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Singapore Sky, My Night
Safari (Observing the night sky in Singapore) |
Singapore is a tropical, beautiful garden city. Our streets are lined with powerful Halogen lamps and some of our sky-scrapers are lit throughout the night. Our lives seem to be concentrated only on the two-dimension build-up areas that we are accustomed to.
What about the sky? What can you see when you peer into the not-so-dark sky at night?
Occasionally, we see one or two lonely stars shimmering aimlessly in the sky, showing themselves so painfully through the gaps of our HDB blocks. We wonder why they are there for that brief mysterious moment. But the need to go back home and take refuge after a hard day's work seems to be more pressing. Let the stars stay where they are and give us some peace of mind!
As far as I can remember, the first time I heard about stars was during my National Service. In one of the navigation course, we learnt that the stars could guide us when we were lost. That was the first time I heard about Orion, the hunter constellation that rose right from the East and set in the West, stayed around the zenith early at night in February and March. Its "sword" always pointed to the North through the center of the "belt". I did not understand its movement at that moment, sometime I found them, sometime I did not. That made me wonder how come human being could think of using such a lousy means of navigation.
I started to be interested in the sky quite by accident. I wanted to buy a microscope because I was interested in small little things that I could not see with naked eyes. I went to a toy store and got a microscope with a mind wobbling magnification of 750. I thought it was fantastic for that meager price I paid. But I was very disappointed the first moment I tried it. It was really a toy and you just could not do anything serious with it. I went to see one of my colleague friends who happened to be a amateur astronomer. I got a real microscope from an optical shop that he recommended. I had good time with that new microscope; I made specimens of my three children's hair and compared them under the microscope. The fine detail of hair revealed very well and it was interesting to note the differences between young and old hair.
After I bought the microscope, my friend declare "solemnly" to me, "The next thing you should buy is a telescope, that is the only real optical instrument!". He gave me a concise guide on astronomy, Peterson first guide to astronomy. I borrowed a pairs of binocular from him as well. That was in November. The night was clear. After putting our children to bed, I and my wife spent a few hours in our front yard, shading our eyes from street lamps with our palms, peering into the sky looking for stars. Being good at orientation and reading the planisphere, I point somewhere north of the zenith and instructed confidently to my wife, "there, you will find a group of six stars, go and find them." "I have already seen it." came the reply from my wife. I was surprised that she got a much better eyesight than me and she could make out six stars in the Pleiades Cluster with naked eyes. And that burst my ego! So I asked her to find some more "difficult" stars; I was looking in the north and trying to find the Cassiopeia. It lay pretty low in the sky and the glow from the nearby town made it even more difficult to locate. "You should see a M down there." Thinking that my wife would have hard time finding it, I looked more diligently in that direction and tried to beat my wife to it. I was completely "demolished" when my wife traced the M in no time. Under this "healthy" competition, we managed to locate 8 constellations during that two hours rendezvous with the sky.
That was when I decided to buy a telescope.
I bought a 3 inch spotter scope. That night and the few nights that followed, I observed Venus, Jupiter and its four moon, Saturn, moon, double clusters at Perseus and many more that I could not remember. For a beginner like me, that was overwhelming and awe-inspiring. In order to see the whole sky, sometime I had to venture out of my house and set my telescope on the pavement. That attracted some of my neighbors, and suddenly, I became an experienced amateur astronomer explaining the intriguing aspects of planets and stars to them. One of my neighbors that I have no acquaintance before even declared "There is no need to bring my kids to Science Center anymore."
That was when I decided to buy a bigger telescope.
I traded in my 3 inch
telescope for a 5 inch. That was barely two weeks after I bought my first scope. I also
bought a motorized equatorial mount that cost more than my scope. It compensated for the
rotation of the earth so that I could observe the stars without the need to
"chase" after them. For visual observation purpose, I could do an approximate
polar alignment of the telescope with just a compass and a spirit level. It took less than
one minute and allowed me to observe leisurely for 5 to 10 minutes before the stars went
out of the view of the eye-piece. It was also good for my family; all of us could take
turn to observe, held interesting discussion without having to bother with any adjustment.
I realized that star gazing could be an interesting family gathering.
While
I was aligning the finder scope and testing my new telescope during day time, I came
across this beautiful bee-eater perching on the TV aerial far away on the roof top of my
neighbor. It stayed there for a long time, just long enough for me to sketch it down by
looking through the telescope. Singapore is a place where you can find a lot of birds
right in the town areas. It is not difficult to identify 20 species in a few days if
you go bird watching around your housing estate. If you are a bird watcher as well, the
telescope and binoculars you have for star gazing will never lie idling in your
de-humidifier during day time.
