观星手记
Lulin dating compaign: update on Jan. 31
Jan 31st
I drag myself out of bed again at 4:30 a.m. It's another very clear night, with limiting magnitude around 5.4 (using IMO method -- but this do not mean that tonight is better than last night, since last night I had to use a not-well located reference field as the cirrus block the favourite one). I get the 13-cm refractor out and set it up, but it takes me a little bit longer than last night to see the comet.
With a telescope, the sky quality seems to be slightly better than last night, the faintest star I have been able to see is TYC 6174-464-1 at 12.28 mag, but (26) Proserpina (12.5 mag) is still invisible. Galaxy NGC 5890 (at 12.6 mag) is only 10' away according to the map, unsurprisingly it's not visible, too. Tonight I have much more options on comparasion stars -- but the observation doesn't make me feel exciting. I estimate the total brightness of the comet to be around 7.3 mag using Morris method, with six comparasion stars at mag 6.17-7.97, while the coma diameter to be 7'. The comet's look does not change much except a 30" dense core run out tonight. Tonight's estimate is 0.5 mag fainter than that of last night, I think tonight's one is more reliable since only two comparasion stars were used last night.
Shortly before the astronimical twilight starts, I also give a try on NGC 5892, a galaxy about 3 degrees away at 12.0 mag, but with no luck. Seems its surface brightness is still too dim. I then shift back to Lulin and see it off in the twilight (still barely visible even after the nautical twilight started!).
I'm not sure when would the next dating occur. I'll be away for a three-week tour in the country soon, and the rainy season will begin at Guangzhou before I come back. I'll try if I can spot it with naked-eye when I arrive at Mt. Huangshan in mid Feburary.
Second dating with Lulin
Jan 30th
As Comet Lulin is now approaching the Earth, the questions such as "how is your comet" or "did you take look at your comet" frequently fly into my ears. When replying these questions, I'd love to refer the comet as "my girl", and a standard reply is "no, I haven't date with her since last August". What's more, for a co-activity with Lulin's "heaven" show, I let my hair grow to a record length, and promise to my friends that "I will make it up according to the appearance of Lulin's tails". But actually, up to now, I have no time to make it up, and to be honest, no idea on how to make it up. I used to keep my hair very short. (the "public" reason is that the Lulin's tails are generally not visible yet)
As several cold fronts went over the Pearl River Delta around the Chinese New Year's Day, the air quality had improved to a very remarkable level. On Jan. 27, the Air Pollution Index (API) of Guangzhou's downtown was even down to 14 (while the average API of the downtown area is around 70-80). The Astroweather Panel suggested the sky would be clear in the morning of Jan. 30, so I went to my house at the countryside for a 4-day stay on Jan. 28. The air quality there was even more surprising -- with API lower than 4. Such an excellent air quality is rarely seen in the well-polluted Pearl River Delta area.
When I drag myself out of bed at 4 a.m. in the morning of Jan. 30, the sky did cleared up, although not as that good as Astroweather Panel predicted -- there are still a few cirrus on the sky. I checked the values of a nearby meteorological station, the temperature is 9.8C, not very low yet. So I carried by 80-mm f/5 refractor out. Except the cirrus, the sky is remarkably clear, I estimate the limiting magnitude to be 5.1 with IMO method -- also a record for this observing site. I wait for a few minutes until the cirrus move away from Libra, then point the telescope to the area. I don't bring my laptop out -- I was always very lazy and would not bring my laptop to the telescope, until I admit I'm unable remember the exact location of the target I want to observe. But this time I get a bonus, a fuzzy ball appeared in my view within only half a minute. I went into my bedroom, check the finding map, and confirm it's indeed "my girl".
I moved my biggest telescope -- a 13-cm f/6.4 refractor -- into the observing field. The 13-cm has a much better quality than the 8-cm. I point it to the comet, and try to estimate the comet's brightness using Sidgwick method. I'm not a good visual comet observer, and there are not sufficient comparasion stars around the area, so the observasion may be of some errors. The first estimate is 6.1 mag, but shortly after that I find out the comet is just occulting with a 10.72 mag star (TYC 6175-46-1), so I wait until it moves away from the star and make a second estimate. The final estimate is 6.7 mag with coma diameter to be 7'. The comet is slightly elongated over the ecliptic. After observed the comet, I make some attempts to see how deep I can go. A 12.16 mag star (TYC 6175-765-1) is visible, although not easily, but an asteroid nearby (26 Proserpina, around 12.5 mag) can not be seen, so the limiting magnitude for the 13-cm refractor at this night should be around 12.2 mag.
