Rosetta darts across the sky: images taken last nght
We received several images and animations from Kristin this morning, of observations that she's been carrying out from ESA's Optical Ground Station in Tenerife, Spain as the satellite approached Earth. The animation above comprises images recorded 13 November, 03:05 to 03:25. It comprises 18 images with an exposure time of 15 s and a separation of 69 s. The field is located in the constellation of Cetus and has a size of 10 x 10 arcmin. The telescope was tracking Rosetta so that the spacecraft appears as a dot in the centre of the image while the stars appear as stripes.
This image was captured at 03:59 CET, 13 November, with an exposure time of 2 minutes. The field is located in the constellation Cetus and spans 10 x 10 arcmin. The telescope was tracking the stars so that Rosetta appears as a stripe in the centre of the image while the stars appear as dots. Rosetta moves 3 arcminutes during the 2-minute exposure. Compare the movement with the image above, taken at 22:58 CET. The brightest star in the top left corner of the image has a magnitude of 12. This is the last image taken before Rosetta's closest approach to Earth, immediately afterwards its elevation fell below 18 deg which is the limit of the telescope.
This still image was taken at 22:58 CET on 12 November. The total exposure time was 2 minutes. The field is located in the constellation of Cetus and has a size of 10 x 10 arcmin. Rosetta appears as a dot in the centre of the image while the stars appear as stripes. The stars move for almost 1 arcminute during the exposure. The brightest star in the bottom left corner of the images has a magnitude of 15.
Kristin's still there tonight as well, to see if Rosetta can be detected as it recedes. But the spacecraft will be much
weaker in the sky than during the approach because an observer on
ground will be looking at the unilluminated side of the solar arrays.
Rosetta will have risen high enough for the telescope to point toward
it at 04:30 CET. Its elevation will then increase; dawn starts shortly
after 07:00 CET.












17-11-2009 • 11:23:27
Here is my attempt to get a picture of Rosetta on the night of Nov 12. I was lucky enough to get a clear sky.
http://mat.uab.cat/~jmm/200911-rosetta_3rd_earth_swby/rst1845_r.gif
I've written the details of the observation here, just in case they might be useful
http://mat.uab.cat/~jmm/200911-rosetta_3rd_earth_swby/
It seems that Rosetta was a little higher than predicted by the Horizons ephemeris. Is this possible?
I would like to congratulate the Rosetta and the blog teams for their fantastic job and making all this information available to everyone.
17-11-2009 • 15:48:45
Hola Josep Maria Mondelo!
Thank you for observing Rosetta during Earth Swingby 3. Your images are great!
You have reported an offset between the observed Rosetta position and the prediction by Horizons. I would like to tell you that I have not noticed anything like this. I have used Horizons myself (latest data retrieved on 4 Nov) and plotted the positions into star charts (higher magnification charts than the ones that were published on the blog). On the images that we took at ESA's OGS Rosetta always was at the expected position relative to the stars.
23-11-2009 • 22:03:47
It was a completely silly mistake on my part. I used km instead of m for the height of the observatory location. Using the correct units, Rosetta is exactly where predicted. Sorry!
23-11-2009 • 10:35:53
Hi Kristin.
Thank you so much for your answer. My images are not as great as yours :-) I'll try to find out was was wrong.