July Challenge Object - NGC3918 (Blue Planetary)

[iceman (Mike)]

Hi all.

We'd love you to take part in the July Observing Challenge. Please post your observing reports and sketches for NGC3918 in this thread. Discussions about the object can also be in this thread.

Please ensure scanned sketches obey the image posting guidelines when you attach them.

For deep-space images of the object, see the "Deep Space" astrophotography forum.

[dhumpie]

Another very easy catch from suburbia and visible in my 15x70's if mounted on a tripod. This one shows a nice disc at 166x and at 300x I see an evenly lit blue disc with no internal structure visible in a 6". I have sketched this one as well but it is just a slightly more swollen "star" in a background of stars. Hard to capture its magnificience on paper. What's striking about it is its color.

Darren

8" f/6 Newt
Pentax 14mm, 10mm & 3.5mm
Seeing 8/10 Trans 8.5/10

02/07/05 @ 19:23 Located using a 14mm XW gives me a starting power of 85x. Sitting relatively alone, on first appearance it wasn't unlike Uranus except with a softer edge. The blue appearance becomes more noticeable the longer you observe, well for me anyways.

Bumping the power up to 120x using a 10mm XW gives a more pleasing view. And benefits with the use of a UHC filter, although no more surface detail could be teased out. One thing I did find noticeable at this power, N3918 appeared to have a faint coma extending some distance out from the disc, around 2-3 disc widths. I didn't seem notice this in either the 14mm or the 3.5mm XW just the 10mm. I'm not sure if this is the halo that is mentioned in the brief. Nor could I resolve a defined outer ring.

Using the 3.5mm gives me 350x and although this frames the planetary nicely, conditions were not optimum for this power. Some surface mottling and there appeared to be 1 possibly two (close together) bright patches that were slightly off center. Not much benif

Difinitely a target to go back to with a larger aperture.

regards