Skip to main content

Pulsars and the Ooty Radio Telescope

Well, there's enough content about Quasars on my blog. It's about time i talked about Pulsars - though they sound similar, they are in no way related to one another! Simply put, Pulsars are a Galactic phenomenon i.e they are found in the Milky way galaxy and Quasars are an Extra-Galactic phenomenon i.e they are found in galaxies outside out own galaxy - the Milky way galaxy! 

And, pardon the technical jargon, Pulsars are rapidly spinning neutron stars which emit radiation from their polar regions. And since their spin axis is different from their magnetic axis, the radiation is perceived/observed only when the magnetic axis is aligned to our line of sight! 

Basically, a Pulsar is like a light house. Light is only observed periodically and if you're not standing right in the place - you might not be able to observe it! In the case of the Pulsar, the cone of light is much smaller and the period of the pulses is very small - of the other of milli seconds. 

I was recently part of a Pulsar Observatory for Students program, at the Radio Astronomy Center, Ooty, NCRA-TIFR. During the program, we were taught how the pulsars work, how to observe pulsars and so on. After a couple of days of theory, we were asked to choose a Pulsar from a list of 10, which we would them observe and study! We could either blindly choose a Pulsar or be serious, look at the properties of the 10 pulsars and choose the *best* pulsar, so to speak! So, here's the list of Pulsars we were asked to choose from. 

The Pulsars are named as follows - B0031$-$07 refers to a pulsar observed at an RA of $00hr 31min$ & Dec of -07$^\circ$ and the B refers to the fact that the B1950 epoch positions are used! 

Now, if you're interested or bored, look at the properties of these pulsars and determine which of these you think is the best. To start off, here are some places where you can look for the properties of the Pulsar - ATNF Pulsar Catalogue, NED. And you should rate the Pulsar on it's period, the derivative of the period - which determines the rate at which the Pulsar is slowing down, the dispersion measure - which is a measure of the electron density in the line of sight towards the Pulsar and last but not the least, strength or Intensity of the Pulsar! 
  •  B0031$-$07  --- 00h:31m:36.37s  --- $-$07$^\circ$:38$'$:25.30$"$ 
  •  B0148$-$06  --- 01h:48m:52.61s  --- $-$06$^\circ$:49$'$:51.70$"$ 
  •  B0329$+$54 --- 03h:29m:11.02s  --- $+$54$^\circ$:24$'$:36.93$"$ 
  •  B0628$-$28  --- 06h:28m:51.83s  --- $-$28$^\circ$:32$'$:33.46$"$ 
  •  B0740$-$28  --- 07h:40m:47.81s  --- $-$28$^\circ$:15$'$:33.36$"$ 
  •  B0818$-$13  --- 08h:18m:06.03s  --- $-$13$^\circ$:41$'$:23.04$"$ 
  •  B0833$-$45  --- 08h:33m:39.27s  --- $-$45$^\circ$:00$'$:10.20$"$ 
  •  B0950$+$08 --- 09h:50m:30.54s  --- $+$08$^\circ$:09$'$:45.05$"$ 
  •  B1133$+$16 --- 11h:33m:27.43s  --- $+$16$^\circ$:07$'$:36.77$"$ 
  •  B1237$+$25 --- 12h:37m:11.92s  --- $+$25$^\circ$:10$'$:17.30$"$ 
  •  B1642$-$03  --- 16h:42m:24.69s  --- $-$03$^\circ$:12$'$:30.93$"$ 
  •  B1749$-$28  --- 17h:49m:49.27s  --- $-$28$^\circ$:06$'$:00.70$"$ 
  •  B1857$-$26  --- 18h:57m:42.26s  --- $-$26$^\circ$:04$'$:59.30$"$ 
  •  B1929$+$10 --- 19h:29m:52.04s  --- $+$10$^\circ$:53$'$:04.28$"$ 
  •  B1937$+$21 --- 19h:37m:28.74s  --- $+$21$^\circ$:28$'$:01.35$"$ 
  •  B2016$+$28 --- 20h:16m:0.18s   --- $+$28$^\circ$:30$'$:30.11$"$ 
  •  B2045$-$16  --- 20h:45m: 47.07s --- $-$16$^\circ$:27$'$:52.34$"$ 
For example, I chose the Pulsar B1749$-$28. And if you look at it's properties in ATNF Pulsar Catalogue, the NED database and the Vizier page - you can notice three interesting things.

