I was at Willow Springs last Saturday night (7/2), a good dark sky site south of the San Francisco bay area, observing with two other Marks (Johnston and McCarthy) - a Three Mark Night, again. Transparency and steadiness high up were excellent - a report from a nearby site had an SQM of 21.75. I observed through my 18" f/4.5 till I was falling off the ladder. I primarily went after planetaries and a few Sh2 targets. As usual, the ones I found most enjoyable were those with something unexpected. Here are two that stood out, and why.
NGC 6842 in Vulpecula was a fine site because star hopping to it, I knew there was a semicircle of stars quite close. When I found it, these stars, the asterism them formed, was really great - providing something visually pleasing while trying to eke out detail in the target. The semi-circle was a nice chain, with a pair of brighter stars wide-spread and bracketing the open end of the half circle, as shown in the attached image. Notes:
20mm - just visible without filter, but with averted vision shape can be teased out, first appeared comma shaped and decent size. Actually round, but with a brighter edge away form a large semicircle of dim stars, open away from the planetary, and bracketed by two much brighter stars.
7mm - no filter, very easy to view, has a sharp edge away from the semicircle of stars which now fit only their closest members in the field of view.
4mm - is this bipolar, with the dimmer side extending farther than first thought, with a size of 1'x1.5'? Back to 7mm but with NPB, shows a much more filled in elongated shape, but still obvious disruption internal, some what darker center. NPB brings out the elongated shape hinted at previously. The nice open cluster N6834 is quite nearby, with a notable bright star in its center, and can be used as a landmark to orient for star hopping to the semicircle and bracketing brighter stars.
Minkowski 1-64 in Lyra was a surprise because of the obvious star just off or perhaps even attached to the planetary, and its unusual appearance and alignment with a pair of bright field stars. Notes:
20mm - visible without filter direct vision.
7mm - appears small and bright, star obvious in one end - at the small angle or vertex of a fan or triangular shaped nebula. At times seems round, so maybe just one bright semicircle with the star at the midpoint, appearing fan shaped when dimmer part of circle fades away from the star.
4mm - gives excellent view unfiltered - planetary is oval shaped with the star off the tip of one end of the major axis, very uneven brightness, brighter toward the star, wider away from the star, brightens narrowing along he major axis toward the star. Guessing 20'x15', A pair of brighter stars 2' apart and aligned along the major axis of the nebula, opposite the dim one at the vertex of the nebula - a night alignment. Is there a bright curved back edge away from the dim star, with a void inside that bright edge?
I found it interesting to read other reports on M1-64, some called it circular and annular, others noted the fan shape. Seems higher power was necessary to see it round, but I was at over 500x and just maybe seeing the back edge.
Fun night! Lots to see, but had to quit when the ladder started feeling "unstable".
Reply With Quote
