July 20, 2009: Henry Coe state park

Julien Lecomte

Jim Harper, Stephen Migol and I met up around sunset at the overflow parking lot at Henry Coe state park. I had a pretty bad experience last time I went to Coe, back in January. However, this time around, the transparency was above average and we got some very decent skies. I did a zenithal NELM test in Lyra, and reached mag 6.2, which is not too bad given the amount of light pollution... The seeing was very soft early on, but slightly improved as the night went on. Temps were in the 60s. There was a fairly strong breeze all night long, which was a bit of a problem for my very lightweight dobsonian telescope. However, by using my car as a shield, I was able to somewhat mitigate the impact of wind gusts.

Henry Coe is the perfect location to get a lot of boring open clusters out of the way, or to do some narrow-banding. I worked in Sagittarius all night, and got some pretty decent views in spite of the light pollution emanating from Gilroy. I took off right around 1am, and was soundly asleep by 2... I'm not used to that anymore! Overall, a fairly decent night. See my log below. Cheers!

Location: Henry Coe state park [Elevation 2600 ft]
Telescope: Meade Lightbridge 12" F/5
Eyepieces used:
- Televue Panoptic 27mm (56x - 1.2° TFOV)
- Televue Nagler 16mm type 5 (95x - 52' TFOV)
- Televue Nagler 9mm type 6 (169x - 29' TFOV)
- Televue Nagler 7mm type 6 (217x - 22' TFOV)
- Televue Nagler 5mm type 6 (305x - 16' TFOV)
(All times are PDT)

NGC 6569 GC Sgr 18h14m17.9s -31°49'29 8.4 mag 09:55p
Moderately small and faint, relatively uniform. The halo takes on a grainy appearance at 219x. Located about 45' E of smaller and fainter globular cluster NGC 6558, giving a nice comparison.

NGC 6624 GC Sgr 18h24m19.5s -30°21'14 7.6 mag 10:00p
Moderately small and fairly bright. Small intense core. Halo resolves in a great number of faint stars during brief moments of better seeing.

NGC 6520 OC Sgr 18h04m02.7s -27°53'20 7.6 mag 10:25p
The central region of this open cluster is made up of about 20 fairly bright stars, seemingly arranged in a circle of about 1.5' in diameter around a pretty bright star with a distinctive orange tinge. A few bright stars are scattered around this area within 8'. Best seen at low power. Amazing crontast with Barnard 86 (a.k.a. the "ink spot") located just to west. I'm wondering whether B86 is located in front of or behing NGC 6520.

NGC 6540 OC Sgr 18h06m59.6s -27°47'38 14.6 mag 10:30p
Barely noticeable as a faint and tiny (1') very unimpressive smudge elongated 2x1 E-W. About half a dozen stars are resolved at 219x. PSA says it's a globular cluster, but it does not look like one and ST mentions it as an open cluster...

NGC 6553 GC Sgr 18h09m55.1s -25°54'26 8.3 mag 10:40p
Moderately large, relatively low surface brightness, surprisingly uniform with no obvious core! Appears very slightly elongated NW-SE? Fairly bright (mag 11.8) superimposed star on the NW side. Generally unresolved, very slight grainy appearance maybe? A few stars pop in and out of view during brief moments of better seeing (not sure whether these are actually part of the globular cluster)

NGC 6544 GC Sgr 18h07m57.8s -24°59'52 7.5 mag 10:45p
Small (about 1'), moderately bright with a tiny fairly bright core. About a dozen brighter stars are resolved at higher magnification. Surrounded by numerous moderately bright field stars. Both NGC 6544 and M8 should fit within the same field of view of the Panoptic 27, forming an interesting couple, although I did not think of observing both of these objects at once.

NGC 6514 (M 20) OC Sgr 18h03m19.2s -22°58'20 5.2 mag 11:10p
Fairly large (about 10'), bright, detected in the finder scope. Absolutely gorgeous at lower magnification with a UHC filter. The dark lanes that split this object in 3 lobes are very well defined. There is a double star in the middle of the nebula. Another nebula, about the same size, is visible, although fainter, slightly to the north.

NGC 6440 GC Sgr 17h49m29.5s -20°21'49 9.3 mag 11:15p
Pretty small (1'), moderately faint, moderately well defined core, unresolved. Forms a really beautiful couple with planetary nebula NGC 6445 located about 22' NNE.

NGC 6445 PN Sgr 17h49m51.5s -20°00'47 13.0 mag 11:25p
Pretty small (about 40"), fairly bright, easily found even at low magnification (95x) Forms a really beautiful couple with globular cluster NGC 6440 located about 22' SSW. At 219x with a UHC filter, appears as a ring very slightly elongated 4:3 NNW-SSE. Brighter arches on the NNW and SSE sides. No central star seen. Moderately faint (mag 12.5) star just 30" WNW.

NGC 6568 OC Sgr 18h13m20.9s -21°36'10 8.6 mag 11:40p
Best seen at low magnification. About 50 moderately bright stars of comparable magnitude, scattered evenly within an area 20' in diameter. At higher magnification, the stars appear to be forming "chain structures" surrounded by darker regions.

NGC 6583 OC Sgr 18h16m26.0s -22°08'02 10.0 mag 11:45p
Compact group made of about 2 dozen stars. Pretty faint, barely noticeable in a crowded star field.

NGC 6629 PN Sgr 18h26m19.8s -23°11'52 10.5 mag 12:00a
Careful star hopping is required to found this planetary nebula as it appears almost stellar, especially in below average seeing. Pretty bright, round.

NGC 6642 GC Sgr 18h32m31.4s -23°28'06 8.9 mag 12:10a
Small, moderately bright, tiny fairly bright core, halo partially resolved at higher magnification.

NGC 6638 GC Sgr 18h31m34.0s -25°29'25 9.2 mag 12:15a
Fairly small, moderately bright, comparatively large core. The halo takes on a grainy appearance during brief moments of better seeing.

NGC 6645 OC Sgr 18h33m12.6s -16°52'34 8.5 mag 12:20a
About 50 stars spread within an area roughly 15' in diameter. Spotted in 9x50 finder scope. Curious oval dark region almost in the middle of the cluster.