Martin Krzywinski / Genome Sciences Center / mkweb.bcgsc.ca Martin Krzywinski / Genome Sciences Center / mkweb.bcgsc.ca - contact me Martin Krzywinski / Genome Sciences Center / mkweb.bcgsc.ca on Twitter Martin Krzywinski / Genome Sciences Center / mkweb.bcgsc.ca - Lumondo Photography Martin Krzywinski / Genome Sciences Center / mkweb.bcgsc.ca - Pi Art Martin Krzywinski / Genome Sciences Center / mkweb.bcgsc.ca - Hilbertonians - Creatures on the Hilbert Curve
I'm not real and I deny I won't heal unless I cry.Cocteau Twinslet it gomore quotes

b: 2


DNA on 10th — street art, wayfinding and font


data visualization + art

If you like space, you'll love my the 12,000 billion light-year map of clusters, superclusters and voids. Find the biggest nothings in Boötes and Eridanus.

IAU Sky Constellation Resources

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create (a place)
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— Viorica Hrincu

Having recently drawn a few skycharts (Superclusters & Voids, Sanctuary Project), I was frustrated by the lack of parsable resources for the IAU Constellations.

Finding a plain-text parsable definition of the asterisms proved impossible. So I created my own.

IAU Constellation Shapes

DOWNLOAD CONSTELLATION SHAPE FILE

DOWNLOAD YALE CATALOGUE OF BRIGHT STARS POSITION FILE

# CHANGE LOG
# 
# 29 Nov 2018
#  + line between Betelgeuse (HR 2061) and Bellatrix (HR 1790) in Orion added
#
# 27 June 2018
#  + Greek designations now a separate field
#  + fixed Proxima Centauri and Barnard's Star, neither of which
#      are in BSC

All the constellation shapes were derived by manually examining the IAU map and cross-referencing the stars to the Yale Catalogue of Bright Stars.

The list of IAU constellation shapes in the file linked to above conveniently includes the J2000 right ascention and declination for each stars in the pair, along with their HR index, magnitude, Greek letter designation and name. See the file header for all the details.

For example, Cassiopeia's familiar "W" appears as 4 lines that indicate the connections between HR stars 21-168-264-403-542.

Cas  21  2.294583 59.149722 2.27 bet Caph|bet Cas|11 Cas	        
    168 10.127083 56.537222 2.23 alf Schedar|alf Cas|18 Cas
Cas 168 10.127083 56.537222 2.23 alf Schedar|alf Cas|18 Cas	
    264 14.177083 60.716667 2.47 gam BU 499A|BU 1028|gam Cas|27 Cas
Cas 264 14.177083 60.716667 2.47 gam BU 499A|BU 1028|gam Cas|27 Cas
    403 21.454167 60.235278 2.68 del Ruchbah|BUP 19A|del Cas|37 Cas
Cas 403 21.454167 60.235278 2.68 del Ruchbah|BUP 19A|del Cas|37 Cas
    542 28.598750 63.670000 3.38 eps Segin|eps Cas|45 Cas

The names are obtained from IAU Catalog of Star Names (IAU-CSN) and Simbad's name fields "NAME", "*" and "**", in that order. You can conveniently browse the Simbad database by any star identifier. For example, for Sirius the URL is http://simbad.u-strasbg.fr/simbad/sim-id?Ident=sirius.

Please report any errors to me.

Bitmap, SVG and PDF Constellation Shapes

The shapes of all the constellations and the stars that define the asterisms shown in the image below. I also include all the 110 Messier objects with common names in this map (hollow circles).

The map also shows the galactic equator and the ecliptic. The vernal equinox, summer solstice, autumn equinox and winter solstice occur along the ecliptic at right ascension 0/360 (Pices), 270 (Sagittarius), 180 (Vigo) and 90 (Gemini/Taurus).

Whole-sky star charts are traditionally drawn with 360 right ascention on the left in decreasing order towards 0 on the right.

Shapes of IAU Sky Constellations / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
All 88 IAU constellations and their stars. Also included are all 110 Messier objects.

You can download this file as PNG, SVG or PDF.

If you're interested in more astronomical resources, check out my Universe Superclusters and Voids resource page.

Detailed Sky Chart

I've also created detailed charts that include all the 9,110 stars in the Yale Catalogue of Bright Stars. These are labeled by their Greek designation with the constellation as well as with their IAU name.

Shapes of IAU Sky Constellations / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
A closeup of the detailed map in the region of Auriga and Perseus. The Pleiades can be seen at the bottom right.

The maps also show all 110 Messier objects, labeled by their index and, where available, a common name. All the labels in these maps have been lovingly adjusted manually to avoid ambiguity and overlap. Available are blue, black and white background versions.