In late December (1997), the star Procyon was just starting to rise from the rooftop of my neighbors. It made a perfect equilateral triangle with Betelgeuse and Sirius, the brightest star in our sky.
When the sky was clear, I liked to scan the milky way and star clusters with the help of my 7X50 binoculars. Although we could not see the milky way with our naked eyes, it was wonderful to see so many faint stars forming the backdrop of brighter stars that made up the shapes of the constellations. The double clusters at Perseus looked like two blurred stars. It looked dramatic in my telescope after I added a reducer to it so that I could see both of them together. The bright stars of Cancer were hardly discernible, but its Beehive cluster filled the full view of my 6° binoculars. It was one of the most beautiful cluster you could see in the early evening of February. Another easy-to-find and beautiful cluster located right in Major Canis was M41; It looked like a blurred spot in the binoculars but revealed itself mystically well in the telescope. There were another 3 small open clusters in Auriga. It took some practice in star hopping before one could spot all those clusters.
When the sky was clear in February (1998), I stayed late until midnight. At midnight, I could scan the sky from the zenith to the South; I could find Orion, Major Canis, Puppies, Vela, Carina and Crux in that order. The rich star field along the way was really something not to be missed. I discovered how useful binoculars were in locating faint stars of a constellation and in observing clusters. Most of the star clusters looked more impressive in binoculars than in small-view-angle telescope.
I stayed awake the whole night for 3 times in February. I waited until Vega rose from North East and Venus rose from the East. Because of its low altitude and the glow from neighboring town, Vega was not impressive. Venus had changed from an evening star in December (1997) to morning star in February (1998). I had always had an eerie feeling when I first started observing Venus because of its brightness. But the more I looked at it, the more I loved its crystal clear sparkles. Sometimes when the sky was clear, I could still see it at 7 o'clock in the morning. At 4 o'clock when the Scorpius was in full view, it looked splendid. The open cluster M6, M7 and others around Scorpius were beautiful. Another wonderful thing that could be seen earlier was the Omega Centauri, a globular cluster as big as a moon. Unfortunately, we could not see it with naked eyes in Singapore due to light pollution. It looked like a ball of cotton wool in the binoculars but I could not resolved it with my small telescope. Sparkling beside one of the brightest stars of the Crux was the cluster known as Jewel Box. It looked like a triangle in the binocular but appeared beautifully like a lit Christmas tree in the telescope.
Visual enjoyment was one of the reasons I looked at the sky so often. Some people even said that the sky provided the best show that had ever been offered on earth. I didn't think that was an exaggeration. But not being able to see nebulae (except the brightest part of M42) and galaxies was a serious limitation for me who could only view the sky from my light polluted front yard.
That was when I bought a CCD camera in the hope of improving visual observation.
I was pretty excited when I received my color CCD camera form UK after 2 month of waiting. After one night of trying, I started to take pictures of the moon the following night. It happened to be a half moon. I trained my telescope at the moon and took more than 20 pictures at one go. Because the exposure time was very short, less that a few hundredth of a seconds; I did not need to polar align the telescope. But I did not have any accessory (such as flip mirror) required for CCD imaging. I did the way that most experienced amateurs discouraged: framing the picture with an eyepiece and than replacing it with the CCD. There was a lot of trial and error and pretty frustrating at times.
I e-mailed one of the moon pictures to
the inventor of the CCD camera I bought. He was very kind to advice me on the steps of
image processing and commented that the pictures were well taken for a beginner. What an
encouragement! Every night since then, when the sky was clear, I lugged my telescope with
a heavy equatorial mount, set up my desk top computer in my front yard garden and started
to take pictures. I started with easy targets first: the naked eye nebulae M42 and star
clusters.
It was then I realized how important polar alignment and accuracy of equatorial mount were. I used star drifting method for the alignment and I could take picture with 3 to 4 minute exposure unguided. The periodic error revealed itself when I tried to take picture with exposure longer than that. I also saw the merit of having a CCD for auto-guiding purpose. It would reduce a lot of set-up time and allow you to get into action very fast. That might be the new telescope system I should upgrade to.
My first picture of M42 was surprising,
it was blue around the trapezium. I expected to see only red as I thought it was an
emission nebula. My astronomer friend told me that it was due to oxygen and scientists
were still trying to understand its existence. I was disappointed that 3 minute exposure
could only reveal the brightest part of the nebula and the whole extent could not be seen.
I started to doubt if I could capture images of other nebulae and galaxies which were much
fainter than M42.
