In 1862 Alvin Clark, the famous telescope maker, discovered Sirius B while testing

an 18" Refractor Lens.  Sirius B always appears very close to Sirius and is 10 magnitudes fainter.

This makes it a very difficult object to see visually.  Sirius B has the same mass as our sun but

only one millionth its volume.  That's because Sirius B is a White Dwarf.

The lower a double star is in the sky the more the atmosphere acts like a lens, blurring the image, and making

it more difficult to resolve the pair of stars.  For this reason Sirius B is a challenge of almost mythical

proportions and most people in Northern Countries have not seen it visually.

After reading that the separation between Sirius and its companion is slowly

widening (9.1 arc seconds in 2011) I decided to look for Sirius B.

The crescent Moon and some high thin cloud

were lighting up the sky.  On the ground I had a

Victorian 'full radiation' street light, and several

unshielded neigbhours lights bearing

down on me.

The best defense turned out to be a fur hood!

I flipped this over my head and the eyepiece

while observing.

Orion, Taurus and The Pleiades above the scope.

Sirius is above the EZ Finder to the left.

It was -1 C and ice formed on the scope

and camera gear.

Rigel also has a close companion, with almost the same separation as Sirius from Sirius B.  However

Rigel and its companion are not as widely separated in magnitude and this is a much

easier double to observe.

I found the Rigel pair fairly easily, but it could be missed if you are not aware it has

a companion star.  As I aligned the scope I checked for doubles on a few other stars - noting Polaris'

quite faint companion well separated from it.

Sirius was approaching the Meridian (the East/West border) due South and so was moving towards its

highest and best position for observation.  Even so it would not climb above about 35 degrees in altitude.

I used a 4.3mm W70 Antares eyepiece for 186x on my 800mm FL 8" Newtonian. Sirius sparkled but was a little

muted by the thin cloud that was affecting its appearance on and off. 

I was not seeing Sirius B and had intentionally not looked up its position so as not to cloud my judgement on

detecting it.  About 40 minutes into observing, for just a few seconds, a fleck of light persisted very close

to Sirius.  I moved my eye position around to try to confirm it.  But after about only 5 seconds it was gone. 

There were numerous annoying reflections in the eyepiece which had to be discounted. 

I cannot blame the eyepiece for this as a very bright street light bores almost directly down the scope tube

when I'm looking South.  Despite an OTA that extends well in front of the focuser and a 2 foot long Dew Shield,

the light still spills well into the scope tube.

The Scope had tracked Sirius well past the meridian and the motor housings were close to touching.  I broke off

the pursuit for now.  I attached the camera and took a few test images of The Pleiades to check

for star quality.

I then went back to first Rigel and then Sirius to see if I could pick up the elusive Sirius B on my DSLR.

After that I took another 20 minutes using 372x on Sirius to try to split its companion.  I made a drawing of

the position of another possible candidate that seemed to be flitting in and out of view just above a

diffraction spike, but later after working out its position angle, I ruled it out.

Rigel with its companion hiding in the lower

diffraction spike.  About 20 minutes earlier

it was easier to see visually because of cloud


Sirius and Yes, Sirius B, at the 10 O'clock position

The white halo is a result of thin high cloud which

kept chaing the appearance of Sirius

during observation.

Rigel and its companion, perhaps a little easier to see

with the image inverted.

Sirius and Sirius B (again at 10 O'clock)

I confirmed the star field and Sirius B's

position with an image from


An enjoyable challenge.  Although I did not see Sirius B visually, I am pleased to photograph the elusive 'Pup'

as its called.  Also having knowlege of its appearance I think will make it just a shade easier to

detect visually under more transparent skies.

All Content Copyright © James MacWilliam