10th August 2010

M27 Dumbbell Nebula
10" Newtonian, SXVR-M25C, 12*5 minutes
Guiding with OAG and Lodestar. Guiding was quite good, but the image is spoiled by the focus being very poor. Focus on the target before M27 was good, but I did not check focus after slewing to M27. Bad mistake!

M57 Ring Nebula

10" Newtonian, SXVR-M25C, 7*5 minutes
Good focus but guiding was a bit off, hence elongated stars. M57 is only 4 arcminutes in size - 32 would fit across one frame. This image is a crop of the central part.
It is my first image that shows 3 stars within the nebula. Only the central star (mag 15.75) is actually inside the nebula. The other two are probably foreground or background stars.

15th August

M13 Globular Cluster
10" Newtonian, SXVR-M25C, 7*6 minutes
First attempt with the guiding to the mount set to 'Telescope' and not 'Ascom Direct'. Guiding in RA was phenomenally accurate, with errors below 0.2 pixels. DEC guiding was equally good at times, but then excursions up to 1.5 pixels would ruin the frame, resulting in many frames being discarded.

18th August 2010

M27 Dumbbell Nebula
10" Newtonian, SXVR-M25C, 6*6 minutes
Focus good this time, but only the first frame was in clear sky - then wispy cloud came in.

23rd August 2010

M92
10" Newtonian, SXVR-M25C, 13*6 minutes
Focus drifted badly, full Moon and windy conditions conspired against me.

29th August

M57 Ring Nebula
10" Newtonian, SXVR-M25C, 19*6 minutes
Bright Moon raised the sky background. Focus and tracking were good but stars still a bit elliptical, probably due to focuser tilt. However, the central star is the smallest and sharpest I have yet obtained, and there is some detail visible in the wispy green stuff inside the nebula.


Different processing, using only the best 7 frames.
Compared with the Hubble image:
 
Variable star

Interesting star near M57. It is quite prominent in the DSS image, but faded considerably in my image.

Cartes du Ciel gives the star as GSC2643.1656, magnitude 12.63+/-0.40
Stellarium gives the magnitude as 15.35

RA 18h54m10.01s
DE +32°49'51.2"











Rob Januszewski pointed out that the star is actually RX Lyrae, which is a Mira type variable star.
The magnitude varies from 10.9 to 16.0 over a period of 247.82 days.
This prompted me to dig out old images of M57 and look for the star. In each image the star is at the centre.
 3rd July 2008 17th June 2009
15th May 2010 2nd September 2010
 
These images were made with different cameras, different telescopes and different exposure times, so do not constitute 'scientific' images.
However, the change in brightness is obvious, with May 2010 being the brightest.
(Mira variables are red giants whose surfaces oscillate in such a way as to increase and decrease in brightness over periods ranging from about 80 to more than 1,000 days).