Also known as
Hubble's Variable Nebula, NGC 2261 fans outward from R Monocerotis, a dust-shrouded binary star estimated to be 2,500 light- years distant and only 300,000 years old - a mere infant (though a mighty one) in stellar terms.
Since 1916 it has also been known as
Hubble's Variable Nebula, following Edwin Hubble's discovery that it can change shape on a time scale of months (CCD Astronomy: Winter 1996, page 42).
These include NGC 2261,
Hubble's Variable Nebula, which reflects light from the young star R Monocerotis, and Gyulbudaghian's Nebula, illuminated by PV Cephei (see the images on the facing page).
On the night of January 26, 1949,
Hubble's Variable Nebula had the privilege of posing for the first official photograph taken by the historic 200-inch Hale Telescope on Palomar Mountain.
This wide-field image of northern Monoceros includes the Cone Nebula,
Hubble's Variable Nebula, and the open cluster Trumpler 5 at right.
Of the few in the sky the most well known is
Hubble's Variable Nebula (NGC 2261) in Monoceros.
It was about 1' across when I viewed it, but NGC 6729 is a variable nebula much like the celebrated
Hubble's Variable Nebula (NGC 2261) in Monoceros.
Hubble's Variable Nebula was originally discovered by William Herschel in 1783, but its variability was only noticed by Edwin Hubble in 1916.
All but one,
Hubble's variable nebula, are generally poorly studied.
Known as
Hubble's Variable Nebula, or NGC 2261, it displays a reflecting comet-like nebula with R Monocerotis at the southern tip.
In the eyepiece,
Hubble's Variable Nebula looks like a celestial badminton shuttlecock with a very dense knot on its southern end and a wide, irregular fan extending north.
It resembles the better-known
Hubble's Variable Nebula C46 (NGC 2261) far to the north in Monoceros.