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!

On Spectrograph from Compact Disc (Part I)

Image (top) shows a sample of vinyl record and image (bottom) shows the groove of the record disc.

Compact Disc (CD-ROM) or its relative cousins like DVD and Blu-Ray discs works on same physical operating principle similar to the earlier vinyl records where information is etched on a trench shaped groove in spirals on the disc. A needle from the reader machine (like a gramophone player) called the stylus is then placed on one of those grooves. As the vinyl disc rotates, the stylus plough through the groove and the analogue information stored as features on the trench is then converted to electrical signals which is then electrically amplified to produce sound at output speakers which we perceive as audio recordings.

Image (top) shows logo and a sample of Compact Disc and image (bottom) shows microscopic image of the "broken groove" which composed of many tiny "pits" among a flat "land".

In essence, Compact Discs shares similar working principle with the vinyl record except that the grooves in CDs are much smaller. The reader of CDs have stylus but instead of materials, it is a beam of bright light, i.e. laser. A layer of reflective surface is applied to the top-most layer of the CD. The information stored is being "burned" into many tiny holes called pits on the flat plastic below the reflective disc surface called "land". These on and off pits formed a spiral of broken trench like the vinyl record. When laser light is shone on the bottom surface (where the pits and land is located), the difference in height between the pits and land will produce a reflection of light in different intensity which is detected by the reader. These changes of light intensity is then converted to digital signals, which then being processed to produce audio or video outputs.

On Lights From Masking Tapes

About a few weeks back while I was in the dark room preparing small square pieces of x-ray films, I discovered something interesting. The x-ray films are used in plasma-focus diagnostics but that's outside of this story.

What happened was, after preparing those light-sensitive x-ray films, I have to keep them in a light tight pocket. Because x-rays can penetrate the pocket material (usually a black pvc or in my case, a home-made black paper envelope) the films contained inside the pocket will register an image depending on the intensity of the x-ray, just like ordinary films.

Now, making the paper envelope requires a type of adhesive, so I used masking tape. Since I did this in a dark environment, it led me to observe something I could not understand at first.

So this is what happened:

The moment force is applied to the peeled tape, a layer of tape is lifted from the roll. What I saw was a momentary emission of bluish-white light coming out from the contact between peeled tape and the roll. This light only emits when the tape is pulled in a sudden. Astounded by this discovery, I kept repeating it to see if there are changes when I applied force of different magnitude (strength). The colour of the light is the same, but the intensity increases with increasing applied force.

So that night I went online to search what was it and I came across this from nature.com. It appears, if I were to perform this in a vacuum condition I would get x-rays! (what's more is that the x-ray intensity would be high enough to take x-ray images of a human thumb!)

Now since I was working in a plasma technology lab, I asked my supervisor if she's able to provide me a chamber for this test (and they have x-ray detecting diodes too) but she said the set-up is too time costly and took this as a novelty phenomenon.

Well, If I have a lab myself.

It appears that visible light I saw was generated from an effect called triboluminescence, which is an effect where light is emitted when solid material is given a mechanical stress such that chemical bonds are broken/altered to produce light.

Detailed information can be obtained from Wiki.

Big Bang: How The Universe Appeared From Nothing

Here's a cool video on explaining a possibility of the creation of our Universe. I got this link from Main Sequence and thought it would be awesome to share it out!

In the beginning, there was nothing and the idea of nothingness is difficult to put into picture because it is after all, well, completely nothing. Talk about space, not just the distance between stars but also the distance right in front of your eyes, the matter, and energy and light, these all don't exist in the pre-Big Bang history. So, the question was (and still is) Where did all these wonders came from?

Quantum mechanics provides an insight, that at the very early universe when all things are crushed into a tiny point (refer to my previous posts on the big bang), quantum mechanics must have played an important role in the formation process of our cosmos.