NGC7662

Andromeda

RA 23 25 53.9
DEC 42 32 06

Planetary Nebula

Mag: 8.3

Size: 37"

CS Mag: 13.2

(Please excuse the brevity of this weeks OOTW. I am still recovering from surgery to my left arm and am unable to type properly. Needless to say, one handed typing is a long winded process.)

This week's OOTW is the beautiful planetary NGC 7662 in Andromeda. Discovered by William Herschel in 1784, NGC7662 very much resembles its namesake. Dubbed the "Blue Snowball" by Leland Copeland in the February 1960 issue of Sky and Telescope, Copeland described this objects appearance as "a light blue snowball". The name has since stuck.

One curiosity of this object has to do with its central star. Many sources cite the CS as being in the neighborhood of 12th or 13th magnitude. According to the Strasborgh ESO Catalog of Galactic PN, magnitudes range from 11th to 18th magnitude. 18th! In 1908, EE Barnard using the 40" Yerkes refractor, which happens to be just north of me on Lake Geneva WI, deemed the CS as a variable, varying by as much as 3 magnitudes! So is it? Noones really sure. One possible explanation is that density variations in the shell of the PN is what makes the star appear to vary in brightness.

In the eyepiece, NGC7662 is bright enough to be seen in scopes down to 4". In larger scopes the blue turquoise colors tend to be most apparent and you'll probably need a scope north of 15" to tease out both the inner and outer shells. Elongated SE-NW, the inner shell appears annular in shape surrounding a darker center and both shells appear to be brightest on their NE limbs. Lastly, OIII filters appear to work best with NGC7662.

One final note, has anyone ever seen the extended halo of NGC7662? It extends out quite about from the PN with a diameter of approximately 130". Its visible in many photographs and I assume its within the abilities of many observers here. I do not have any notes annotating observation. Does anyone?

As always,

"Give it a go and let us know!
Good luck and great viewing!"

NGC7662_HST.jpg
Credit:Mike Landherr & the ESA/ESO/NASA Photoshop FITS Liberator