The twilight appears and marks the end of observing, I watch a beautiful sunrise (I always get excited about sunrises and sunsets!) at the observing field before go back to sleep. The visibility is also very remarkable today -- the 50-km away Mount Apoliu is clearly visible in twilight over a small patch of "cloud-sea".
Comet McNaught: Image of pre-discovery
Jan 10th
I just know that I had a near-miss to my second comet discovery in late 2007, since the Minor Planet Center has just reported the identification made by Mike Meyer, that three observations I made in late 2007 was actually linked with a recent discovered comet, but that's largely caused by bad luck instead of careless review of candidates -- see above.
This tiny snow ball, is now recognized as Comet McNaught, designed P/2008 Y3, it was found at the New Year's Eve of 2009 by Australian astronomer Rob McNaught. I had received a warm welcome by Rob during my visit to the Siding Spring Observatory, and he gave me a beautiful post of the Great Daylight Comet he found (C/2006 P1), as well as his signature and words, "May you discovered more comets!" However, he has taken one from my hand Oops, Rob, I'm not blaming you -- because it was still two months before you wrote the words when I detected it, we were both not aware of such an occasion being presenting.
The self-developed reduction pipeline did detected the faint dot although it was then running through the milky way, and was "encounted" with a bright star (the encounted image was neglected when making the image you see). As the comet was then about 3.94 a.u. from the Earth (about 590 million kilometers), the cometary feature was rather weak, so it's not surprising for me to count it as an asteroid at that time. Anyway, congratulations for your 45th comet, Rob! (Yes, Rob is the most profit individual discoverer in the history by far)
Comet C/2007 N3 (Lulin) on Jan. 5
Jan 8th
[Images Removed]
A total of nine images of Comet Lulin were taken by the Lulin 0.41-m reflector over the night of Jan. 5, and I used every of them to process three impressive images as you have seen above. The first one is a color image, combined from one Blue-band image, one Visual-band image and seven averaged Red-band image, a low-pass FFT (Fast Fourier Transfer) filter was applied to let more details run out. The second image was averaged from seven Red-band image, a suprising ion-tail to the left, at a length of about 15-20' (the width of the image is 38'), was turned up after the align-and-stack method. Low-pass FFT was applied as well. The third image was processed by the Larson-Sekanina Rotational Gradient method, and it enabled us to see the near-nucleis jets of the comet. At least nine jets were counted besides the ion and the dust tails, and this feature does not be presented on the Jan. 1 and Jan. 2 images. This might be caused by the decreasing distance from the comet to the Earth as well as the sun. All the images were reduced to 600x600 pixel to match the size of my blog, the origin size images can be viewed below.
Update on Jan. 14: Since a complaint about the publication of their images from Lulin Observatory was filed to me yesterday, I have removed all the images about Comet Lulin appeared on my blog, of those taken by the 0.41-m reflector but NOT in the course of Lulin Sky Survey. My profuse apologizes go to Dr. Z. Y. Lin, who is considered to be the legal user of the data; and to those who are involved, including those who had got my permission to use these images earlier. I'll continuously monitoring the comet and post anything new on my blog, while ensuring only data from Lulin Sky Survey (the program I'm now responsible for) to be publicazed in any cases when the material is involved with Lulin Observatory.
Multi-tails of Comet C/2007 N3 Lulin
Jan 5th
[Image Removed]
Continuing my post on Jan. 2, one more image of Comet Lulin is hereby publicized. A total of five R-band images, taken by the 0.41-m Lulin reflector on Jan. 2/3, were aligned and combined to create this image, a "bold" dust tail (anti-tail) plus three medium-to-weak ion-tail can be seen with ease. "We are observing comet C/2007 N3 Lulin 'edge-on' with incredible fortune!" Michael Mattiazzo (by the way -- he is among the astronomers I had visited during my trip to Australia) remarks, as the orbital inclination of Comet Lulin is about 178 degrees -- virtually in the same orbital plane (but moving in the opposite direction) as the Earth. Benefically from this situation, the brightness of the comet will be enhanced since we are observing the comet and its dust tail "altogether". More materials will appeared on Yeiht (this site) when they are ready.
