Thursday, 25 March 2010

Siamese Twins

The Siamese Twins are a pair of overlapping and presumably interacting galaxies aka NGC 4567 & 8. Their magnitudes are approx. 11.7 and 12.1 and they are quite small, 4.6 & 3.1 arcminutes (respectively), because of their large distance of 120 million light years from Earth.
The pulses sent to the stepper motors that drive our 20" scope had just been adjusted to attempt to cut the wobbly, vibrating tracking, so I gave it a test on these fine objects. I did manage to get one reasonably steady 2-minute exposure, but on closer inspection there were slight star trails, in addition to the field rotation limiting the exposure. But overall it was no better, I'm afraid. I had to detrail most of the 30-second images that made up this final image, but a pleasing result nevertheless with a total exposure of 5 minutes at f/3 ish, with quite a misty sky just before moonset. Also in this image at top is NGC 4565 - a 12.0m, 3.2' galaxy and at bottom, IC 3578 - a 15.1m, 0.9', tiny splash of light.

Saturday, 20 March 2010

Gyulbudaghian's brightening

Here is an image showing the brightening of Gyulbudaghian's variable nebula, located at RA 20h 45' 55" and Declination +67º 57' 45" in Cepheus. There is clearly more of the cometary looking nebulosity north of the star PV Cephei. The image is a stack of 57 30-second exposures at ISO 1600 and f/3 on the 20" scope, taken on 8th March 2010. But the processing used non-linear stretches and an artificially created and edited flat field to give the most pleasing picture, so in no way is it quantitatively calibrated. It looks wonderful in such a large format and it's nice to have sort of discovered something changing up there in the stillness of space!

Sunday, 14 March 2010

The Air Pump

I am now going below the -30º Declination line to reveal a couple of galaxies in the constellation of Antlia, the Air Pump. Imaged from the UK, NGC 3100 and 3095 are both below 12th magnitude in brightness and -31º30' in declination. As you can see, with the low altitude, the atmosphere has shaken the stars into big disks, after realigning the Red, Green and Blue channels as a matter of course. I also spent ages messing around with the background subtraction, as the raw images were a bright milky brown. 27 x 15" f/3, f~1.5m, ISO 1600.

Galaxies in Pyxis

On my southern trawl, culminating a little after Puppis the Poop, comes the constellation Pyxis the Compass. It contained the fine galaxy NGC 2613 (11.2m) and faintly above it PGC 23977 (14.5m). Thanks to the huge aperture and excellent south horizon the telescope could cut through the large thickness of misty atmosphere.

NGC 2452 & 2453, Puppis

I turned the scope to the southerly declinations of Puppis for these interesting and glorious full-colour shots of the cluster and planetary nebula NGC 2452 & 3, respectively. Being near the milky way there are some beautiful star patterns, and a deep orange star on the right. The cluster looks like a backwards lambda to me and the planetary is a tiny or distant little pair of blue lobes.

Friday, 12 March 2010


Here's an animation of Makemake, from last Saturday and Sunday nights (March 7, 02:00 & 23:00UT) on the 20" scope. It appears surprisingly bright for an 16.8 magnitude object. Conditions were dark and transparent both nights and I was at quite a high altitude. This little heavenly body was surprisingly easy to find after having imaged Eris (see earlier post) as it lies close to the top dot-to-dot line of Coma Berenices. Makemake, which I believe is pronounced mak-eh-mak-eh, is a large minor planet over 50 A.U. from the sun, which puts it beyond Pluto's orbit, but nowhere near as far out as Eris. I acquired 29 x 30" images the first night, then another 11 the following night, when it was darker and clearer still. -- Hit play to reload the video as it's not set to repeat...and apologies for not adjusting the brightness.