Nova Delphini 2013

Okay, I gotta agree sometimes Facebook does provide useful news when it comes to niche interests. Recently an acquaintance from the astronomical society posted a star-map and prompt his readers to observe that particular patch in the night sky with a binocular or record it with a DSLR looking for the creation of a "new star".

It was a transient astronomical event called "nova" occurring within the border of constellation Delphinus (The Dolphin). To a light polluted sky, I have to admit it is quite difficult to pin down this constellation (hence its obscurity) but luckily the Dolphin was surrounded by three bright stars (an asterism astronomers called "the Summer Triangle" bounded by Deneb, Altair and Vega) and if we get the triangle in our viewfinder we are then able to capture the Dolphin and its associated new object.

My attempt in capturing Nova Delphini 2013

Initially designated PNV J20233073+2046041, Koichi Itagaki discovered this new event on the 14th of August, 2013 in Japan. When he first saw it with instruments, it was a dot in the sky not even visible to human eye glowing at magnitude 6.8. Barely days after discovery, the object now called "Nova Delphini 2013" is shining brighter at magnitude 4.5 on 16th of August. Now, magnitude 4.5 is bright enough for our eyes to perceive without optical aids but we need to get to dark observation sites; for the convenience of suburban dwellers, a small telescope or binocular would be enough to reveal this nova - provided we can find it around the Summer Triangle.  

My attempt on wide-angle higher magnification (f = 68mm). High ISO to compensate star tracking.  

At the time of my observation, photographic evaluation shows it was glowing bright yellow, spectroscopic data confirmed hydrogen gas present around the "new star" thus confirming a thermonuclear starburst from a nova. 

Novae are interesting evolutionary features in a binary star systems. It is one of the eventual outcome of two "average sized" stars gravitationally "locked" together much like two ice-skaters swiveling around each other tethered by a rope. Simply put, the sudden brightening of a star called "nova" is a beautiful process involving gravity and explosive nuclear fusion reaction in binary systems. I found a comprehensive lecture on the evolution of binary systems here, it should cover the reason for the occurrence of novae and also type Ia supernovae.

In the coming few weeks, I am interested to take another shot of this object under same photographic settings and compare its relative brightness to its surrounding stars. Finding this object with a telescope will prove to be challenging due to its small field-of-view, but darn my star-trackker was out of service (thanks to unmatching screws) just when I need it. Pfft. 

Sunspot 1777: Webcam Prime Focus at f/8

Since I have moved to this new place after graduation I haven't been using my webcam for prime imaging. However, because of this attempt with my new telescope I realized a few problems (some was the same as previous) and it should be addressed as soon as possible. 

1. [similar problem with my 3" Newtonian] The CMOS sensor is too small to capture the focal spot of the 4.5" reflector so the image appears highly magnified and thus prone to fast image drift causing motion artifacts to photographs. Immediate consequence of using this webcam shows the mount for this telescope system unsuitable - it shouldn't be an alt-azi mount.
2. Unlike the previous solar filtering technique (the previous method was much unsafe and the glass filters are prone to overheating), the images were taken with a ND glass filter located on a mask that was fit to my telescope aperture. It has a diameter much smaller than my scope's primary mirror and hence limit the effective aperture size and hence angular resolution. 
3. Ahh. the plague of dusts finally comes. It appears as streaks of disk shaped blurness in fixed location of the sensor. Luckily, it is easily detected (the large ones) and after taking all the photos, I cleaned it up with a few gentle puffs from my blower. White field test shows much reduced "drifters" so it should be cleaned for now.

So, out of 33 photographs, I selected the best in sharpness (least atmospheric disturbance) and processed it with Photoshop for detail enhancement [picture above]. The sunspot was obviously my target but with its angular size, it was quite difficult to pin down with an alt-azi mount. Anyway, I cannot tell if the speckles on the surface comes from noise or they are actual surface granulation of the sun but good thing was that penumbra of 1777 can be clearly seen. My last attempt of solar imaging was difficult to distinguish the shades from the umbra but then again, webcam prime imaging wasn't possible before without proper filtering technique.

