Category Archives: astronomy

Conjunction – Moon and Jupiter

A very quick post of the conjunction tonight between the Moon and Jupiter. I find these types of conjunction notoriously hard to photo, especially close to full moon. This is mostly due to the wide field required and the difference in brightnesses between the two objects.

I’ve tweaked the curves a little within Photoshop to allow both objects to be displayed without blitzing out the lunar details – but the eye is much better at coping with these scenarios with its non-linear response and massive dynamic range!

The wider field of the Nikon lens for these photos shows just how good telescope optics are as well compared to “standard” DSLR lenses – there is a fair bit of blue fringing around the moon’s eastern limb, which isn’t particularly obvious in photos through the Takahashi FC60 or the William Optics FLT110.

Moon Jupiter Conjunction - 23rd Feb 2016

M42, The Orion Nebula in H-Alpha (work in progress)

RA (centre): 05h 35m 10.9s
Dec (centre): -05° 28′ 54.4″
(Results from nova.astrometry.net)

On February 10th, I managed to get some first data on a project in imaging the Orion Nebula with the FLT110/ST2000-XM combo. I had a fair bit of equipment issues here before starting – I have changed scope and was trying a newer PC. I had issues in getting the computer to connect to the ASCOM focuser and so resorted to an old laptop, thus wasting time.

I also had some guiding issues with PEC on – I think this is related to balance (the mount should have been more weighted towards the east) – and not to mention the object skirting the trees resulting in some spurious guiding results and the loss of 6 frames…

Finally (!), it became apparent when doing the flats that there was frosting on the chip – I’m not sure if this was the case before (though it doesn’t show), but this did mean I needed to run the flats at 2C, rather than -20C like the lights.

Even so, results are encouraging – this is the result of 27 x 3min with an Astrodon 6nm filter – this is one of the older narrowband range filters – running at -20C at f7. This needs much more data, as well as luminosity and colour channels to allow me to merge it into an L/Ha-Ha/R,G,B image  – the fainter regions are fairly noisy, which is not helped by short exposure, and the introduction of noise from the warmer flats, and dark frames for the flats.

Processing objects like the Orion nebula is always a little tricky, and I’ve tried to tame the vast dynamic range here by using luminosity masks in Photoshop (with four differently processed versions of the same image) to preserve the detail within the Trapezium, while also allowing me to bring out outer detail. If I can get a good enough night to get more data, I should be able to further blend in more data for the outside regions (possibly by using longer subs). The RGB combine should be interesting, and might need a bit of pushing of the H-Alpha data as it does get a bit diluted in the process.

M4, The Orion Nebula in H-Alpha - work in progress

High Resolution Near IR Lunar Imaging – 22nd Jan 2016

We’ve had some poor weather this winter so far for astronomy, but we’ve had some clearer nights in the last week, but with the moon at a fairly full phase. So I’ve been working with the 14″ SPX350 in honing my high resolution lunar work a bit.

I had two fairly average sessions working with the ZWO camera in unfiltered mode, but suffered a lot from poor seeing (potentially due to thermals from houses I image over) especially with stacks coming out with “ghost craters”. However, for this run of images, I used an Astronomik ProPlanet 742 filter I have just purchased (this is a near IR filter passing wavelengths longer than 742nm).

This has given a very good set of results – with three images surpassing the resolution I’d previously been able to get – and working at a focal length around 3200mm too by using a Meade series 4000 barlow lens in front of the camera and filter (giving a resolution of about 0.24″/pixel). Previously, I’ve only got good results at prime focus.  From a first time using it, it certainly appears that this filter does help with larger apertures where seeing is not perfect. Images, while not totally unaffected by seeing, seemed a lot more stable in terms of high speed jitter or double vision on craters.

Images were taken around 98% illumination so all the images are from areas around the eastern limb of the moon – with limited targets available and with cloud rapidly rolling in, the session was somewhat curtailed!

Pythagoras:Pythagoras - 22/01/2016

Grimaldi, Hevelius, Cavalerius:

Grimaldi, Hevelius, Cavalerius - 22/01/2016

Phocylides, Nasmyth, Wargentin and Schickard:

Phocylides, Nasmyth, Wargentin, Schickard - 22/01/2016

 

Lunar Imaging – 20th Dec 2015

A long time since the last post (and still needing to properly process the lunar eclipse images I took at the end of September) I finally got the 14″ re-mounted and collimated for some lunar work.

Images were taken through an Orion Optics SPX350 at f4.52 (prime focus) using a ZWO ASI120MM. Images were stacked with Autostakkert, processed in Registax 6 and Photoshop.

First up: The South Pole region (including Tycho, Clavius and Moretus)

Lunar South Pole - inc. Tycho, Clavius, Moretus

Copernicus and surrounds:

Copernicus and Surrounds

Rupes Recta in Mare Nubium (also showing Rima Birt and the lunar dome Kies Pi):

Mare Nubium, Rupes Recta, Rima Birt, Kies Pi

Mare Imbrium and Plato:

Mare Imbrium and Plato

M101 – Pinwheel Galaxy

Field centered at: RA: 14h 03m 12.6s, Dec: +54° 21′ 16.7″
Up: 178 E of N.

(plate solve from nova.astrometry.net)

The Pinwheel Galaxy, M101 is located in Ursa Major, and I found this a surprisingly tricky object to image – it has low surface brightness, with a lot of faint outlying regions. I also appeared to have some small issues with the flat fielding process here – there are a couple of very large dust bunnies in the raw data that haven’t quite been subtracted away and there’s a touch of clipping to deal with this. Add to this some faint colour gradients (attempted to sort out gradients!) and a couple of bright stars in the field and it became something very tricky to try and get right (and I’m still not 100% convinced that it’s truly there yet…).

The fainter galaxy to the right (east) of M101 is NGC5477, which is a dwarf galaxy at about the same distance (~20MLy). There are lots of fainter objects in the image as well: the brighter galaxy to the upper left of M101 for example is MCG+09-23-25, and there are also loads of other faint galaxies, galaxy groups and QSOs lurking in there. Using a solved fits file in Aladin is very instructive here!

I used fairly long exposure lengths (I was using the FLT110 at f7 here, a shorter focal length would be a major bonus in truth – at f4-5 this would be a much deeper image!). Exposure details are as follows:

WO FLT110 @ f7 on Losmandy Titan, ST2000XM cooled to -20C (images on 18 & 19-Apr-2015)
L: 4.5hrs (1×1)
R: 70min (2×2 binned)
G: 48min (2×2 binned)
B: 48min (2×2 binned)

The Luminance for the image was processed using a Lucy-Richardson deconvolution (3 iterations) using CCDSharp.

M101 - Pinwheel Galaxy in UMa (Luminance)

 

M101 - Pinwheel Galaxy in UMa (LLRGB)