C/2011 W3 (Lovejoy): A morning comet visible in binoculars from the southern hemisphere
This comet not only survived perihelion, but brightened considerably. On December 19 it was reported to be magnitude -0.5 with a 15-degree tail. Each morning it will rise earlier, giving us a better view before twilight overwhelms it. But at the same time it should fade with each passing day. It may become a naked-eye object, depending on how quickly it fades.FINDER CHART
LatitudeVisibility December 3Visibility December 10Visibility December 17Visibility December 24Visibility December 31Nights Visible
55o N Not visibleNot visible
40o N Not visibleNot visible
Equator Very low in the eastern sky during morning twilight at ~05:10Very low in the southern sky during morning twilight at ~05:10-31
30o S Very low in the eastern sky during morning twilight at ~03:40Fairly high in the southern sky during morning twilight at ~03:30-31
2011 W3 (Lovejoy) has unexpectedly survived perihelion! This comet is a binocular object near the end of December, visible just before dawn from the southern hemisphere.
http://sungrazer.nrl.navy.mil/images/lovejoy/lovejoy_20111215b_cor1054.png Comet Lovejoy in STEREO/SECCHI COR-1B. Clicking this will take you straight to a ~7MB Quicktime movie. If it doesn't work, right click here and save the movie to your computer. 1630UT: Things are starting to calm down a little now and we can begin the analysis phase of this event. Lovejoy is still in the HI-1 fields of view on both STEREO spacecraft, but it should be leaving those sometime today. It will continue to be visible in STEREO/SECCHI HI-2 for a while yet, but that's a very big field of view, so unfortunately the best of the show is over. Well, from space at least, because as it recedes from our electronic eyes-in-the-sky, it is becoming an increasingly visible object for Earth-based observers. Regrettably this viewing opportunity is limited to those in the Southern Hemisphere, but many of these astronomers and astro-photographers are sharing their images and movies online. Lovejoy should continue to climb in the morning sky for those folks and, despite an apparent fading of its nucleus over the past few days, its tail certainly has the potential to become truly spectacular.
So here's something I hadn't shared with you yet: a view of the comet from STEREO/SECCHI's COR-1 instrument. This is actually a very interesting movie that shows nicely how this object moved. For the 5% of you that haven't done so already (I know why people come here, and it's not just for the narrative...), please go ahead and watch/download the movie opposite.
This is the SECCHI COR-1 (inner coronagraph) image on the STEREO-B satellite. From the perspective of STEREO-B, the comet moved diagonally across the face of the Sun, looped around it, and re-emerged from around the back. The comet is obvious to see as it enters the camera in the lower right. We lose sight of the head of the comet at ~2300UT as it disappears behind the occulting disk. (We superimposed a Sun image on the movie -- this camera doesn't actually see that.) Then at around 0130UT we see the bright tail of the comet appear again in the upper-left of the image and continue to move out. Here's the fun part: this is not the comet itself! Keep watching, and at ~0530UT you'll see the comet -- minus a tail! -- emerge on the right hand side of the central disk and move towards the lower-right of the image, finally exiting at ~10:45UT.
So if the comet re-emerges on the right without its tail, does that mean the bright thing that flew out of the top-left of the image is its tail?? Absolutely! I summarize the situation here. What we're seeing is the comet streaming into our field of view with a vast cloud of dust and ice trailing in its wake. The comet reaches the Sun, loops sharply around it, and head out around the back of the Sun. But the tail material we see has already left the comet and is just going to carry on in a straight line from the time it was ejected, while at the same time be pushed away from the Sun by the radiation pressure from the Sun itself. So we're actually seeing the tail material sweeping out towards us, while the comet races off to do its own thing.
OK, why does Lovejoy not have a tail after it reappears? How did it get torn off? Well it didn't actually get "torn off", as it was never physically connected to begin with, but what likely happened was that the dust and ice produced by the comet was no longer able to follow the comet in its path as the relatively dense and incredibly hot solar corona "captured" (probably instantaneously evaoprated) any dust and ice particles released by Lovejoy's nucleus. As Lovejoy gradually left the intense near-Sun environment, the dust and ice were gradually able to rebuild, now free of whatever impeding factor the solar corona was presenting it. Within a matter of hours it was again sporting a beautiful tail.
