Continuing with the cometary theme, another favorite comet photograph from the past…
I took advantage of a clear evening to do a little more driveway astrophotography. The target was comet 144P Kushida. The comet is nearly at the Zenith in the evening, very conveniently placed with ample time to take more than a few frames.
The setup was fairly typical for me, the Canon 20Da and the TV-76 shooting for over 40 minutes (10 frames at 4 min each). The frames were calibrated and stacked in Images Plus and post proccessed with Photoshop and FITS Liberator. I followed Jerry Lodgriss’ instructions for preserving and enhancing the star colors with pleasing results. I suspect I will be using this technique more in the future and star colors are something that has always frustrated me.
Since I have a CCD camera co-boresighted with the TV-76mm refractor I was able to use the CCD to take frames simultaneously. This arrangement is convenient as I can use the CCD for finding and framing the target, the field of view is very similar between the two cameras. I spent time early in the evening to carefully align the CCD to match the view in the refractor. There is also a small 10cm SCT in the setup for use as a autoguider scope, but I have not been using this lately. I suspect I will try some longer exposures of C/2007 N3 Lulin in a few days and will need the guider.
The comet itself was fairly straightforward, a round coma with no real tail, a slight off centered shape to the coma. The cyanogen green comes through nicely, very apparent when processing the color planes separately. It is moving fairly slowly, for the DSLR photo I aligned on the stars and only had slight issues with the comet trailing. For the CCD image I aligned the images on the comet, showing some trailing in the stars.
The CCD frames do not show any sign of a tail or other structure either. This is not surprising as 144P Kushida is usually a fairly dim comet that is bright only due to material from an outburst a couple months ago. It is not a highly active comet with jets, tail and all of the other features that can make comet photography so interesting.