So we have this magnified image but it failed resolve details of the penumbral filaments either due to the limited field of view coupled with flimsy mount or my telescope (actual) aperture cannot provide me enough angular resolution. I'll try with a larger sunspot next time. 

First Attempt of Recording Lunar Halo

Ah.. the beauty of halos. I remember asking myself when I was much younger what was that big bright circle thing in the night sky which always appears to encircle the glorious full moon. Well, now although the natural mystery has been largely solved and understood (as the mechanism for this phenomenon is similar to the formation of rainbows), it is still interesting to whip out my camera and try if I can pack this occasional nature's wonder into a retrievable memory.

So I used my Nikon D5000, took 3 isolated photographs of the event which later I found two shows clearer profile of the spectral dispersion. The clearest photo was taken on May 25 at ISO400, 18mm, f4 and 2 second exposure time showing clear spectral dispersion around the lunar disc. Under this exposure, Scorpio's eye, Antares, appears as a bright dot at approximately 8 o'clock direction of the picture on top. The picture was taken as JPEG (as I originally intend to do a stop-motion video, not aesthetic photography) is then level adjusted, increased in overall saturation for spectral dispersion visibility and increase selective channel of colour to make the blue sky appear more natural.

Now, it is important that the large halo around the moon is formed by refraction and reflection of moonlight upon tiny ice crystals or supercooled water aerosols in the high-skies (by floating cirrocumulus in our case), in some cases when the dispersing particulates are in the right size and geometry, a large spectral dispersed (of rainbow colours) halo can be seen which in our case, doesn't shows perhaps due to incomplete refraction or probably just simply not resolved under my camera setting.

The second photo shows an interesting spectral dispersion in a better spatial profile which its formation is puzzles me. Its vicinity so close to the moon suggest a phenomena of optical diffraction? Anyway, the image was cropped from a 18mm (wide field) photograph, level adjusted to enhance contrast, increased overall saturation to bring up visibility of the spectral dispersion and lastly, selectively adjusted the yellow channel to approximate natural colour of night sky.

Other than these two featured images (the third was bad and omitted) I have taken a series of photographs using a function called "interval shooting" with my camera. Using ISO400, 18mm, f4 and 1.6 second exposure time, the interval cycle was 10 seconds and I have took 72 photographs of the moon without tracking. The images were not post-edited and they were copied into two groups where one was directly stitched into a stop-motion film and another after cropping out the rainbow-ed ring around the moon from the rest of the photo, are then made into stop-motion video using the same method.

So from the short video above, we see a time-resolved evolution of the halo. Before any analysis, it is obvious that video like this shows how precious each photo-worthy moment are to astrophotographers as a good photo (usually with long exposure time) has to be taken before volatile atmospheric conditions interfere with the photography. So our works are really up to the mercy of the skies.

It is simple to see that the spectral profile immediately around the moon (shape of the "rainbow") depends heavily on the homogeneity of the dispersing elements. i.e. ice crystals and water droplets. To have a "perfect rainbow circle" around the moon, therefore, is to desire an even distribution of a thin layer of almost uniform size of dispersing particulates in our atmosphere.

Layer Cake and Planets

Ok, I got to admit sometimes I see pattern in things that might not actually exist, but hey, if it is for the sake of "finding out" the truth, it might worth the time analyzing the data it provides and say "yup, there's definitely a pattern there.." and so I can use that as an analogy for a concept that is slightly tricky to grasp. 

What now? 

The other day when my brother and his girlfriend traveled to Jakarta, part of the souvenirs he got us was a package of layered cake. Without notice, my mother packed that delicate dessert into my luggage when I move back to my campus after recent general election. 