The physics of all of this are uncertain and somewhat unknown. We are only just beginning to start unravelling the mystery, and this is going to take many months and many scientists. But be assured that as soon as we publish new results, I will certainly present them here on this site (minus the inevitably indecipherable science jargon that gets used in scientific papers).
http://sungrazer.nrl.navy.mil/images/lovejoy/20111218_104901_tbh1A.png Comet Lovejoy in STEREO/SECCHI HI-1A. See below for links to the movie and the individual images.
I have received several inquiries this afternoon about Lovejoy in the SECCHI HI-1A data, so that's what I'm going to focus on here. Since proving me completely wrong and surviving its brush with the Sun, Lovejoy has re-emerged back into the HI-1 images looking even brighter and bolder than when it went in. It's visible in the HI-1 instruments on both STEREO spacecraft, but STEREO-A gives us the best view simply because it a little closer to the comet. I have prepared a nice movie of the comet which you can download here as a big 90MB Quicktime movie, or a more reasonable 30MB .wmv file. In both cases, but particularly the latter, you are well-advised to right-click and save the movie locally; playing them directly in the web-browser can have all sorts of random consequences! The image opposite is a screen-grab from the movie. It was hard to balance out the beautiful star scene without over-saturating the brightness in the comet. Note that the small planet is Mercury and the big one Jupiter.
I have collected together the FITS images for the past several days, and you can download those in these rather large zip files.
[*]Dec 16 2011, 100MB Zip file
[*]Dec 17 2011, 105MB Zip file
[*]Dec 18 2011, 105MB Zip file
[*]Dec 19 2011, 99MB Zip file
[*]Dec 20 2011, 169MB Zip file
[*]All the frames (.png) from the above movie as a 95MB Zip file
These are the raw data files so you'll need to do some processing to make them pretty. Try, for example, making a single image that is the median or minimum pixel value for all images, and then subtracting that single median/min from each image in the set. That will remove a lot of the haze and the brightness gradient. You can also try shifting each image to co-align the stars and then subtracting them out. If you have the software tools for it, it's tremendous fun!
This will be my last entry again for today but I should be back tomorrow with yet more movies and info!
来源于叶儿山
彗星C/2011 W3 (Lovejoy)按预报在12月16日通过了近日点。作为1970年后首颗在地面上发现的克鲁兹族掠日彗星，Lovejoy彗星在没过近日点前就已经得到相关领域科学家及天文爱好者的关注，甚至有人认为Lovejoy彗星可以复制1965年池谷-关彗星的伟业，能达到-10等以上。在掠日彗星研究领域颇有名望的美国太空署K. Battams博士和约翰霍普金斯大学M. Knight博士则估计其最大亮度在-3到-4等之间，这一估计事后被证明比较准确。然而，由于彗星近日点几乎就在太阳表面，几乎所有人都一致认为Lovejoy彗星将无法在百万度的高温中幸存。
然而，大大出乎所有人意料的是，Lovejoy彗星居然几乎毫发无损地通过了“鬼门关”！美国宇航局、欧洲空间局和日本宇宙航空研究开发机构(JAXA)在轨运行的SOHO、STEREO、SDO、PROBA和Hinode探测器都记录到了Lovejoy彗星优雅地全身而退的壮丽景象。如同科学史上每一个出乎意料的发现一样，Lovejoy彗星顽强地与太阳“对视”的景象在地球上紧盯着电脑屏幕的人们之中引起了轰动！在科学家们宣布的“死亡时间”过后6个小时，抛去旧尾巴的Lovejoy彗星神奇地再度在屏幕上出现，并迅速长出一条更加漂亮的新尾巴。K. Battams博士说自己原先的预测是个“极大的错误”之后说，“这不仅仅是有新闻价值，也不仅仅是十分有趣，这是完全彻底的不可思议！”著名天文学家J. Bortle也评价道，“我深信我们正在目睹的是彗星史上最不寻常的一幕。”
我处理和收集了部分由太空探测器拍摄到的壮观画面，在这里公布。由于探测器和地球间数据传输问题，预计过几日原始数据传输完整之后还可以有更多画面公布。这几天南半球已经有许多爱好者拍摄到Lovejoy彗星的长尾在日出前冉冉升起的奇特景象，如果正好有在南半球的朋友，可要好好把握这个机会。估计Lovejoy彗星目前仍有2-3等的亮度，其彗尾长度据报告在15-20度之间。
http://y234.cn/wp-content/uploads/2011/12/Lovejoy_combo_gap-600x450.jpg SOHO探测器AIA304、C2和C3叠加影像，显示Lovejoy彗星即将通过“鬼门关”前的样貌