  • The period of the pulsar is approximately 0.562s. 
  • The strength of the Pulsar is roughly 2000mJy at the ORT (Ooty Radio Telescope) observing frequency of 326.5 MHz
  • The dispersion measure is 50.88 $pc/cm^-3$ - as i mentioned, is a measure of the electron density along the line of sight!
  • The Pulsar lies towards the galactic center and hence the background of the Pulsar is extremely large! 
These are some of the reasons why i chose this Pulsar!
If you're interested and if you have the time, you should look up the properties of these pulsars as well. Tell me which you think is the *best* Pulsar and why! 

PS - I mentioned that the strength of the Pulsar B1749$-$28 that i chose is ~2000 mJy at 326.5 MHz - which is the observing frequency of the ORT. But in the links i provided, only the strengths of the Pulsar at 400, 600 and 1400 MHz are mentioned! I back calculated what the strength of the Pulsar should be at 326.5 MHz using the fact that the Strength of the pulsar is a power law i.e $$S_{\nu} = \nu^{-\alpha}$$ where $\alpha$ is in the range -1.6$\pm$0.3. Refer to arXiv:1302.2053 for more information. Also, you can go through my presentation for more information on Pulsars and my work as part of the POS program.

Popular posts from this blog

Animation using GNUPlot

Animation using GNUPlotI've been trying to create an animation depicting a quasar spectrum moving across the 5 SDSS pass bands with respect to redshift. It is important to visualise what emission lines are moving in and out of bands to be able to understand the color-redshift plots and the changes in it.
I've tried doing this using the animate function in matplotlib, python but i wasn't able to make it work - meaning i worked on it for a couple of days and then i gave up, not having found solutions for my problems on the internet.
And then i came across this site, where the gunn-peterson trough and the lyman alpha forest have been depicted - in a beautiful manner. And this got me interested in using js and d3 to do the animations and make it dynamic - using sliders etc.
In the meanwhile, i thought i'd look up and see if there was a way to create animations in gnuplot and whoopdedoo, what do i find but nirvana!

In the image, you see 5 static curves and one dynam…

on MOOCs.

For those of you who don't know, MOOC stands for Massively Open Online Course.

The internet is an awesome thing. It's making education free for all. Well, mostly free. But it's surprising at the width and depth of courses being offered online. And it looks like they are also having an impact on students, especially those from universities that are not top ranked. Students in all parts of the world can now get a first class education experience, thanks to courses offered by Stanford, MIT, Caltech, etc.

I'm talking about MOOCs because one of my new year resolutions is to take online courses, atleast 2 per semester (6 months). And I've chosen the following two courses on edX - Analyzing Big Data with Microsoft R Server and Data Science Essentials for now. I looked at courses on Coursera but I couldn't find any which was worthy and free. There are a lot more MOOC providers out there but let's start here. And I feel like the two courses are relevant to where I …

Pandas download statistics, PyPI and Google BigQuery - Daily downloads and downloads by latest version

Inspired by this blog post :, I wanted to play around with Google BigQuery myself. And the blog post is pretty awesome because it has sample queries. I mix and matched the examples mentioned on the blog post, intent on answering two questions - 
1. How many people download the Pandas library on a daily basis? Actually, if you think about it, it's more of a question of how many times was the pandas library downloaded in a single day, because the same person could've downloaded multiple times. Or a bot could've.
This was just a fun first query/question.
2. What is the adoption rate of different versions of the Pandas library? You might have come across similar graphs which show the adoption rate of various versions of Windows.
Answering this question is actually important because the developers should have an idea of what the most popular versions are, see whether or not users are adopting new features/changes they provide…