M33 (Pinwheel Galaxy)
Size: 73' x 45'
Distance: 3 million light years
RA: 01h 33m 47s
Dec: 30 degrees 39' 21"
M33 is a beautiful, large, and yet
relatively faint spiral galaxy member of our local group.
Although its magnitude is 7.0, it has low surface brightness due to its
large extent (over 1 degree). The most conspicuous characteristic
of M33 is the large number of HII star forming regions it contains,
seen as red regions of Ha emission within the spiral arms. One of
these HII regions, known as NGC 604, is
seen at about 7 o'clock in the above image and extends for over 1,500
light years. More information about M33 may be found here.
Date: November 3, 2004
Sky 90 at f4.5 with field flattener/focal reducer, on the G11 Losmandy
Autoguider: SBIG STV with
Ha filter (13 nm bandpass); Type II R, G, B, plus clear filter set.
18 x 4' for Luminance (clear filter) (72
minutes total, unbinned); 7 x 5' each for Ha (35 minutes total,
unbinned); 5 x 4' each for R, G, and B (20 minutes total
for each color), all unbinned.
Conditions: Temperature 36 degrees F; above average
transparency; average seeing; a bit breezy.
Post-processing: No darks,
flats, or bias frames used. Alignment done in ImagesPlus.
combined using RC Sigma Reject Plug-in for MaximDL. DDP was
performed in ImagesPlus
levels and curves adjustments in Photoshop CS (16 bit format).
The red channel was comprised of an Ha:R mix (100% opacity for R using
lighten mode) in order to highlight the HII regions in the final image.
note: Graphics on this website
may not be reproduced without author permission.
Back to Galaxies