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Showing posts from October, 2012

I wish i were a machine

Well firstly, let me tell that you i've been trying to write atleast twice a week for the last 4 months. It was one of the few things in my life that i was trying to do on schedule. Granted, i wasn't always able to get 8 posts a month but i've been able to squeeze 6/7 out on an average.
Now, coming to the point, i haven't been able to do the same for the last 2 weeks. For one, i was sick for most of the last 2 weeks. And on top of that, i've been going through a strange patch in my life and my mind is being constantly bombarded by thoughts, ideas and what not. I've thought, more than once in the last two weeks, of making a pill/machine that will help a person completely shut down their mind; no thoughts while you lay on your bed; no dreams; nothing. I haven't been productive at all; missing classes, falling behind on assignments, i kept wondering how it would be if i were a machine.

Seriously, what if i were a machine instead of a human. 

To start with, i w…

Interesting arXiv papers for the week

I thought i'd start something new this week.
I shall start reading and understanding atleast 5 papers from this week on.

While i was doing this in the 2010 summer as well, i couldn't understand most of the papers. I was just looking for interesting facts or snippets of awesomeness in the papers. Now that i've reached a position in my academic career where i can't keep brushing over the details, i thought this would be a good way to keep working on problems and understand new topics.

So, the papers for this week are -

Multi-Band Feeds: A Design Study - is a paper on the antenna architectures. There are certain types of antennae known a Log-Periodic Antenna or Eleven Feed antenna which have a broad observing bandwidth. Though a broad observing bandwidth is a good thing, RF Interference will dwarf the astronomical signal in certain parts of the band!

Inorder to avoid this, a new antenna architecture has been designed, simulated and implemented which has the capability to …

Energy from the Stars : The ElectroMagnetic Spectrum

This is second in a series of articles on the basics of astronomy and observational techniques. you can read the first article here. The articles will broadly cover the different kinds of telescopes used for the different energetic phenomenon associated with astronomy. In the previous article, the reader was hinted at the possibility of observations being carried out outside the visible spectrum using specific instruments. In this article, i will describe the different energy levels observed in astronomy and their associated phenomenon. I will mention the new telescopes which are observing emissions in these exotic bands and leave you to read further. 

ElectroMagnetic Spectrum - as we all know, the electromagnetic spectrum can be roughly divided up into - 
Gamma Rays X Rays UV rays Visible Light IR rays Microwave radiation Radio wavesthis should help you better recollect the frequencies and wavelengths of the corresponding waves and also get an idea of the respected energies involved wi…

Finally, we're getting somewhere.

So, i finally met the professor whom i've been stalking for almost 3 weeks now! I kept mailing the prof and swinging by his room, hoping that he'd be there. And last wednesday, i finally met him, Prof. HSR, a professor in the Elec Dept at IIT Madras. He's known to be a pundit on antenna design and simulations. When i started working on the radio astronomy project, as senior had asked me to contact him regarding any doubts and more fundamentally, the direction in which my project would head. 

well, now that i've finally met him, i did get quite a few doubts cleared and know what i'm supposed to be doing in the coming months! 

Apparently, as i suspected, the response function of the antenna or the gain from the antenna is frequency dependent and trying to deconvolute the signal (in the frequency spectrum) from the antenna without the proper response function is moot! 

Also, in addition to the response function, the effective aperture of the antenna is also frequency dep…

Experiments with Z moon

A couple of days back, we were really bored and we just got up and moved to the rooftop of the physics dept to try do some astro-photography.

and here's what came of it -

they are all pics of the same moon on the same night.
the difference is the camera settings - The ISO and shutter speed.
from what we realized, we suggest that you guys use

ISO 100 at 1/30,1/60;
ISO 200 at 1/60, 1/100;
ISO 400 at 1/250, 1/600 and even 1/1000.

The DSLR we used was a Canon 550D.

ps - you need a telescope along with the usual camera to be able to take such pictures.

Radio Astronomy - The Observable Range

A really important hurdle to clear in the process of radio astronomy is to decide on a frequency band to listen to and this is not a trivial process. because there is quite a bit of terrestrial communication(comm) signal and extra-terrestrial satellite comm. signals, we can't just build a antenna at any frequency and expect to be able to see extra-galactic radio signals. 

This was one of the things i was having a hard time figuring out because there apparently are quite a few bands where we have less comm. noise but no explicit information on the spectrum allocation and the bands alloted specifically for radio astronomy. 

I browsed through pages finding partial answers like this one, which is relevant to australia and gives a brief outline of the bands where one can try observe using a radio telescope without having to worry about comm noise. 

but that still wasnt satisfactory because i wanted to look at the indian scenario. 
and then i struck gold. The National Frequency Allocation P…