A most recent photo of Comet Lulin
Jan 2nd
[Image Removed]
After discovered by Chi Sheng and me on July 11, 2007, Comet C/2007 N3 (Lulin) was brightening gradually as it approach to the sun. Now it is around 7 mag, shining on the east at dawn. If the prediction is right, it will be around 4 mag on late Feburary, marked as the brightest comet in the year (among the so far known).
This image was taken on the night of Jan. 1 by the 0.41-m reflector at Lulin Observatory (the instrument that used to discover the comet), a total of three images under Johnson B/V and Cousins R were later aligned and combined by myself, to create a "color" image. Two tails can be seen, as the one to right (the dust tail) is an anti-tail, caused by our observing angle. The streak on the left is a man-made satellite. The background stars look strange as the comet moves when taking the series of images.
As the discoverer, I'm feeling lucky to see the comet which I detect it first among the human beings, is now on a significant brightness. However, at the same time, I'm also reminded with such a story -- a teacher once asked his student, "which island is the biggest island before the discovery of Australia?" "Greenland." Some replied. "It's still Australia. Whether our human beings discovered it or not does not do anything to the fact that it's the biggest island on the Earth." I think, I was, simply, spotted the comet before anyone else, and that's all. I was just lucky. Anyway, I'll observe the comet in the next couple of weeks exactly -- maybe, just with a little bit extra excitation -- as others may do. Happy observing in the International Year of Astronomy, guys!
风云1号D星拍摄的8月1日日全食月影
Dec 26th
为了准备奖学金答辩,23日跑去卫星站折腾了半个晚上,正好翻出风云1号D星拍摄的日全食时的月球影子,处理了一下发上来给大家欣赏。感谢希希助理的协助。
12月13/14日双子座流星雨观测
Dec 14th
壮观的双子座流星雨很少会让人产生“退票”的念头。所以,尽管皓月当空,我还是安排了观测计划。
晴天钟的预测还算准确,13日早晨阴天,随后逐渐放晴。但冷空气并未使空气质量立即改善,13日晚月出前极限星等仅为3.5等左右;月亮一出来,天空简直就是惨不忍睹,连1等星都很勉强,只好等月亮过中天以后再开始观测。不过,在我被迫耐心等待的时候,双子似乎倒十分兴奋,我0点和1点多两次出去查看天气,各呆了不到2分钟,结果就看到了3颗流星,还有一颗是曳过大半个夜空的火流星。
浪费了大半个晚上以后,14日2:41,观测总算开始了。由于北风的不断加强,低空大气也好转了不少,利用9号天区测定的极限星等约为2.23等—— 我承认这是个120%可以让人睡觉的数值。但双子座流星雨,一年等一回,所以我还是披上冲锋衣,把行军床挪到天台上。温度计显示气温约为15摄氏度,但北风却异常大,阵风甚至可达强风级别,吹得我还没躺下来就瑟瑟发抖(那件冲锋衣可是去北疆的时候穿的)。第6年看双子,依然有惊喜:躺下来还不到1分钟,一颗约-4等的火流星就表示欢迎(其实这么烂的天,看到的也只能是火流星了),接下来9分钟内又出现了2颗流星(注意,是这么烂的天里头的数字)。双子这块金字招牌续写传奇。