So when I opened that box, besides the delicious aroma of cinnamon, I saw this:

The cake were craftily layered with its dark lines laden with cinnamon powder (verified upon tasting). Well, from first glance, it seems that the top layers are thicker compared to layers at the bottom. Logic tells us compression from the upper layers during the process of baking forces the still-soft layers at the bottom being pressed into a denser and thus able to "sink" more. 

So, I cut up another thin slice and laid them on a clean white plate while ready my camera for shooting. Assuming the camera was aimed perpendicularly to the plane of the cake, simple measurements can be done to find out the thickness of each layer by the units of pixels (they are digital picture of course). And I have to confess among the excitement to publish a blog post after the idleness from preparing my doctoral thesis proposal, I actually re-sized the photo for publishing before actual measurements were made. Ok, so we lost some resolution, but statistical analysis almost always prove itself useful to solve this kind of problem. 

What I did was quite simple. There are 22 layers in a slice and because the thickness of each layer varies locally i.e. different thickness at different points of the same layer, I measured them from 4 different points. One from the left-most edge, two around the center of the cake and the last from the right-most edge. The arithmetic mean was taken as the average thickness per layer and I plot a graph of thickness of each layer against the layer count where 1 is the top-most layer and 22 is the bottom-most. Here's what I got:

It is (not-so) obvious that the result produced a general trend of shorter layer as it is more bottom compared to the layers on top. Linear regression shows poor coefficient of determination (R squared at 0.22) meaning it is difficult to use this analysis to predict thickness after layer-22 based on this statistics. Nonetheless, some of the error bars (which are contributed by the absolute deviation of points from the mean) are huge denotes the big difference of measured values in the local layer thickness. 

What did we get from the simple analysis? The work was not entirely in vain when we see a general pattern of decreasing thickness over depth of layers: it tells us the layers at the bottom are being compressed by the layers after it and that gave us an insight on how the cake was made. i.e. how patient was the cake-maker in perfecting his/her cake by waiting until each layer has completely solidified from baking before pouring another layer into it. 

So, the idea is about compression: where under the influence of (earthly) gravity, the same substance (of same cake batter) on top is capable of compressing the bottom layer into a thinner and thus more dense state. You can see this more evidently with few soft pillows stacked up to a few layers where the bottom-most pillow will turn out flatter compared to the ones on top. 

This concept has astronomical importance. The structure of planets, how stars get its heartbeat and how because of this eventually lead to its death, are governed by similar mechanism. Without going too far, I'll just take planet Jupiter as an example:

The picture above was taken from NASA's public domain (photo ID: S89-44035) 35mm film taken by mission STS-34 by Galileo entitled "Labeled Drawing of Jupiter Showing its Core and Composition" taken in 9th July 1989. It described: "Labeled drawing of Jupiter identifies fluid molecular hydrogen, transition zone, fluid metallic hydrogen, and possible core and the composition of its atmosphere - cloud tops - aerosols, ammonia crystals, ammonium hydrosulfide clouds, ice crystal clouds, and water droplets."

What I want to emphasize here is the difference between the "hydrogen" evident in layers called "fluid molecular hydrogen" and "fluid metallic hydrogen" in the NASA photograph. Compressed by gravity in a fashion similar to the layers in the cake, hydrogen which constitutes to 90% of Jupiter's mass has been split into two types. Notice the "metallic hydrogen" exist only when it is highly compressed, in a place exceeding 40,000 kilometers beneath the surface of the gas planet! The usual hydrogen "float" on its surface freely as gas while the "special" hydrogen, being compressed, thus with higher density sinks towards the heart of the planet. 

Now this metallic hydrogen is in a special state of the same thing that floats on top of it. It is "strange" because the extremely high pressure caused by the upper layer (about 250 thousand times pressure of our atmosphere) has pressed the usual hydrogen gas into liquid and at this state, this strange hydrogen is able to conduct electricity hence it is dubbed "metallic"!

