This is a guest post—featuring our first screencast!—from Niall Deacon who studies brown dwarfs and white dwarfs in the Pan-STARRS survey at the University of Hawai`i. Niall also blogs about astronomy at weareallinthegutter.
If you are drowning in search windows from different data archives and wasting time writing code to plot graphs of the simplest datasets then maybe it’s time to look at Topcat, a nifty little Java application to make life easier.
There’s a huge amount of astronomical data on the web and Topcat can give you easy access to a big chunk of it. Take for example large surveys like 2MASS and SDSS, these can be queried from the cone search (if you want all the objects in a particular area) or the multiple cone search (for extracting photometry for a list of objects). Want to check your candidates against the literature? Just search for any data table in Vizier and cross reference with it. There is also a spectroscopic database to query against. Want to quickly eyeball a couple of candidates? The activation actions can be used to bring up finders from 2MASS, SuperCOSMOS or SDSS.
Topcat was developed by Mark Taylor at Bristol as part of the UK’s VO program (Astrogrid). While it can be used with other VO tools, I use it as a stand-alone application because it can do everything I want it to do on its own. It’s a Java application which I’ve run on both my Mac desktop and Ubuntu laptop without any issues.
Without an internet connection Topcat is also a useful tool for basic data manipulation and vetting. Take for example a table of candidates you’ve extracted from an archive. Using the scatter plot you can quickly plot up the data, select out a subset that looks interesting and examine it further. It also provides table matching so you could check the dataset against a table of objects you’ve already observed (either by positional matching or by matching a catalogue number). I find this incredibly useful for doing basic data quality and consistency checks.
Rather than just waffle on about how useful it is, here’s a video of me doing a short science project looking for bright members of the Pleiades using Topcat:
One word of warning, like all applications Topcat has memory limits. It displays how much memory it has taken up but it’s a good idea to save your session regularly just in case. As I mentioned before I only use Topcat as a stand-alone tool, anyone who has experiences using it with other VO tools is welcome to use the comments thread to show me what I’m missing out on.
Niall babbles about astronomy with a few other selfish transients (or postdocs as some call them) at weareallinthegutter. He studies brown dwarfs and white dwarfs in the Pan-STARRS survey at the University of Hawai`i and was using his phone voice for the video.