Sky & Telescope - July 2023 - 30

Observing Sample
Acquisitions in Aquila
Let's slide over into Aquila, the celestial Eagle, for our next
four targets. Starting at Lambda (λ) Aquilae and slewing 3°
northeast will bring you approximately to NGC 6772. I swept
around there with the 7-inch at 80× using the O III filter but
couldn't see any trace of the 12.7-magnitude, 86″-diameter
nebula. I consulted an online database (I use SIMBAD), and
an image of the area showed three 11th-magnitude stars
forming a straight line about 8′ long north of the planetary's
position. I nudged this line of stars into place at the northern
end of a 17′ eyepiece field at 160×.
Once you've done that, locate the 10.9-magnitude star
that's about 12′ southeast of the westernmost star of the trio.
Draw an imaginary line connecting these two stars, and it
will intersect NGC 6772. Drop another imaginary line from
the 11.2-magnitude central star of the three stars north of
the planetary by about 6.4′, and you'll encounter the first
imaginary line. Most importantly, this brings you to the
northern edge of the planetary (see the image on page 31).
Thus, having pinpointed the invisible nebula with two
imaginary lines (tongue firmly in cheek), I then used every
weapon in my arsenal to try to snag this elusive object. The
bottom-line outcome from a multi-night endeavor was a
qualified " maybe. " I saw something Jupiter-sized a few times
at 160× using a broadband filter with averted vision, but I
could only hold it momentarily. The planetary nebula didn't
respond well to the O III filter or any other time-tested
M 1-59
NGC 6765
method for viewing dim objects, i.e., jiggling the field or
increasing contrast with magnification. So I had to leave it be.
Roy Scheider, who played Police Chief Brody in the movie
Jaws, might have commented in this situation, " We're gonna
need a bigger boat telescope! "
Continuing on northeast from NGC 6772 by 1½° will
bring you to NGC 6778 (also known as NGC 6785). This
12.3-magnitude, 37″-wide nebula achieved a certain notoriNGC
6765
HD 173076
85
δ Sct
47
HD 172981
97
TYC 2640-706-1
111
BD+30 3455
97
HD 172903
85
TYC 2640-544-1
112
35′ × 35′
HANDY CELESTIAL LINES In some cases stars have aligned themselves
in helpful ways to guide you to your target. M 1-59 (in the dashed
circle) lies directly on a line connecting three stars.
10′ × 10′
LARGE BUT DIM NGC 6765's coordinates are in Lyra near the center
of an isosceles triangle of stars that's about 6′ long on two of its sides.
The brightest of the three triangle stars is 9.7-magnitude BD+30 3455,
which points the triangle to the west-northwest. An 11.1-magnitude star
lies 6′ east-northeast of the planetary nebula, and an 11.2-magnitude
star lies 5.3′ to the south-southeast.
30 JULY 2023 * SKY & TELESCOPE
M 1-59: POSS-II / STSCI / CALTECH / PALOMAR OBSERVATORY; NGC 6765 PHOTO:
STEFAN BINNEWIES / JOSEF PÖPSEL / CAPELLA OBSERVATORY; NGC 6765 FINDER
IMAGE: POSS-II / STSCI / CALTECH / PALOMAR OBSERVATORY
Sky & Telescope - July 2023

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