Currently, there are few literary works that theorizes the existence of such a state and experimentally (on earth), it has been proven difficult to achieve such a state of matter due to the requirement of extreme pressures unlike so conveniently provided by the self-compression of Jupiter's mass. Hydrogen is abundant in our planet and they are mostly locked as a form of water in the oceans (H20) and also there are some parts of it in our upper atmosphere. If anyone manage to make a vial of those amazing fluid, it would definitely hit the newsstand as  "NEW HYDROGEN FOUND AFTER BOYLE IN 1670". 

LUNA: First Attempt On Eyepiece Projection Recording

As per title, this is my first video on the moon: it was recorded using 15 mm eyepiece projection on my Nikon D5000. The sky was not clear as the moon was shrouded by an intermediate layer of alto-cumulus clouds. As such, this causes effect of "silks" flowing through the image of the moon.

Notice the image detail on the edge of this video is distorted. This is due to chromatic and geometric abberation caused by the lens inside the eyepiece. Other than abberation caused by the multiwavelength nature of moonlight, another cause of seemingly random distortion over the image especially on tiny details of the lunar craters which seems like the moon is soaked in a thin layer of running water (with similarity of looking parallel to a surface of a hot sun-baked road in the afternoon) is caused by the atmospheric thermal changes or air flow that causes changes in refractive indices in upper-atmospheric air.

Under such high magnification, we can only see a part of the moon drifting through the field-of-view. After I "found" the moon on its view, my telescope was let stationary. The moon crosses the field-of-view so swiftly thanks to the rotation of Earth itself.

The image sharpness of this video was post-processed with simple Windows Movie Maker (I have yet to find a software with higher capability in video editing) and the video was turned into grayscale to mask the colour dispersion due to chromatic abberation. The name of the classical music is "The Blue Danube" composed by Johann Strauss II in 1866.

Pastiche to 2001: A Space Odyssey? You bet!

Ast. (P) #7 : Planet Venus (phase silhouette)

This image was captured about a week ago with my CMOS webcam. The thing about this webcam is that it has no detector sensitivity or shutter speed control and it tend to change the exposure time automatically according to environment lighting. So with more percentage of the image it detects to be black (it's the night sky I am pointing my telescope to) the computer adjust longer exposure time for my webcam, thus the planet imaged is over-exposed.

Nonetheless, the silhouette of planet Venus can be clearly seen. Venus appear to have a phase, similar to moon having phases in different time of the month from new moon to another new moon. This is a single shot photograph - since this is an overexposed photograph, no stack processing of image is required because no surface features of Venus can be seen due to saturated exposure.

Ast. (P) #6 : First Attempt on Lunar Craters

Seeing condition of the sky wasn't so bad at first when I was strolling to dinner last night, but when I got back to my dorm, clouds starts to accumulate slightly above the horizon. (Will make myself a simple inclinometer soon to estimate the altitude angle) The moon phase was waxing crescent and it is at low altitude due west, so on and off the moon was covered by clouds.

I managed to get a few single shots of the lunar surface near to the terminator using my prime focus webcam. The results are satisfying but not good. No image stacking yet (have yet to explain this method of image processing) so the best quality single shot photo was chosen, then histogram curve and brightness adjustments need to be done using Photoshop in order to get the best viewing contrast.

The disc illumination data is from the internet for this moon phase, I have yet to work out on how to get that numerical value.

Ast. (P) #5 : Planet Saturn

So, earlier this morning I moved my telescope under the window in my dorm where Saturn appears to be bright and in the angle visible through the window. Windows open, telescope cover open and started to find that object.

Because my telescope is essentially Dobsonian mounted and no tracking motors are installed to the mount, so naturally tracking Saturn becomes a difficulty in high magnifications, this is because planets and other celestial objects will move in the sky due to the rotation of earth (The reason why sun rise and set).

