Messier 1 – The Crab Nebula

2021-01-16 M1 Crab Nebula. Stack 160frames 7200s

Supernova Remnant NGC 1952

Magnitude: +8.4
Apparent size:6 x 4 arc min (roughly one fifth of a lunar diameter).
Diameter:10.8 light years.
Distance:6,200 light years.

M1 Timeline:

5146* BCE:
A large star, now known as CM Tauri, erupts in a supernova explosion now called SN1054A.

4179* BCE:
At the age of 967 years, the supernova remnant was emitting photons which would arrive on Earth 6,200 years later, right now in 2021 CE.

1054 CE:
First light on Earth from a new “guest star” (visible in daytime), as the supernova was recorded by Chinese historians.

1731 CE:
The nebula, now known to be a Supernova remnant, was first discovered.

1771 CE:
The nebula becomes the first entry (M1) in the Messier Catalogue.

1844 CE:
The nebula first designated as the Crab Nebula – by someone who must be the only person in the entire cosmos who reckoned it resembled a crab.

1913 CE:
Proximity of Crab Nebula to the 1024 “guest star” established.

1921 CE:
Expansion of Crab Nebula confirmed.

1928 CE:
Confirmation that Crab Nebula and “guest star” are the same object.

1949 CE:
Strong radio emission discovered from nebula.

1963 CE:
X-ray emission discovered from nebula.

1968 CE:
Discovery of Pulsar (a rapidly rotating neutron star) at the heart of the Crab Nebula.

2021 CE:
Telescopes on Earth are capturing photons which were emitted in 4179* BCE.

* approximately, of course.

Image Data

The nebula consists of the remnants of the progenitor star’s atmosphere, and consist largely of ionised helium and hydrogen, along with carbon, oxygen, nitrogen, iron, neon and sulfur.

The outer filaments are visible in the image. Their temperatures are typically between 11,000º and 18,000º K.

After the supernova, the core of the progenitor star became a neutron star and a pulsar, because it was not massive enough to degenerate into a black hole.

This is how Aladin sees the pulsar, using the Panstarrs survey:

Aladin Panstarrs Image of Crab Pulsar
Aladin Panstarrs Image of Pulsar PSR B0531+21 in the Crab Nebula
+ marks the spot.

I would like to think that the faint star in my image, at the centre of the nebula, is the pulsar and progenitor star. It is in the right location and when magnified appears fuzzy and almost merging with the adjacent star but I’m not 100% certain, especially as it is a 17th magnitude star.

So maybe is the best I can say.

I’d always regarded M1 as being potentially a difficult object to image – just something to try “one day”. I don’t know why. However during an earlier session this month I hunted it down with a simple 2 second DSLR exposure which prompted me to at last attempt it with my telescope:

2021-01-11 M1 Crab Nebula Canon 60D 135mm, 2 sec, f/2, ISO3200.
M1 Crab Nebula (faint glow, dead centre)
The bright star (upper right) is Zeta Tauri.
Canon 60D 135mm, 2 sec, f/2, ISO3200.
© Roger Powell
Feature image date:2021-01-16.
Exposure:120 minutes (160 sub-frames @ 45 sec).
Field of View: 76.3 x 50.8 arcmin. Orientation: up is 323° E of N

Location of M1

Telescope Details

SkyWatcher Esprit 120 mm apochromatic 3-element refractor; 840 mm f/l @ f/7.
Field flattener
SkyWatcher EQ6-R Pro mount; ZWO ASI120 guide camera.
Imaging camera: ZWO ASI 071 MC Pro (CMOS 28.4mm 16 Mpx).
Software: EQMOD, PHD2, SharpCap, Gimp.
Observatory location: 34° South.

Images © Roger Powell

I’m a founder member of Macarthur Astronomical Society


  1. As designated “M-1,” this was one of my earliest ‘finds” that I noted in my eventual quest to find Messier objects. A difficult object in less than perfect suburban skies, …but begging for a view in the dark beautiful skies at that time, which were common along the less populated Jersey shore. (not anymore!) Our telescopes at the time ranged from a 2.1″ refractor; a 3″ “Unitron” refractor; a home-made 8″ reflector; a 10″ reflector and a 12″ home made reflector, the latter belonging to a club in a permanent observatory building, unfortunately located in a suburban light – compromised area. Nice images, as always


    1. Some of the telescopes may have been smaller for eyepiece observing in those days but the lower light pollution levels would have compensated – and I’m sure your historical logs will have recorded some very wonderful descriptions.


  2. Impressive image, Roger. You have inspired me to try an exposure with my DSLR.

    I laughed at your comment for 1844 CE. Maybe it refers to the emotional state of the observer.


    1. It’s surprising how some of the early object names have stuck. The Crab doesn’t look like a crab, the Tarantula doesn’t look like a spider. Most of the constellations bear no resemblance to their names….

      At least my recent image of the Horsehead really looks like a horsehead!

      Good luck with your image attempt. Let us know how you go.

      Liked by 1 person

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