http://y234.cn/wp-content/uploads/2011/12/lovejoy_c3.gif SOHO探测器LASCO C3照相仪在14日-18日之间的动画，显示Lovejoy彗星涅槃重生的壮观过程，中间的小白圈代表太阳
http://y234.cn/wp-content/uploads/2011/12/lovejoy_c2.gif SOHO探测器LASCO C2照相仪在15-16日间的动画；C2视场比C3要小，可观察更靠近太阳的区域
http://y234.cn/wp-content/uploads/2011/12/euviA_lovejoy_anim-600x624.gif
STEREO/SECCHI COR-1B记录下Lovejoy彗星通过近日点时的壮观景象。STEREO-B和SOHO的位置不太一样，因此直接观察到了Lovejoy彗星“甩尾”的景象，这在彗星史上可是第一次。来源于Sungrazing Comets。
COMET LOVEJOY GETS EVEN BETTER: Sungrazing Comet Lovejoy is so bright that "it can now be seen with the unaided eye for more than an hour before sunrise," reports Colin Legg of Mandurah, Western Australia. This morning, a short exposure with Legg's digital camera was sufficient to reveal the comet's reflection in the waters of the Mandurah Estuary:http://spaceweather.com/images2011/22dec11/reflections_strip.jpg"It was an amazing sight," says Legg. Indeed, Lovejoy appears to be the finest comet since Comet McNaught in 2007.Dawn sightings of Comet Lovejoy are now widespread around the Southern Hemisphere. (The tilt of the comet's orbit does not favor northern sightings.) Many observers are asking about the comet's "double tail." These are the dust and ion tails. The gaseous ion tail is blown almost directly away from the sun by the solar wind, while the heavier, brighter dust tail more closely follows the comet's orbit: diagram. The gap between the two tails can be seen with the naked eye while the sky is still pitch dark ~30 minutes before dawn.The visibility of Comet Lovejoy should continue to improve in the days ahead as the comet moves farther away from the sun. Early-rising sky watchers in the southern hemisphere should be alert for this rare apparition. [finder chart]more images: from Emilio Lepeley of Vicuna, Chile; from Rogerio Marcon of Campinas SP Brasil; from Stephen Chadwick of Himatangi Beach, New Zealand; from Kosma Coronaios of Louis Trichardt, Limpopo Province, South Africa; from Paulo Morales Valdebenito of San Francisco de Mostazal, Chile; from Willian Souza of Sao Paulo, Brazil; from Grahame Kelaher of Perth, Western Australia; from Minoru Yoneto of Queenstown, New Zealand;
信息 来自香港天文学会
Lovejoy 彗星成為今年聖誕的大彗星，可以同2007年的 McNaught 彗星，1997年的 Hale-Bopp 彗星及1965年的池谷 關彗星比美
Credit:Stephen Chadwick
http://images.tvnz.co.nz/tvnz_images/shared/2011/lovejoy_commuter_light_234_n2.jpg
Credit:Noel Munford
http://images.tvnz.co.nz/tvnz_images/shared/2011/lovejoy_dark_sky_234_n2.jpg
Credit:巴西 Fernando Lopes
http://nevoeiro.org/wp-content/uploads/2011/12/IMG_8103p.jpg
Credit:Colin Legg
http://www.iceinspace.com.au/forum/attachment_browse.php?a=105827
信息来源于 香港天文学会
由國際太空站拍攝的 Lovejoy 彗星
Credit:NASA
http://spaceflight.nasa.gov/gallery/images/station/crew-30/hires/iss030e014350.jpg
動畫，須稍為等候，下載完畢才可見完整過程
(地面閃光是地球上雷雨地區閃電現象)
ISS Lovejoy.gif (1.79 MB) 下載次數:0
2 小時前
http://forum.hkas.org.hk/attachments/month_1112/1112230708042ab525dbde92cf.gif
Dec. 22, 2011
http://spaceweather.com/submissions/images/spacer.gif
Location:
http://spaceweather.com/submissions/images/spacer.gif
Mandurah, Western Australia
http://spaceweather.com/submissions/images/spacer.gif
Details:
http://spaceweather.com/submissions/images/spacer.gif
While walking the foreshore of the Mandurah Estuary, I came across an embayment of still water with nice star and comet reflections. The bright light at right is a small town. The comet is now visible for more than an hour naked eye. Amazing sight.