# Explanation of the drift motion in high magnification. Skip this part if you are already familiar with this. #

The bigger the magnification ("zoom" of the object) we use to see the object, the faster the object appears to drift away from view if the telescope did not move to compensate earth's rotation. One might think the rotation of earth is slow, but think of it this way: a pilot is flying in a straight line due north from point A to point B and the distance between each other is far, say, 500 kilometers. Now instead of flying to point B as intended, the pilot accidentally changed the course of flight just one degree to the east. After flying 500 kilometers in the new course, he would realize the airplane is now about 8.7 kilometers off course.

Similarly, the magnification represents "how far we can zoom in" hence in bigger magnification, even slight changes in the angle of view will cause huge difference on where we are looking at in the sky (or planets moving away from view if we did not move the telescope according to the motion of the planets).

#Continue on post#

I used a cheap modified webcam (with lens removed) to take the photos directly from the focusser of the telescope, where the image will form on the detector without any lens - this is called prime focus imaging. As opposed to afocal imaging, this method will help in reducing light loss from the multiple lens system and also vignetting in afocal imaging.

After some really time consuming search on the planet Saturn (it's difficult to find the object when the image detector of the webcam is about the size of a few grains of coarse salt) I managed to find that planet. After some focusing to get a sharp image (which the motion of focusing actually moves the telescope so slightly it affects the location of the image on the webcam image detector, with the risk of relocating it!) finally allowed the telescope to stay at the spot where planet Saturn can be seen drifting across the webcam view through time.

So I took quite a few sets of photo each time I readjust the telescope to find Saturn. Out of 28 shots, I manage to find ONE with the best image quality. After little contrast adjustment and turning the picture black and white (the original coloured image has a purplish hue which is not Saturn's "true colour", this could due to the quality of the image detector) I finally manage to post this photo up!

In this photo, a few simple features can be seen. It is noted that the planet has a ring (obviously) and the gap between the ring and the planet sphere body can be clearly resolved. The shadow where the sphere castes on the ring can be seen on the right side of the ring and not sure if this is an image artifact or it could be two barely visible cloud bands of Saturn seen on the top hemisphere.

Ast. #4: About a new (literally) toy

Budget telescope with a homemade mount

It has been some time since I posted anything on this blog.. and lets get to business - no point spending time on lengthy apologizes when we could need the space (pun intended) for "snap n' tell"!

So I have bought myself a really cheap Newtonian telescope online. (at MYR150, that is equivalent to about 50 USD) Now I understand with such budget I didn't expect much from my telescope because I think it is literally a toy. Obviously the eyepieces are made of rather cheap plastics and lets not bother to talk about the corrections in chromatic aberration.

About few months ago when I received the package, the fragile (or rather futile) mount broke on first attempt of operation, so the telescope was left useless until fortunately me and my dad made an Alt-Azimuth mount in his workshop. So after that new mount, the telescope is good to go for eye observations (using the eyepiece of course) but definitely without less difficulty in making a suitable digital image capturing contraption - because seeing with our naked eye is just not enough. With a digital camera capturing the image on the telescope it will ease observations and here are a few reasons why:

1. You don't need to hand-draw the things you see with eye. Hand-drawn observations are prone to error.

2. By knowing the dimensions (size) of the camera image detector, we can do simple measurements on the image which can give us information on the size, rotation period, orbital eccentricity, and other physical property of planets, the moon and the sun.

3. A digital camera installed with controllable shutter (slower shutter speed) or detector sensitivity (high ISO) can capture more light in one exposure compared to the human eye. So, dim objects such as nebula and distant planets can be captured by the camera which human eye cannot see.

4. The photos taken by a camera with high resolution (i.e. high pixel count in a given image detector size) might be able to resolve small image given the image capturing conditions are right.

And many more advantages still to be listed..

