Stargazing Report

 STARGAZING SESSION IN CALIRAYA , LAGUNA

April  9-10, 2005

by Orly Andico

 

Lalai and I once again joined James, 050409-j.jpg (47902 bytes)Allen, Jun Lao, Raymund Sarmiento, Joel Munoz, Jett Aguilar, and some other ALP members at the now-famous   Hilltop Resort in Caliraya, Laguna for what was my first observing session this year. The weather wasn't as good as I would have liked though, on the way to the place I commented that the sky was somewhat overcast (the NPMOC/JTWC US Navy satellite photo for Saturday morning showed clouds over the entire southern Philippines area including southern Luzon).

This was also "first light" for my 10" dobsonian-mounted Newtonian's second iteration, with my shiny new (?) helical focuser constructed from a camera lens. Later that evening I made an annoying and potentially star-party-killing discovery (more on that later).

We were able to set up around 2000 or so; thankfully the sky had (somewhat) cleared although there was a lot of haze. In fact the 3 o'clock star in Crux (delta Crucis) was barely visible to my naked eye. Of course Crux is quite close to the southern horizon, I cannot give an estimate of the zenith limiting magnitude, but it was definitely not as good as the first time I was at Caliraya.

I had a look at the rising Jupiter and M42/M43 through my (in)famous 15x70 Celestron binoculars (I had to do an impromptu collimation session first, because once again they were knocked out of alignment). After setting up the 10" I also had a look at Jupiter and M42/M43 for alignment purposes (to align the cardboard setting circles I'd installed just the previous night).

To my immense annoyance, I discovered that my azimuth setting circle was numbered the wrong way (0 to 360 degrees counterclockwise). Turns out the angular measurements should be in a clockwise direction. Oh well. I was reduced to reading off the Alt and Az coordinates, and subtracting the Az coordinates from 360 degrees, to get the correct reading for my setting circles, all night.

I ended up aligning the setting circles on Polaris (a 1-star align!) which proved good enough, as later observations would show.

A severe problem then showed up when I tried to view Jupiter at higher powers. The tube length I had calculated for the 10" was wrong: I could not reach focus with the 24mm home-made eyepiece when it was barlowed. Actually even the 25mm Meade MA without barlow, would not come to focus. I made a big mistake calibrating the tube length and focuser travel on a building across Ayala Avenue. There's quite a bit of extra in-travel with objects at infinity, versus objects a couple hundred meters away. So I had to spend the entire observing session stuck at 53X, which was not so bad though.

With the help of Astro-Info, my homebrew All Splendours, No Fuzzies observing list for Astro-Info, and the cardboard setting circles I had constructed, I was able to go through quite a lot of interesting objects that night. I didn't have to sweat the alignment because the eyepiece field with the 24mm is almost 2 degrees, so being off a bit was not a deal-breaker; and doing a little panning around would almost always find the desired object.

With the help of my "cheating" setting circles (which Joel commented "defeats the purpose of a dobsonian which is star-hopping") Lalai and I were able to observe more DSO's than we ever did before. And I didn't need to bug Allen or anyone else in order to do so!

We were able to observe M51 without benefit of "cheating," though. The Whirlpool Galaxy showed both bright cores very well, the core of NGC5195 at the 9 o'clock position, and the (larger) core of NGC5194 at 3 o'clock. A faint spiral structure could also be seen with averted vision (I got to practice averted vision a lot during this observing session). I suspect with a better sky M51 would look much more magnificent. It was kind of small though; about 30% of the field through the 24mm eyepiece.

I also had an unexpected bit of fun while finding M51. I started at Zeta UMa, Mizar/Alcor in the Big Dipper's handle (they are very easy to spot). It was a delight to see Mizar's companion clustered close to it, and Alcor in the same field. On to Alkaid, then "overshooting" to Cor Caroli (Alp CVn) in Canes Venatici the Hunting Dogs (which is also a double), then back to Alkaid at the tip of the handle (or, the tail of Ursa Major) and about 1/3rd of the way back to Cor Caroli to find M51.

Using "cheat mode" Lalai and I then viewed M81 and M82 (Bode's Galaxy and the Cigar Galaxy), also in Ursa Major. I never could find this galaxy pairing by star-hopping, so for once I was glad for "cheat mode." M82 was roughly at 8 o'clock in the eyepiece, and M81 at 3 o'clock. Both galaxies were nicely framed by the 24mm eyepiece, and the dark lane in M82 was visible. Although I didn't notice it until Allen asked me if I'd seen it.

Note to self: the 24mm focal length is essentially perfect for this focal length and aperture (10", f5 or 1200mm FL), it gives a sufficiently wide view (about 1.3 degrees) with a nice 5mm exit pupil (a 35mm focal length would result in a 7mm exit pupil, which is pushing it, and I found the eye relief at 35mm to be too long and subject to excessive blackout).

But my home-made eyepiece, even with it's amazing 70-plus degree field, is subject to massive ghosting around bright objects (e.g. Jupiter, Deneb in Cygnus, Vega). I don't know if that was due to atmospheric haze, dew on the eyepiece rear element (I had to wipe off the eyepiece rear element at least three times during the night.. times when stars would get really "hairy" and would not focus down to points anymore), or.. the 7 elements in the home-made eyepiece, most of which are uncoated refugees from Surplus Shed.

Lalai and I then turned our attention to Crux and friends. NGC3372, the Eta Carinae emission nebula/open cluster complex, was magnificent in both 10x50 and 15x70 binoculars, but I could never find it in the 10" scope. Maybe I was passing right over it; the "propeller" shape is quite large, perhaps 3 degrees in span, and too large to see in one eyepiece field.