比较糟糕的是我很快一边发抖一边犯困,眼皮开始不听使唤。想起虾说在实验室通宵弄细胞(还是别的什么?反正我也不懂),要找个人去陪着说说话,还说实验室的空调只有吹风和除湿两档,云云。哎!我这个实验可好得很,不仅孤军奋战,还可以“享受”老天的天然大空调,咔咔。为了保持清醒,我不得不在行军床上扭成各种姿势。我想,从第三者的视角来看,明亮月光下的一个扭来扭去的东西一定很诡异吧。
最大的惊喜是在3:10,一颗约-6等的火流星在狮子座炸开,用一个土得不能再土的比喻,“像闪电一样”。我不禁欢呼致敬,因为至少一年没见过这么亮的流星了。
到3:27,困得犯糊涂了,决定暂时中止观测,去睡上40分钟再继续。于是跑回室内,一边听着北风呜呜叫一边打盹。到了4:10左右,我熟练的把自己从床上拽起来(按掉闹钟继续睡?这样可就是严重事故了—— 假如你成百次地把自己从床上拽起来过的话),结果发现起了很薄的云。既伤心又高兴,伤心是因为没法观测了,高兴是因为总算有个理由让自己不用像个木乃伊一样在外面发抖了。每隔15分钟出外查看一下天气,一直有薄云,便把给国际流星组织的报告填好:
// Header section
night 2008-12-13/14
begin 2008-12-13 1841
end 2008-12-13 1927
observer "Quanzhi" "Ye"
location 113 30 00 E, 23 28 30 N
site "A'Lazyboy Observatory, Guangzhou" "China"
reporter "tom6740[at]gmail.com"// Shower section
shower GEM 112 +33
shower SPO// Number section
// Interval RA Dec Teff F Lm GEM SPO
period 1841-1927 150 +20 0.660 1.14 2.23 C 9 C 2// Magnitude section
// Show Interval -6 -5 -4 -3 -2 -1 +0 +1 +2 +3 +4 +5 +6 +7 Tot
distribution GEM 1841-1927 1.0 0.0 1.0 2.0 1.0 1.0 1.0 2.0 0.0 0.0 0.0 0.0 0.0 0.0 9.0// Personal comments
Bright moonlight and haze seriously reduced the sky quality. The second period began at 20:17 UT but was terminated after a few minutes by the cirrus.
插一句:考完“也不过如此”的AW以后,写起英文来,真是下笔如有神啦,哈哈。
祝各位早安。
起床后补记的后记:尽管这一次是在乡村地带观测,却经受了有史以来最糟糕的一次双子座流星雨的观测环境—— 2003年在市中心观测,也录得约3.5的极限星等,3个夜晚累计观测约7小时,流星计数逾200颗。半个月以后还有全年三大流星雨之一的象限仪,让我们看看老天又有什么展现吧。
11月29/30日观星笔记
Nov 30th
主力装备13公分折射镜拉至新台址以后第二次执行正规观测,我现在也甚少认真地用肉眼去看星空了。本来想以起雾为借口缩在暖和的房间里,却遇到了小石头,她正要带领一班人马把15公分反射扛到珠海校区的高尔夫球场观测,于是“观测势力”又占了上风。最终我还是穿上冲锋衣,把大小家伙都拉到了露台上。
由于前几天冷锋过境,广州出现了连续的高透明度晴朗天气,测定极限星等介于4.9-5.2等之间,对于郊区来说已算非常不错。具体观测项目简述如下:
- M42:测试用,但印象很深刻,往M43方向的凹状结构明显。
- IC 434:本想找马头星云,无奈天气条件远未达标,因此最终仅用侧视法感觉到了IC 434的存在。即使将zeta星移到视场外,剩余的亮星仍有不小的干扰。NGC 2024倒是比较容易看到。
- M78:从来都没留下太深刻的印象,一团东西而已,但对于测定观测条件还是挺有帮助的。这次的M78大约比枣核略大(用的是蔡元生赠的18毫米ED目镜),可见观测条件还是不错的。
- NGC 2237, 39, 64:因为是在银河里,所以找引导星相当麻烦,对双子座xi都对了半天,哎,太久不观测就是这么笨拙。37和39都是弥散星云,只能感觉到星点好像目镜结露一样略有朦胧,看不出什么细节。不过在银河里面漫步的感觉还是非常爽的。
- M44:因为上面的目标都很认真地去观测,结果看完以后发现巨蟹座已经升得老高了,就无聊一把,去观测已经看过无数遍的M44(其实M天体大部分都看了无数遍……),测了一下望远镜里的极限星等:10.2等星可以用直视法轻松看到,如果用侧视+闪视法专心观测,最暗可以看到12.2等的星。想起做测光的时候,12等以上的星基本都会亮得溢出,现在看到了却这么激动,哎,物是人非嘛。