So, I spend most of the time during my last month of semester break mostly finding solutions for prime focus photography. At first the focal length was too short to form an image for prime focus imaging, until I made a Barlow lens to extend the focal length into the image detector of my Nikon D5000. I have yet to make a tool to lock my DSLR with the Barlow lens so that stable photography can take place. (now the pictures are taken by hand-holding the camera to the Barlow lens)

In addition to a DSLR, I have a cheaper webcam which I have removed its lens, converting the webcam to a USB prime focus imaging device. The webcam can also take videos so I can video-record the observations I made (there are practical application why recording video is important, will got to that later..)

Anyway, that was the summary about my telescope system. Will update on the snippets of use soon!

Ast. (P) #3: Lunar Eclipse 2011

CLICK IMAGE TO ENLARGE

This is a compilation of photos taken from my digital camera showing in a time lapse of 7 minutes and the phases of the shadowing of moon observed from the living room in my house, convenient much! especially totality (full eclipse of moon) occurred around 3.25am local time. Because the photos are taken without any magnification, the image we see is in fact a small cut-out, enlarged from a relatively high pixel camera. (from my DSLR). This leads to the badly resolved grains seen in the images.

Lunar eclipse occur when the sun, earth and moon are perfectly arranged in a straight line where the earth is in the middle, therefore lunar eclipse can only occur in the night of full moon. The length of lunar eclipse is much longer than solar eclipse is because of the relative size of the moon compared to earth. Think about it it this way:

You're inside your car waiting for the traffic light to turn green. Now you look ahead across the crossroad junction and you saw a an interesting person who catches your eye. (Say, a beautiful lady). Now it is the turn for the east side of the junction to move, and cars are passing in front of you. When a small car passes in front of you, you'll have to wait until the car passes through before you're able to see that lady in front. A car is much smaller than a bus, so, when a bus took its time to cross the road, perhaps that person has already slipped through your eyes, and there's that "oh-well" sigh.

Similarly, lunar eclipse happen because the earth is blocking the sun's light (in the analogy, the beautiful lady being the light source - sun), and solar eclipse is the moon blocking the sun's light. Since the moon is much smaller than the earth, naturally the length of lunar eclipse is much longer compared to solar eclipse.

Another interesting fact explains the mystery why the moon does not completely disappear but instead, appears to be amber or sometimes coppery-red when totality occurs. This is interesting because during solar eclipse, all that we see is a sun being 'eaten' by the moon and nothing in particular happened on the dark shadowed area of the sun.

In a lunar eclipse, the earth blocked the sun's ray. But the earth does not completely block all the light from the sun. A little part of the sunlight passed through the surface of the earth and the light is refracted due to earth's atmosphere which acts like a prism. (refraction of light is the same process that produced the rainbow where the water in the air acts like a prism which split light from sun into the familiar rainbow colours) The refraction of light produced a rainbow likened light which consist of mostly red and blue. This light is then beamed to the moon where during totality (when moon is completely shadowed by earth), the red part of that refracted light hit the surface of the moon, hence the red appearance.

The explanation of the light rays can be better explained graphically HERE.

Ast. (P) #2 : Constellation Taurus

CLICK IMAGE TO ENLARGE

This is the same photo from the last snap n tell, cropped out from a larger image to display the constellation Taurus.

The unclosed grey box is an open star cluster Pleiades., also called the Seven Sisters in the Greek Mythology. Being the closest and brightest star cluster to earth, it's one of the few star clusters you can see with your naked eye.

More information on Pleiades Star Cluster is available here in Wiki.

Ast. (P) #1 : Constellation Orion

CLICK IMAGE TO ENLARGE

This photograph is taken at my new residence in the campus. Even though the sky is dark to the naked eye, the light pollution is immense when viewed through the CMOS sensor of my camera.

Then again, I can finally get a glimpse of how the orion nebula (the square box on the right of the star labelled 'Mintaka') looked like to the naked eye. I'm happy. This photo is a reminder for myself, why I love physics and astronomy. It never fails.