10" dob @ TDS - Part I

Date: 23rd August 08, Saturday
Observation Time: 8:00pm to 12:00pm (4 hrs)
Location: TDS, CA
Weather: Seeing was excellent. Lil bit windy in the end. Slightly hot.
Instruments: My 10” dob & 10x50 binocs
Buddies: Bill and Mohammad from next pad.

Total Objects: 27
New Objects: 9 (Mercury, Neptune and Saggi globular clusters)

This is first time I took this 10" dob to a dark site.. It was a rewarding experience. This aperture is indeed satisfying my thrust :). The saggi globular hunting is a proof of it.

Tried to collimate the dob with Collimation cap, but not precisely. Edward with 17" dob, helped me to collimate it with his howie glatter laser collimator. I really need to buy one.

Started with Venus & Mercury. Venus wasn't sharp.. green ghost shadow with actual image.. indeed out of focus.. also too low on horizon. I guess collimation wasn't perfect. Didn't try any high mags on Venus either. Mercury, a small dot was visible in 9x50 finder, but didn't find it in dob...way low on horizon.. Any way, this is first time i saw Mercury with optics. To make sure collimation is correct, I moved to Jupiter, but still wasn't able to focus clearly... bit frustrating.

< Lyra >
Double Double: At 97x, bare split of double double. It was indeed hard to see anything below that (76x). With 135x and 270x it was fabulous. I guess inter-pair split is probably around 60-70 arc seconds, while each individual pair split might be 1-2 arc seconds. bluish-white star colors. Check Here. Inter-split estimation incorrect.. need to verify again..

At high mag, it was really hard to keep in focus. The spring tension system on the dob is not that great. With both mount springs attached, it becomes too tight, while with single spring, the dob moves lil bit because of its weight. Comparing both options, two springs setup was better and tried to keep the objects in view as far as possible.

Alberio: Fabulous view. nice colors. With 38x, out of focus color contrast was great. with 135x and 270x nice color contrast with sharp focus. 38 arc seconds split. I estimated double double split up values based on Alberio split up.

M57 Ring Nebula: Easy catch: Really nice wide angle view in 38x and ring pops in the view easily. Tried all mags 76x, 135x and 270x... 135x was best view. Outer ring and middle dark hole was clearly visible. Averted vision really helps to view the ring. No colors. No central star visible to me. A field star at 2" clock immediate next to ring (Confirmed)

Binocular Star-hopping:
While confirming location of veil nebula, Mohammad from next pad showed up. It was his first time and he was really exited. So I gave him quick binocular tour of DSOs in Sagittarius M7 Ptlomey's OC -> M6 Butterfly OC-> M8 Lagoon -> M20 Triffid -> M24 Star cloud -> Saggi constellation -> Galactic Center -> M22 GC -> M25 OC -> M28 GC.

Also he asked for M13 GC. I got it in my binocs within few seconds, but it was hard to show him exactly where to look at :). Also tried Omega Centauri GC, but failed. I really need to confirm the location (??)

< Scorpius >
M4 & 6144 GC : Instead of browsing to Veil, I started with M4 Glob. Fabulous GC. No colors. Easy to resolve all outskirts stars. 6144 was also next to it. Out of 6144, M4 and Antares, only two objects can be in the 1.0 deg view at a time. 6144 GC is indeed twice the size of Antares, but Antares is too bright and close, dimming the 6144 brightness.

Northern Jewel Box (6231) : Too low on horizon.

M7 Ptolemy OC: Fabulous yellowish stars in view. At 36x whole eyepiece was full of yellow stars. Heavenly experience

M6 Butterfly OC: Butterfly shape visible in 36x, with Reddish orange star tail. The upper wing is loosely attached on a point to the central body, while lower wing is smaller in size. At 135x (9mm), too much mag to see the shape. also reduced some contrast on orange tail star.

< Sagittarius >
Spent hell lot of time in Sagittarius.

M8 Lagoon + Hourglass : Observed in detail. 36x showed the dark semi circular rift. The right side of the rift (E) has a small open cluster (6530). The bottom part of rift (N), has some nebulosity, while The upper part of the rift (W) has another region of nebulosity. At 76x and 135x, the upper nebulous part shows distinctive features: A bright fuzzy object and two stars aligned in SW-NE line. Fuzziness is larger in size and higher magnitude than those two stars. I think this fuzziness is hourglass nebula and with some creativity, you can imagine the shape @ 270x as hourglass aligned at SW-NE line. (Need to confirm). Deep sky filter would have really helped.

M20 Triffid + M21 : Observed in detail. 36x shows the Open Cluster (M21).. This OC is indeed bigger in size than Lagoon OC. Upper Left (SW) of which, lies the nebulosity. In the Y rift shape the bottom of Y prong is aligned SW-NE and is the only visible rift. Two stars are aligned with it on upper side. while 2 more bright stars defining edge of lower nebulosity. The 72x clearly shows one more star at the center of Y shape. It is also aligned with previous two stars. 76x also reveals the other 2 rifts of Y shape upper prong is more visible than lower prong. 76x reveals that the central star in Y is indeed a double star. 135x view was good too, confirming all details. Deep sky filter would have helped.

Kaus Borealis, M22, M28 & NGC-6638 GC: the 5th star of Tea pot is Kaus Borealis (lambda). I wasn't aware abt the name before. "Kau's" :) !! M22 is fabulous GC.. probably slightly fainter than M4. Looks good in high mags. M28 is also nice, bluish and tiny as compared to M22. Hard to resolve anything in there. while star hopping within 32mm eyepiece (36x), I accidentally saw a tiny GC next to Kaus Borealis, which was smaller in size than M28. Map confirmed that it is NGC 6638. It's probably same size as Antares, but bluish and fuzzy in size. Its like sky-blue color fuzzy dot. Also, map shows a planetary nebula NGC 6644 next 6638 but didn't see anything (confirm the mag and try it next time. ??)