- M81, 82, NGC 3077:和小石头聊的时候谈到NGC,她说只记得俩:1981和5139。结果我居然把1981记成了M81,把5139记成了M51!哎,我当时就说了句:“我可以go了。”想当初,成打成打的NGC倒背如流,可现在呢?第一个反应是去查GSC…… ok,正好看到大熊座探出了脑袋,就把望远镜瞄准大熊的脑袋。M81虽然周围没什么亮星,但要指向它可实在是件轻松事,我几乎半闭着眼睛就找到了它。看这些星系的时候总是不得不逼着自己发些感慨。为什么?M81距离我们1200万光年,这个距离之大实在令我们无法想象(其实缩小100万倍,也无法想象……)。看着星系那点点幽光,总让人觉得孤独,凄凉。M82也在同一视场内,但3077就愣是看不到,可能因为地平高度不太高。
- 土星,土卫五,土卫六:发现狮子出来了,就打狮子脚下的土星。很意外,这一次竟然观测到了土卫五尼亚,我以前只见过土星最大的卫星—— 土卫六泰坦。别说M81了,就算是土星也够遥远的。
- M1:打了个哈欠,觉得挺困了,于是打算最后打几个目标。小石头说她下定决心要找到M1。M1我看可以算是最简单的M天体之一了,半分钟左右就逮住。不过有趣的不是M1,而是恰好经过M1附近的一颗人造卫星,大概9等左右。我饶有兴致的跟着它逛了小半个天空,又遇到了各种各样的星星。哈,有点像爱丽丝漫游奇境记,对吧?
- M45:既然到了金牛座,就瞟两眼七姐妹吧。
- 对着天空发呆等流星:后半夜,灯光少了些,天空也更透彻了。无论你从哪个角度看过去,都能毫不费力的辨认出银河的位置,而不像大多数时候那样,必须要先认星,确定银河的位置,然后才能艰难地分辨出来。广州的地盘上还能这么轻松的看到银河,不错,当然在市区轻松看到银河的可能性仍然比市区下雪的可能性还要低。等了半天没看到流星,倒是刚才看望远镜的时候看到几颗偷偷摸摸的从视场里溜过去的。
- M42:善始善终,最后一个也看看它吧。让我大吃一惊的是,我竟然看到了一些更为细致的结构,比如M43反方向的那一段精致的暗切边,这也是以前从未看到过的。倒不是没遇到过好的观测条件,而是好的观测条件与大的望远镜同时存在的机会还是很小的。想起第一次看到M42时的情景,早已经是11年前的往事了。对着M42发了一阵呆,收工。
穿上冲锋衣仍然发抖,就把温度表拿出来一量,约莫6摄氏度,看来晴天钟预测不赖。看着满天繁星,又不想收工了,只好每收一个零件就抬头望几眼。观星就是这么一件矛盾的怪事:没开始的时候不想出来,想方设法给自己列不值得观测的理由;要结束了又不想回去,走一步停一步仰头望望,等待老天爷又秀个什么东西出来。咔咔。
Another new comet confirmation: D1D001
Oct 8th
Just confirmed another new comet, discovered by COD 661 yesterday at magnitude ~17R. Very obvious cometary appearance. Congratulations to the discoverer!
Observation and addtional report to CBAT/MPC as follows:
COD D35
CON Q.-z. Ye, Department of Atmosphere Science, Sun Yat-sen University,
CON 132 Waihuan-Dong Rd., Guangzhou, China
CON [[email protected]]
OBS Q.-z. Ye
TEL 0.41-m Ritchey-Chretien + CCD
NET UCAC-2
ACK LUSS observations
AC2 [email protected]
COM Stacked all three images revealed a very diffuse coma at 10\", plus a very
COM faint, fan-alike wide tail towards p.a. 210deg-315deg. Magnitude measurement
COM in T. The image could be retrieved at
COM http://yeiht.y234.cn/wordpress/wp-content/uploads/2008/10/d1d001.png
D1D001 C2008 10 08.61167 07 29 40.01 +81 01 20.5 17.3 R D35
D1D001 C2008 10 08.61250 07 29 40.15 +81 01 21.5 17.3 R D35
D1D001 C2008 10 08.61333 07 29 40.20 +81 01 20.8 17.2 R D35
----- end -----
最新评论 Recent Comments