Ever since I first bought Uranometria 2000.0 in the mid nineties I have been intrigued by the sheer amount of planetary nebulae in the Scorpius and Sagittarius area. But apart from several bright ones (with NGC and IC designations) I never really tried to track them down. Partly because I used to live in the Netherlands and that part of the sky doesn't rise high above the horizon, partly because there are so many other objects to observe.
Last night I went to my reasonably dark observing site some 20 km from my home west of Madrid in Spain and I gave a few of them a try. During the afternoon clouds started to build up but in the evening they more or less dissolved again. When I arrived at my observing site there still were some to the north but south was clear. During the observing session, which only took 45 minutes, clouds built up again and in the end I had to go home. But I did manage to track down four of them. My SQM indicated 20.3 which isn't bad for that site but I have seen 20.5 and even 20.6. Anyway, here are my observations which were all done with my 12" F/5 dob, an 8 mm Ethos eye piece and Lumicon UHC and OIII filters.
PK 355-4.1 was visible without filter at 188x in a small group of two or three stars north of an oblique rectangle of faint stars. Not sure which of these two or three stars is the planetary nebula. A UHC filter transforms one of the stars into a faint smudge. An OIII filter increases the visibility of the smudge.
PK 355-3.3 was visible at 188x in a group of five stars. Of these five, three were in a line west east and two in another, parallel line slightly north. To the west south west I saw a brighter star and another a little further away and a triangle of stars still further away. On the other side of the group of five I saw a double star and a little further away a brighter star. Close inspection shows that the eastern most star of the line of three is a double star too. With an OIII filter the middle one of the three becomes much better visible. No sign of nebulosity.
PK 356-4.1 is visible at 188x as a faint star north of an m=6.1 star at the northern edge of M 7. Between the bright star and the nebula, and slightly to the west, I see a line of three stars that get fainter going north. Using a UHC, and even more with OIII, the two fainter of those three stars disappear and the nebula becomes visible better. Without a filter I thought I noticed some nebulosity but I think that was due to some faint stars close to the nebula because it disappears when I apply a filter.
PK 356-4.2 is visible close to a pentagon of reasonably bright stars. The most eastern tip of the pentagon is formed by a double star formed by a reasonably bright star and a faint companion to the north west. South east of this double star I see a faint double star. Without filter I see no nebula. Using UHC suddenly a small sphere appears between the two double stars. An OIII increases the visibility of the sphere. However, UHC gives a more pleasing view since the surrounding stars remain visible.
There was a very good article on the planetaries near M7 by Jack Marling in the Summer 1988 edition of deep sky magazine (number 23) That might be of interest to you. Yes I know I have been in the game too long to remember that far back :-)
Many thanks for pointing me to the deep sky magazine issue #23, Owen. Quite a challenge to try and observe all these planetaries in the vicinity of M 7. Challenge accepted
You can download all the issues of Deep Sky magazine, just google Deep Sky Magazine download. I have them all and refer back to them from time to time.
They are also fun to read to see the ads and such. The hobby has come so far!
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