NGC5139, Omega Centauri, the largest globular cluster in the Milky Way (but not the Local Group -- that distinction goes to the globular cluster G1 in M31) did live up to its hype. From smallish fuzzball in 10x50, to large fuzzball in 15x70, to resolved cluster at 53X (though not to the core). I tried to barlow the 24mm to get around 160X, this did resolve stars to the core (the 24mm plus barlow would reach focus on Jupiter, M4, and Omega Centauri, but nothing else). Oddly enough, Omega Centauri does not look globular to me, but rather like a flattened globe or an egg, with the long axis oriented east/west, at both 53X and 160X.

Antares was also a fine view, with its dim companion, and from Antares it was easy to find M4 (another of my "non cheat-mode" observations). M4 is nice at 53X, showing resolution but not to the core, and is clearly resolved when barlowed at 160X. Actually the view of M4 at 160X is very similar to the view of Omega Centauri at 53X, although not as dense with stars. The member stars showed a pronounced red tint, which is consistent with what we know about M4.

I later also had a look at the open cluster NGC6231, the False Comet (or Baby Scorpion Cluster), in the tail of Scorpius. I skipped over M6 and M7 though, they just didn't seem terribly challenging. James also dropped by and left the scope pointed at the Jewel Box, NGC4755, which was another nice open cluster. I had thought the Jewel Box was a purely binocular object (don't know where I got that idea..), so I hadn't thought to have a look at it.

Back to "cheat mode," I then pointed the scope at the Leo Triplet, M65, M66, and the edge-on spiral NGC3628. All fit nicely into the field, with NGC3628 at 7 o'clock showing a pronounced "flattened oval" shape, M65 at 11 o'clock, and M66 at 2 o'clock. I did not observe any features though (e.g. dark lane in NGC3628). Based on photos of the Leo Triplet on the internet, I would estimate the true field of the 24mm home-made eyepiece to be around 1.3 degrees, giving an AFOV of around 68 degrees.

By this time it was around midnight already, and regrettably Lalai went off to sleep. I revisited the objects I'd seen earlier to pass the time, and using "cheat mode" decided to look for some more DSO's. I was able to successfully observe, in succession, M63 (the Sunflower Galaxy), M64 (the Black-Eye Galaxy, and yes, I was able to see the "black eye"), NGC4631 (the Humpback Whale galaxy in Canes Venatici, larger and "fatter" than M81 or M82). I then turned to M86 in Virgo (which is conveniently listed in the All Splendours, No Fuzzies list) and observed three large galaxies in a row (in a single eyepiece field). I didn't have a high-resolution star map, but I assume those three galaxies are, from northwest to southeast, M84, M86, and NGC4435.

I also had a look at Gamma Virginis, Porrima, a double star in Virgo which Otto Struve calls Pulcherrima, from the Latin word pulchra which means "beautiful" (the last remnants of my high school Latin: pulchra parva stat or "the beautiful girl stood"). I didn't find Porrima very beautiful though; in many ways I thought it was less interesting than bright/dim contrasting doubles like Antares.

At around 0300 of Sunday morning, Lyra had risen appreciably above the trees so I pointed the scope to Vega (showing an annoying halo around this bright star). Without using "cheat mode," I was then able to find M57, the Ring Nebula, which showed a small donut form at 53X. I could not get enough in-focus travel with the barlow, though, so I was denied a higher-power view (it was almost in focus, enough to see the ring shape at higher image scale, but the view wasn't sharp).

I also had a look at Beta Cygni, Albireo, which I think is the most pulchra double star in the heavens. Even at 53X the contrast between the blue and gold companions was very apparent. Again with cheat mode, I viewed Struve 525 in Lyra, which All Splendours lists as "like Albireo." Indeed it is like Albireo, blue and gold although the companions are oriented east-west and not north-south like Albireo. Also, Albireo's components are brighter with more vivid color than the components of Struve 525.

Epsilon Lyrae, the famous Double-Double, is also in this region, but I could not split the components at 160X due to the lack of in-focus travel preventing me from getting good focus.

By this time Scorpius was almost overhead, so I took this opportunity to observe M20 (the Trifid Nebula), M8 (the Lagoon Nebula), as well as the nebulas I had failed to observe last year in April 2004 with PAS. These were M16, the Eagle or Star Queen (Burnham), M17, the Omega or Swan, and M11, the Wild Duck Cluster.

M8 and M20 just barely don't fit in one eyepiece field at 53X. I could barely see the nebulosity which defines the "vee" shape in the Trifid Nebula. M11 in Scutum was nice and tightly-packed, not like the usual open clusters which are scattered all over the place.

I hadn't been able to observe M16 and M17 last year; the view of M16 at 53X was not really special, it looked much like other open clusters, and I don't think the magnification was sufficient to show the emission nebula complex which contains the famous Pillars of Creation.

M17 had me puzzled for quite a while. I knew this was the Omega Nebula, but I had no idea why it was called that. It simply looked like a big curly letter "W" filling about half of the eyepiece field. It was only at breakfast that I realized why -- the curly "W" shape looks exactly like the Greek lowercase letter for Omega. When I think "Omega" I would think of "the end," or perhaps the "O with feet" which is used as the symbol for electrical resistance. It was only at breakfast that I realized "aha! X sub C equals 1 over omega C, and X sub L equals omega L" and connected the curly "W" with Omega.

Lastly (because I had run out of things I wanted to look at), I viewed, via "cheat-mode"/push-to, the globular cluster M54, which is the nucleus of the Sagittarius Dwarf galaxy. Well, it's small as globular clusters go (much smaller than even M4), and unresolved at 53X.

And that's how my observing session came to an end. I went off to sleep, and at 0800 Sunday morning Lalai and I drove back to Manila.

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