The
images of Betelgeuse and Rigel were interesting: their characteristic color of orange and
blue respectively showed very well in the over exposed pictures. I was pleasantly
surprised to see so many faint stars accompanied them. These stars could only be revealed
in CCD pictures but can never be seen with my small telescope.
The CCD picture of Omega Centauri was
fabulous. The blurred round "cotton wool" in my small telescope resolved itself
into hundreds of stars. I realized that CCD camera could be a useful visual aid. It could
show you something in minutes that could not be seen in the eyepiece due to small aperture
of the telescope or light pollution.
In order to make my picture taking sessions easier and less tedious, I mail-ordered a flip mirror from USA. I could fix the eyepiece and CCD camera together and that provided a great deal of flexibility; I could exchange eyepieces to view the sky at different magnifications and field of view. When I needed to polar align or frame the objects, I could also use an appropriate eyepiece (with illuminated cross lines) without touching the CCD camera that had already been fixed and focused. I bought a note-book computer as well to replace my desk-top. It made the electrical connection much simpler.
My ultimate aim was to hunt down galaxies, but the sky was not with me; it was cloudy and hazy most of the time due to the forest fire in Indonesia. Star hopping was difficult as I could not see faint stars. Locating galaxies was all the more difficult as most of them were situated far away from bright stars. At last, after a few nights' trying, I managed to get some blurred patches on my computer screen; that were M65, M66 and M96 in Leo constellation. I was elated!
Although the pictures of the galaxies were bad and "noisy",
I was very satisfied because that proved to me even in light polluted Singapore, we could
see galaxies. The pictures were taken in very adverse conditions; the sky was hazy, the
whole sickle asterism was barely visible with naked eyes and the miserable Antares at 15
degree altitude looked like a star of magnitude 4. In addition to all these, the
integration time of CCD could not go beyond 3 minutes as the equatorial mount could not be
guided. I believed that with bigger telescope and longer integration time, the beautiful
whirling arms of the galaxies could be visible.
The following night, I adjusted the
equatorial mount with more care and patience, I went for 5 minutes integration time. The
Blackeye Galaxy looked beautiful. Its features (including the dark lane, arm and bright
nucleus) showed very well in the picture.
A week later, the sky was still as hazy
as before. The horizon was visibly whitish. I captured this Sombrero galaxy near the
zenith. According to Peterson field guides on stars and planets, the dark lane of dust
could only be detected by medium size telescope under good observing condition. But thank
to CCD, I could even view it under hazy and heavily light polluted environment with a
small telescope. CCD had really made visual astronomy possible in the cities.
These are the
Whirlpool Galaxy and the Pinwheel Galaxy that I have captured a few days later. In the
months of April and May, we were pampered with lot of galaxies in the eastern sky. From my
front yard, I could only see the eastern sky and the western sky was blocked by houses.
Anything that passed the meridian would disappear from my view in half an hour's time. I
usually trained the scope at the galaxies while they were rising from the east and took
pictures when they were near the meridian in order to reduce noise due to skyglow. It was
sometimes very pressurizing when the object was going to disappear from my sight but I was
still not ready to take its picture.
I could only see half or 3/4 length of the arms of the galaxies that I captured with my CCD and telescope (f/6.3). I normally took about 5 pictures of 5 minute exposure and then combined them together to obtain a better picture. Although 5 minute exposure was considered pretty long for CCD, the clarity and skyglow of Singapore sky made the pictures far from perfect. From the histogram of the pictures, I deduced that the CCD would still not be saturated even if a single exposure was to be extended to 15 minutes. That promised good quality pictures if I could upgrade my equatorial mount and made it guide-able, either by another guiding scope or by a CCD autoguider.
The June-July sky was beautiful. For us
who observed at the equator, we were very fortunate to be able to see the full majestic
Scorpius rising from south east east accompanied by the tea pot asterism. When I faced the
east, AquiIa was right in front. I could see Sagittarius and Scorpius on the right, Cygnus
and Lyra on the left. I took this picture of Ring nebula in Lyra when it was pretty low at
about 30 degree. I was once again amazed that I could capture this planetary nebula as the
sky was very bright due to a nearby town situated in that direction.
In August
(1998), the sky was pretty capricious. It could be very warm and sunny in the day time and
cloudy at night. Most of the time, the sky was covered. The two sparkling gas planets
Jupiter and Saturn could both be seen before mid-night in the east. I was always
fascinated by the lines on Jupiter and its 4
moons that festooned so orderly in a straight line. It was also interesting to look
for Saturn's moons that scattered around it. Although these two giant planets appeared
only as white color disks in the telescope, they had never failed to impress me every time
I looked at them.
(12/1997-2/1999)
