彗星2006P1在NASA STEREO-B (Behind) 上显示出一条7度彗尾，而且有许多射线状的东西。
This image (click for larger version) from the SECCHI/HI-1B instrument on the NASA STEREO-B (Behind) spacecraft was taken on January 11, 2007 just after the door covering the instrument was opened for the first time after the STEREO launch on October 26, 2006. The image is dominated by a spectacular view of comet C/2006 P1 (McNaught) The full field of view of the HI instrument is centered at about 14 degrees from sun center and is 20 degrees wide. (Note that the image opposite is a close-up view of the comet.) The comet tail is approximately 7 degrees in length and shows multiple rays. The coma is saturating the image even at the shortest exposure time of 1 sec. The images are full resolution 2048 x 2048, which corresponds to 35.1 arc sec/pixel. The SECCHI/HI instrument was built by a consortium consisting of NRL, the University of Birmingham (UK), Rutherford Appleton Laboratory (UK) and Centre Spatiale de Liege (Belgium).
This was the sight that greeted us when we opened the HI-1B doors for the first time today. Wow!! Just as a note to you all, the reason we can see this object in HI-1B is because the 'B' spacecraft is currently rolled (for operational reasons) at a roughly 140-degree angle. Ordinarily we would not have been able to spot the comet.
This is a full-field (but not full-size -- I rescaled it) image from the SECCHI HI-1 B camera showing comet C/2006 P1 (McNaught). Note the saturation in the HI images shows itself as vertical streaks instead of the horizontal streaks we see in LASCO. This is due to the way the HI CCDs are read by the instrument.
As many of you are aware, the recent discussions of this comet have centered around the question "how bright?". Well right now we have not had chance to analyze the images and determine a magnitude (we're still somewhat in shock), but as a benchmark, it appears to be brighter than Venus is in our HI-1 A images.
This is another close-up image of the comet. I have rescaled the image to show more fine structure in the tail, but it has dramatically increased the apparent saturation in the comet head. Note also that this was a longer exposure image (twenty-four seconds) so the saturation is pretty bad anyway. The glare in te lower-right corner is from the Sun's F-corona.
[ 本帖最后由 suhuasky 于 2007-1-12 08:44 编辑 ] |
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