 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca buy artwork
Sky chart with all 9,110 BSC stars, 88 IAU constellations and all 110 Messier objects. Where available, objects are labled with their common name. Also shown are the galactic equator and the ecliptic. (BUY ARTWORK)

 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca buy artwork
Sky chart with all 9,110 BSC stars, 88 IAU constellations and all 110 Messier objects. Where available, objects are labled with their common name. Also shown are the galactic equator and the ecliptic. (BUY ARTWORK)

 / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca buy artwork
Sky chart with all 9,110 BSC stars, 88 IAU constellations and all 110 Messier objects. Where available, objects are labled with their common name. Also shown are the galactic equator and the ecliptic. (BUY ARTWORK)
VIEW ALL

news + thoughts

Hola Mundo Cover

Sat 21-09-2019

My cover design for Hola Mundo by Hannah Fry. Published by Blackie Books.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Hola Mundo by Hannah Fry. Cover design is based on my 2013 `\pi` day art. (read)

Curious how the design was created? Read the full details.

Markov Chains

Tue 30-07-2019

You can look back there to explain things,
but the explanation disappears.
You'll never find it there.
Things are not explained by the past.
They're explained by what happens now.
—Alan Watts

A Markov chain is a probabilistic model that is used to model how a system changes over time as a series of transitions between states. Each transition is assigned a probability that defines the chance of the system changing from one state to another.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Nature Methods Points of Significance column: Markov Chains. (read)

Together with the states, these transitions probabilities define a stochastic model with the Markov property: transition probabilities only depend on the current state—the future is independent of the past if the present is known.

Once the transition probabilities are defined in matrix form, it is easy to predict the distribution of future states of the system. We cover concepts of aperiodicity, irreducibility, limiting and stationary distributions and absorption.

This column is the first part of a series and pairs particularly well with Alan Watts and Blond:ish.

Grewal, J., Krzywinski, M. & Altman, N. (2019) Points of significance: Markov Chains. Nature Methods 16:663–664.

1-bit zoomable gigapixel maps of Moon, Solar System and Sky

Mon 22-07-2019

Places to go and nobody to see.

Exquisitely detailed maps of places on the Moon, comets and asteroids in the Solar System and stars, deep-sky objects and exoplanets in the northern and southern sky. All maps are zoomable.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
3.6 gigapixel map of the near side of the Moon, annotated with 6,733. (details)
Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
100 megapixel and 10 gigapixel map of the Solar System on 20 July 2019, annotated with 758k asteroids, 1.3k comets and all planets and satellites. (details)
Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
100 megapixle and 10 gigapixel map of the Northern Celestial Hemisphere, annotated with 44 million stars, 74,000 deep-sky objects and 3,000 exoplanets. (details)
Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
100 megapixle and 10 gigapixel map of the Southern Celestial Hemisphere, annotated with 69 million stars, 88,000 deep-sky objects and 1000 exoplanets. (details)

Quantile regression

Sat 01-06-2019
Quantile regression robustly estimates the typical and extreme values of a response.

Quantile regression explores the effect of one or more predictors on quantiles of the response. It can answer questions such as "What is the weight of 90% of individuals of a given height?"

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Nature Methods Points of Significance column: Quantile regression. (read)

Unlike in traditional mean regression methods, no assumptions about the distribution of the response are required, which makes it practical, robust and amenable to skewed distributions.

Quantile regression is also very useful when extremes are interesting or when the response variance varies with the predictors.

Das, K., Krzywinski, M. & Altman, N. (2019) Points of significance: Quantile regression. Nature Methods 16:451–452.

Background reading

Altman, N. & Krzywinski, M. (2015) Points of significance: Simple linear regression. Nature Methods 12:999–1000.

Analyzing outliers: Robust methods to the rescue

Sat 30-03-2019
Robust regression generates more reliable estimates by detecting and downweighting outliers.

Outliers can degrade the fit of linear regression models when the estimation is performed using the ordinary least squares. The impact of outliers can be mitigated with methods that provide robust inference and greater reliability in the presence of anomalous values.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Nature Methods Points of Significance column: Analyzing outliers: Robust methods to the rescue. (read)

We discuss MM-estimation and show how it can be used to keep your fitting sane and reliable.

Greco, L., Luta, G., Krzywinski, M. & Altman, N. (2019) Points of significance: Analyzing outliers: Robust methods to the rescue. Nature Methods 16:275–276.

Background reading

Altman, N. & Krzywinski, M. (2016) Points of significance: Analyzing outliers: Influential or nuisance. Nature Methods 13:281–282.

Two-level factorial experiments

Fri 22-03-2019
To find which experimental factors have an effect, simultaneously examine the difference between the high and low levels of each.

Two-level factorial experiments, in which all combinations of multiple factor levels are used, efficiently estimate factor effects and detect interactions—desirable statistical qualities that can provide deep insight into a system.

They offer two benefits over the widely used one-factor-at-a-time (OFAT) experiments: efficiency and ability to detect interactions.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Nature Methods Points of Significance column: Two-level factorial experiments. (read)

Since the number of factor combinations can quickly increase, one approach is to model only some of the factorial effects using empirically-validated assumptions of effect sparsity and effect hierarchy. Effect sparsity tells us that in factorial experiments most of the factorial terms are likely to be unimportant. Effect hierarchy tells us that low-order terms (e.g. main effects) tend to be larger than higher-order terms (e.g. two-factor or three-factor interactions).

Smucker, B., Krzywinski, M. & Altman, N. (2019) Points of significance: Two-level factorial experiments Nature Methods 16:211–212.

Background reading

Krzywinski, M. & Altman, N. (2014) Points of significance: Designing comparative experiments.. Nature Methods 11:597–598.