Category Archives: astronomy

Widefield Imaging from France

Summer is traditionally a poor time for astronomy in the UK – it doesn’t really get dark in my location between late May and late July, and so I’ve not done a lot of astrophotography recently, though I have done a little bit of equipment work, cleaning, etc.

However, on a recent holiday to France (staying near St. Nathelène, near Sarlat-La-Caneda), I managed to do a little bit of widefield imaging work. I used a 350d and a couple of newly acquired lenses – a Canon 85mm f1.8 USM, and a Samyang 14mm. The 350d was modded when I bought it last year, though I have since added a Baader BCF filter to restore the focal point to allow me to use normal camera lenses with this camera body. One negative about this camera is that there are no 64bit drivers available, so I’m forced to run everything from inside a Virtualbox VM…(*)

Before the holiday, I built myself a camera mount for my GM8, based upon a spare dovetail I had. This has a Arduino driven stepper motor with a simple belt drive to focus the lenses – the system is based around the MyFocuserPro code using an Easydriver board. This has an ASCOM driver and can be nicely controlled from software like APT – this makes focusing relatively easy, though having liveview like on the 450d would be much easier!

Northern Summer Milky Way from Lacerta to ScutumFirst up is a widefield image of the summer Milky Way, stretching from Lacerta to Scutum – this is a stack of 12x5min exposures, taken through the 14mm Samyang at f2.8. Reduction and processing was done using Pixinsight, with slight tweaking in Photoshop.

This was the first image I’ve taken through this lens, and the first widefield work I’ve done in about 20 years (!). The lens is not perfect (in fact I’ve replaced it with another example that is better and doesn’t show the coma on axis here which I think it’s due to element decentering), but it has still given me probably the best widefield shot of the Milky Way that I’ve produced: digital photography makes such shots much easier than slide film in some ways, but not others…! Clearly visible are the dark dust lanes (the Cygnus rift) as well as emission nebula such as IC1396, the North America Nebula, the Pelican Nebula, and the Gamma Cygni complex. From nova.astrometry.net here is an annotated version showing the major constellation outlines – interesting here is that even astrometry.net can’t handle the lens distortions from such a wide angle lens.

Scutum Star Cloud, M11, M26 - 85mm USM CanonSecond image is actually the first image I have taken with this camera – this using the 85mm EF f1.8 USM Canon lens (at f3.5). This is a shot of the area around the Scutum star cloud, M11, The Wild Duck Cluster and M26. It was “only” 4×180 seconds – clouds rolled through after this point, but it was a good learning experience (I’d close the aperture slightly more, and go for longer exposure). Nevertheless, I think I’ve managed to tease out some detail here, though gradients were tricky to handle using DBE in Pixinsight, along with some corrections in Photoshop. More exposure would have helped enormously here, and I think I can improve the capturing of calibration frames in future.

Similar to above, shown here is an annotated image (from nova.astrometry.net) to show exactly what is in the image, and which highlights some of the various deepsky objects around the field of view.

(*) – More recently, I’ve been looking at kstars and ekos for camera control – this looks promising and should allow control of the camera, mount and focuser using a Raspberry Pi. 

 

 

Virgo Galaxy Cluster

Field centred at (platesolve by nova.astrometry.net):
RA: 12h 26m 15s
Dec:  +12° 52′ 36″
Up is -177 degrees E of N

M86/M84 Region of the Virgo Galaxy ClusterThe Virgo Galaxy cluster is a large nearby cluster of galaxies, that spans over 8 degrees of sky, and consists of over 1300 member galaxies. The cluster forms part of the Virgo super-cluster, of which the Local Group (with the Milky Way, M31, and M33) is an outlying member. 

The cluster is approximately 50MLy distant, and is comprised of three main clumps, with the image here displaying the M86 “subclump” of the “Virgo A” clump. M87 (Virgo A itself), is just off the frame to the lower left. The three largest galaxies in the image above are M86 (centre), M84 (right) and the interacting pair NGC 4435/4438 (left – otherwise known as “The Eyes”). These galaxies make up part of the famous “Markarian’s Chain” which is a series of bright galaxies extending off frame to the top left (north-east). Virgo Cluster - M86/M84 Region, Reverse AnnotatedAlso present in the image above are NGCs 4387, 4388, 4402, 4407, 4425, as well as several IC objects (including the odd blue irregular galaxy IC3355 at the top of the frame) and countless faint objects – some of which are highlighted in the annotated reversed image with galaxies highlighted from the SDSSR8 catalogue down to magnitude 20. 

“The Eyes” make an interesting pair – the smaller (NGC4435) is a barred lenticular galaxy (an intermediate between an elliptical and spiral). The larger NGC4438 is the most distorted of all galaxies in the cluster – with much of the disruption apparently caused by a past interaction with NGC4435. The detection of gas linking NGC4438 and M86 suggests that at some point all three galaxies have had past interactions. Additionally, there is some question as to whether the core of NGC4438 is powered by starburst (which may be as a result of the previous interactions), or whether it is home to an Active Galactic Nucleus, powered by a black hole. 