http://spaceweather.com/submissions/images/spacer.gif
http://spaceweather.com/submissions/pics/c/Colin-Legg-Comet-Lovejoy-Reflections_1324535827_med.jpg
http://vimeo.com/34007626
本帖最后由 q零度星系 于 2011-12-23 19:41 编辑
Had a beautiful view of the comet this morning. I took this sequence to try to capture the changing face of the comet as twilight progressed.
Tech details:
Date 21/12/2011 - 3:12:00 -> 4:33:30 AWST
Canon 5D2
Canon 24mm f/1.4 II
Little Bramper - thewhippersnapper.com/LittleBramper/Site/Home.html
Exposure varied from 7s, iso 3200, f/2.5 start to 0.1 s, iso 100, f/2.5 end.
Interval 10 s
http://www.nasa.gov/multimedia/videogallery/index.html?media_id=125774121
http://sungrazer.nrl.navy.mil/images/lovejoy/lovejoy_cor1_tail.jpg
本帖最后由 q零度星系 于 2011-12-24 11:50 编辑
来源于 香港天文学会
澳洲 Lester Barnes 12月23日 拍攝的 Lovejoy 彗星照片
http://spaceweather.com/images2011/23dec11/lovejoyfromearth_strip.jpg
Comet 2011 W3 (Lovejoy)In mid December 2011 Loveyjoy passed the Sun at a distance less than 200 000 km from the solar surface. It was not expected to survive - but it did!
As at December 21 it has been seen in the dawn sky as it emerges from the Sun. It is at present in Scorpius, to the right of Antares, but will rapidly move south and crosses into Ara on December 26. Within a day or two Lovejoy will become a circumpolar object and so will be in southern skies all night by the end of December. It crosses the south pole January 8/9.
Lovejoy may be visible to the unaided eye for the next few days, it should certainly be visible in binoculars. Look to the southeast in the dawn sky, say an hour before sunrise. The tail is almost vertical at this time.
Before the end of December Lovejoy will be in New Zealand skies all night. From about the 28th, following sunset as the sky darkens the comet will be low a little to the east of south. The tail will spread to the left but swing higher later in the evening. The nucleus of the comet will get higher during the following nights.
Chart showing the path of Lovejoy up to 2012 January 10.The chart is a southern hemisphere view orientated for the dawn sky at about 5am.
Stars to magnitude 4.5 are shown with magnitudes labelled for stars brighter than magnitude 3.0.
The circle on the chart represents a field of view 5° in diameter, a fairly typical field of view for binoculars. http://www.rasnz.org.nz/Comets/Graphics/2012Lovejoy.gif
http://cometography.com/lcomets/2011W3_20111221_RA2.jpg
Copyright © 2011 by Rodney Austin (Marsland Hill, New Plymouth, New Zealand) This image was acquired on December 21.65.This was a 20-second exposure using a Canon Kiss DSLR and an 18mm lens.The Moon is to the left and New Plymouth Observatory is to the right.
http://cometography.com/lcomets/2011W3_20111221_ISS1.jpg
Copyright © 2011 by NASA/Dan Burbank (Expedition 30 commander, International Space Station) Comet Lovejoy is visible near EarthÂ’s horizon in this image photographed by NASA astronaut Dan Burbank, Expedition 30 commander, onboard the International Space Station on Dec. 21, 2011.