Tag Archives: FLT110

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.

Comet Lovejoy (C/2014 Q2)


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).