Category Archives: astroimaging

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

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)

M35 & NGC 2158

Field centred at: RA: 6h 08m 25.2s, Dec: +24° 15′ 06.2″
(plate solve from astrometry.net)

M35 and NGC2158 are a pair of open clusters which, similarly to the more famous h and X Persei, are viewed nearly on the same line of sight from Earth. M35 is somewhat younger (as evidenced by the predominantly blue stars as compared to the older yellow stars in NGC2158), and a lot closer to us – while NGC2158 is more compact with more stars in the same volume.

M35 & NGC2158 in Gemini
M35 & NGC2158

This exposure was taken on the 8th February 2015 but was somewhat shortened by fog rapidly rolling in, and hence the rather short total exposure:

ST2000XM, FLT110, Losmandy Titan
LRGB: 20:9:9:9 each in 1min subs.

C/2014 Q2 (Lovejoy) – 8th Feb 2015

Field centred at: RA 02:00:07, Dec +45:10:35.
Field size: 51.4 x 38.9arcmin; Field rotation: up is 179.9° E of N
(plate solve by local astrometry.net instance)

Comet Lovejoy was discovered in summer 2014 by Terry Lovejoy and is a long period comet and had a period of about 11000 years (now reduced to about 8000 years after this approach to the sun.

C2014-Q2-20150208.jpg
Comet Lovejoy (C/2014 Q2)

 

C2014-Q2-20150208-neg-tail.jpg
C/2014 Q2 (Lovejoy) – in negative, showing tail detail

 

Images were taken on the evening of the 8th Feb 2015 using an ST2000XM  through a William Optics FLT110 on Losmandy Titan. 26 each of L, R,G,B filtered frames, each taken in that sequence (so each frame of each filter starting about 5 minutes apart).

Processing of the colour image with the comet “frozen” against the stars followed Bernhard Hubl’s method of processing the comet. The negative image which enhances the tail was produced by a median combine of the data while aligned on the comet itself rather than the background stars (the comet was moving at about 2arcsec/min at the time).

 

Circumzenithal Arc

Circumzenithal Arc - Abingdon, 15th Aug 2008

Saw this circumzenithal arc on Friday 15th from Abingdon. Looks much like an upside down rainbow above the sun (which needs to be lower than 33 degrees or so for this to occur) – it occurs due to horizontally orientated ice crystals high in the upper atmosphere.

Only had the camera on my phone so the image is a bit ropey, but hopefully clear enough…