Data was taken over several nights during March and April 2017 from West Oxfordshire, UK using a WO FLT110, FLAT4 reducer, ST-200XM and Losmandy Titan. LRGB exposures were 240 (24x10min) : 75: 70 :70 (RGB in 5 min subs, 2×2 bin). Unfortunately, the flats didn’t reduce well here, so there was quite a bit of work in trying to eliminate gradients across the image – this may have restricted a little what I was able to pull out of the image data.

M48 – Open Cluster in Hydra

Field centred at (plate solve by nova.astrometry.com):
RA: 08h 13m 48s
Dec: -05° 44′ 32″
Up is 3.32 degrees E of N

M48 - Open Cluster in HydraFaintly visible to the naked eye, M48 is a large open cluster in the sprawling constellation of Hydra, the Water Snake. This was originally one of the “missing” Messier objects – Charles Messier catalogued this object some 5 degrees off in declination, but this cluster was independently observed by Caroline Herschel in 1783 – the connection between the two only being made some 150 years later than Messier’s original observation.

Interestingly, in this image, there is a hint of a nebular structure just to the right (west) of the cluster (about 75% of the way across the frame as shown). It’s hard to see if this is real, or an artefact due to inaccurate flat reduction/reflection – the only way to prove this is by taking deeper exposures, and moving the scope around to ensure no systematic errors. Given the poor weather prior to taking this image, it seems unlikely to happen in the near future!

Images were acquired on 24th March 2017 from West Oxfordshire, using an ST-2000XM through a WO FLT110 on a Losmandy Titan. Exposures were R:G:B = 90:70:70 in 5 min subs, with reduction and processing in Pixinsight and Photoshop. 

M67 – An Old Open Cluster

Field Centred at (plate solve from nova.astrometry.net):
RA: 08h 51m 29s
Dec: +11° 49′ 26″
Up is 90.7 degrees E of N

M67 - Open Cluster in CancerM67 is an open cluster located in Cancer – it is much smaller than it’s larger neighbour M44 (The Beehive Cluster/Praesepe), and while not the oldest open cluster (with an age estimated to be 4 billion years), it is close at about 800-900ly distance.

None of the stars are bluer than F spectral class (with the exception of the 30 or so blue stragglers found in the cluster), and there is limited extinction from dust/soot, which makes it an excellent target for study, along with a similarly useful target in NGC188. 

The set of images taken here was also a first test for a new setup in being able to guide using a newly acquired TS OAG9 – this is a very low profile off axis guider and allows me to guide in front of the filters – while this isn’t always required, it makes holding a guide star much easier, especially for narrowband work where guiding with the guide chip in the camera can be nigh-on impossible! This setup allows me to guide using PHD2 and image using APT (with the advantage of having it’s own focus control and platesolving capabilities, as well as Astrotortilla being able to take images to make platesolving/mount alignment much easier). 

Images were taken on 15th and 20th March 2017 from West Oxfordshire, using the SBIG ST2000XM on a William Optics FLT110 working at |f5.7 with the FLAT4 reducer. Guiding was performed off-axis by my ASI120MM, controlled by PHD2. 

Exposures were:
R:G:B = 90:75:65 (all in 300sec subs). 

Reduction/Processing in Pixinsight and Photoshop CS4.

M31, NGC206 and the Bologna Catalogue

NGC206 Region in M31 - Lum ChannelPresented here is a bit of a “nonsense image” of the Andromeda Galaxy, M31, that I grabbed early in the evening of the 22nd Jan 2017. This was a quick run, mainly while I was waiting for another target to clear the tree near my observatory…!

However, even in an image like this, which only consists of 14x5min exposures through a luminance filter, there is lots to be explored – first it gives me a good idea about future plans for a mosaic (though this will have to wait until the autumn now, and may be a major undertaking…). It also gives a good view of NGC 206, which is a bright star cloud in M31, and I plan to image this alone at longer focal lengths later on. Also, it allows me to explore objects in the Bologna Catalogue 1.

NGC206 Region in M31, with Bologna Catalogue Globular Clusters AnnotatedThis catalogue  is not one that comes immediately to mind when talking about deep-sky objects – but it is a very specialised list describing globular clusters (GCs), candidate GCs and previous candidate GCs in M31. The up to date version of the catalogue is freely available on the Bologna Catalogue website and can be downloaded, manipulated and used as a source of information for the Annotate script in Pixinsight. Presented here in negative format is the south west region of M31, with overlaid markers for the confirmed GCs in the Bologna Catalogue v.5 (with associated V magnitudes) in red, as well as a few small PGC galaxies that loiter in the field marked in light blue. There are 181 marked objects alone in this field – most of which have been successfully captured using just a small 4 1/2″ refractor!

Image details:

ST2000XM, William Optics FLT110 + FLAT4 reducer
14x5min, L filter
Reduced and processed in Pixinsight

References

1. Galleti S., Federici L., Bellazzini M., Fusi Pecci F., Macrina S.: “2MASS NIR photometry for 693 candidate globular clusters in M31 and the Revised Bologna Catalogue (V.1.0)”, Astron.&Astrophys., 2004, 416, 917 (G04)