Category Archives: widefield

Widefield Heart, Soul & Double Cluster

Image centred at:
RA: 02h 44m 19s
Dec: +61° 17′ 24″
Field is 15°x10°.
(Plate-solve by nova.astrometry.net)

Taken on the night of the 25th November 2017 from West Oxfordshire, this image is a widefield rendition of the Heart and Soul Nebulae (IC1805/Sh2-190 and IC1848/Sh2-199), which includes the Double Cluster (NGC 869 and NGC 884) in Perseus. 

Widefield image of Heart and Soul Nebulae (IC1805/Sh2-190, IC1848/Sh2-199) and Double Cluster (NGC 869 and NGC 884) and Surrounds

This was the first real test of a new widefield config that’s now driven by a Raspberry Pi 3 running KStars and Ekos under Ubuntu Mate. The RPi3 controls the camera: a Baader filter modded Canon 350d (with shutter control via a serial release cable); a Moonlite compatible, Arduino based motor focuser (with stepper driven belt drive for the lens) ; and the Losmandy GM-8 mount it all sits upon. I can remote onto the RPi using VNC to control the session as it goes, and Ekos does everything including pointing and plate-solves, camera control and autofocusing. Everything is mounted on a somewhat Heath-Robinson arrangement on a standard Losmandy dovetail (lots of velcro pads!).

Within the camera is an IDAS P2 filter – this is a multi-bandpass, light pollution suppression filter that allows for an increase in contrast between deep sky objects and the background sky levels – it isn’t a substitute for full narrowband filters, but it at least allows an improved colour rendition of the target. It’s held in an MFA (mount filter adaptor) that screws into a small hole inside the camera body, holding the filter between the EF lens and the flip mirror. 

Exposures here were 5 minutes long each at ISO400 f4.5, with 45 subframes in total – combined exposure is 3h45m. Reduction and processing took place in Pixinsight, with only a small bit of amp glow removal in Photoshop. 

Annotated widefield image of the Heart and Soul Nebulae the Double Cluster and surrounds.

An annotated image showing the position of deep sky objects, coordinates and constellation figures/boundaries is also shown. There are, however, several objects that aren’t included in the labelling here – the reflection nebula LBN 142.14+01.97 in Camelopardalis is just visible to the left (east) of faint emission nebula Sh2-202. Open cluster Stock 2 is located (just) in Cassiopeia (to the right of the constellation label text!). And, though labelled up as SH2-191 and Sh2-197, the obscured local galaxies Maffei 1 and 2 are just visible as small, reddened smudges south of the Heart. 

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 f1,8USM 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.