Comet C/2007 Q3 Siding Spring
Report from James Abbott:
This image of Comet C/2007 Q3 Siding Spring was taken at Rivenhall Observatory last night and (just!) shows the split in the nucleus that was first picked up on March 17th by Nick Howes of the Wiltshire Astronomical Society using the Faulkes Telescope.
The fragment that broke off is best seen in this negative of the image and is the small dark dot just to the lower right of the main nuclear condensation of the comet. For comparison the brightest of the line of three stars just above and to the right of the comet is mag 15.1 – the fragment is clearly much fainter than that.
The image is a stack of ten 30 second frames with dark and flat frames subtracted. Exposure start time was 22.38 GMT on 4th April using a 300mm f4 newtonian at prime focus and an ATIK 16IC CCD camera. The frame is 14 x 11 arc minutes and North is at top.
I could not see the comet visually so it is probably 12th mag or fainter now – but clearly still showing a lot of activity despite its distance – it is now over 2.5 AU from Earth (that’s approximately 230 million miles) and over 3AU from the Sun. On the positive image, the broad tail went off the frame – so at least 6 arc minutes long.
Out of interest – I thought the little streak at the lower right hand corner of the image was an artifact but after checking with observatory plates it is actually a faint edge-on spiral galaxy.