 LRGB Crop (Large)

With these attributes it is not surprising that M3 is considered a popular target in astrophotography (cropped image above), likely surpassed however by M13 AKA the Great Globular Cluster in Hercules (cropped image top-of-the-page), which conveniently follows M3 in the same area of the sky about 3-hours later (together with nearby the globular cluster M92). And so having bagged M3 it was time to turn the telescope and camera towards M13 (Main image below). Discovered by the eponymous Edmond Hailey in 1716 (he of Hailey’s Comet), seen from Earth M13 is slightly brighter than M3 with a wide range of star colours that certainly makes for an exciting image. At 11.65 billion years old, M13 has been around almost three times as long as the planet Earth.

M13 LRGB Final (Large)

Since starting astrophotography I like to try my hand at imaging a globular cluster at least once each year but hitherto with disappointing results. This time I’m pleased with the outcome, especially M13 which is surely one of the most magnificent objects in our night sky; as a bonus there are also a few galaxies in the background of both the M3 and M13 images too. It is therefore fortunate that for those of us in the higher latitudes of the northern hemisphere the Great Globular Cluster in Hercules can be seen all-year round, though is at its highest and therefore best position between May and September – thereby inaccessible for the Kiwis who are instead compensated by Alpha Centauri! I expect to be back again next year to marvel at these amazing and enigmatic objects, if not before.

M3 Location Crop

	IMAGING DETAILS
Object	M3 (NGC 5272)
Constellation	Canes Venatici
Distance	33.9 million light-years
Size	18.0’ or 220 light-years
Apparent Magnitude	+6.2

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 x 8 + ZWO LRGB & Ha- OIII-SII 7nm filters
Capture & Processing	Astro Photography Tool + PS2, Deep Sky Stacker & Photoshop CS2
Image Location	Centre RA 13:42:23 DEC 28:22:50
Exposures	24 x 180 sec L + 10×180 sec RGB (Total time: 162 minutes)
	Unity @ 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^th + 6^th May 2018 @ +23.00h

M13 Location Crop

	IMAGING DETAILS
Object	M13 (NGC 6205)
Constellation	Hercules
Distance	>=20,000 light-years
Size	20’ or 150 light-years
Apparent Magnitude	+5.8

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 Location	Centre RA 12:39:59 DEC -11:37:20
Exposures	20 x 180 sec L + 15×180 sec RGB (Total time: 195 minutes)
	@ Unity 139 Gain 21 Offset @ -20^oC USB 40
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	6^th + 7^th+ 9^th May 2018 @ +00.30h