Observations of comet C/2011 W3 Lovejoy

Made from San Pedro de Atacama, Copyright Alain Maury 2011

December 20th in the morning

Tried to observe the comet, didn't see anything with binoculars, tried to make images with QSI camera and 100mm F/2 Canon lens and Z filter, and nothing seen.

Saw Mercury, then Antares, then Epsilon Scorpion, and the comet was supposed to be 4° lower. I have the Andes to the east, so can not see to the horizon. The comet was up when the sky became very bright, so no luck.

December 21st in the morning

Came at the time when the comet was supposed to be up above the Andes. Which means was already pretty much in twilight. Had prepared the QSI camera with the same lens as yesterday and a I filter this time, but then saw the tail quite long with the naked eye, and decided to shoot with my Canon 5D MkII which reads a little bit faster than the QSI CCD camera. The following image is a good compromise and give a pretty realistic impression of the view over the Andes. For your information, behind the tree, invisible there, is the ALMA base camp.

Taken at 5h59 local time (meaning 8h59 UT), exposure 1/4th of a second with 1600 ISO in raw mode. Canon 100mm F/2 lens (opened at F/2) focused with live view on the moon.

Reduced here by a factor of 4


Following is an annotated version


I tried to remove the sky background (well, it is 7h30 in the morning, not too clear) and increase the contrast. The tail of the comet goes at least to SAO237637, and the length of the tail measured on this image is a bit more than 8 degrees. This is only a 1/4th of a second, tomorrow I'll start the observing earlier to see if it can be traced further away.


I tried observing visually to detect the nucleus of the comet, but did not see anything with the 12x30 stabilized Canon binoculars, then nothing with a 20cm F/5 reflector with 30x magnification, and with a 45cm F/4.1 100x, saw at one moment one star in the correct region, but could not confirm at that moment (it was starting to get really bright) if it was a field star or the nucleus of the comet, it looked as blurry as can be a star very low on the horizon, so can't tell. Anyway still far from producing astrometry on the nucleus, maybe it does not exist anymore....

December 22nd in the morning...

The sky was cloudy over the Andes, so thought it would not be observable. Then before going to bed at 4, looked on the all sky camera of the observatory and saw that were two things visible to the clouds... Went outside, one was the moon, the other was the comet, so decided to take an image anyway, then make a time lapse. This first picture is a 30s exposure with a 50mm F/1.8 lens at full aperture (3200 ISO). The bright light behind the trees is the ALMA base camp. The moon, and the comet, which this morning had a tail 16° long. Still no nucleus observed, so still no astrometry...

Lovejoy above the Andes from Alain Maury on Vimeo.


Another, "bluer" version made using the raw frames

Another rendition from Alain Maury on Vimeo.

December 23rd in the morning

I started earlier this morning, except the weather is deteriorating... Made a time lapse with the 5D MkII and the 50mm stopped down at F/2.8, extracted this image from it :


And here is the time lapse :

Comet Lovejoy from Alain Maury on Vimeo.