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Planning makes all the difference

Posted By XTSee On October 23, 2010 @ 8:51 pm In Astronomy, C6-SGT, Observing | 1 Comment

This is the first observing session with my Celestron C6-SGT Go-To scope for a very long time. I brought my scope along on our short camping break at Marsh Farm caravan site, Saxmundham in Suffolk, and tonight the damp weather has abated, and the forecast predicted a very cold spell coming in from the North.

Quite right! It was -2ºC last night, with a hard frost on the ground. The site is pretty, with a little river, several carp fishing lakes, islands and bridges, good for astronomy, nice and quiet, with good horizon views all around, and although there are lampposts lit at night, they are not huge floodlights!

I got togged up with several layers to make sure the night would be enjoyable; a T-shirt, then long-sleeve ski vest, plus my favourite chunky knit wool and fleece-lined hooded jacket, then a water/wind proof jacket to keep the heat in. I use ski-Salopettes for my lower half. This is vital, as normal trousers or jeans are useless for keeping legs warm. To finish off, decent water-proof walking boots for feet, and another ski-hat under my hood for my head! I don’t care that I look like a spaceman with all this lot, and at this time of year we are the only caravan on the site anyway.

Sky & Telescope’s September 2010 issue provided the basis for planning my observations tonight. Hugh Bartlett’s article “Binocular Show-pieces for Light-Polluted Skies” was an interesting read, and despite the choice of stellar objects being intended for binocular viewing, due to a full moon tonight the sky will be rather washed out so reducing the likelihood of seeing dim fuzzies.

So I figured it might be interesting to view the suggested objects by telescope. Hugh’s article covered some well-known bright stars, several double-stars, and a few clusters I have not looked at before, and so I felt that it would provide a good plan to stick to, rather than wandering aimlessly around the sky. It turned out this made all the difference for a successful observing session, and learning from this I will endeavour to form and follow a plan in future.

I started setting up around 8pm and took my time levelling the tripod bedding the feet solidly into the grassy ground, then polar aligning my CG5 EQ mount.

There are some things which annoy me about polar-alignment, which make it a laborious process.

One is getting my head down low enough to look up through the polar-scope (despite the tripod set at maximum height). I get a wet knee on the damp grass!

Second, the rear tripod leg is in the way of getting my chin down to get a clear view with my head properly upright to judge the “hour-angle” of the polar-scope, before aligning.

Third, my polar-scope, when fully screwed in, has its Ursa Major/Cassiopeia asterism markings (used for judging Polaris hour-angle) in such a position, that when I rotate the scope about the Right Ascension axis, the motor housing/mount body prevents moving the mount far enough around for the markings to coincide with their respective constellations. This means I currently have to unscrew the polar-scope half a turn to rotate it around so the correct hour-angle can be set, and this is less than ideal because it introduces slop movement, so making alignment more tricky. [Actually I later realized I was being a dunce when I wrote this - if I simply do my polar alignment before mounting the scope, connecting the motor leads, and fitting the counter-balance weight, and rotate the motor housing about the Dec axis to open the view port, but to the opposite side, it will clear the lower parts of the mount when making the hour-angle adjustment].

I use a rough eye-alignment initially to judge the positions of the markings against the constellations, and also I use Jason Dale’s PolarFinder.exe program to indicate more accurately the correct hour-angle for Polaris.

With polar-alignment complete, I then used my illuminated reticule eyepiece to centre the main scope tube exactly on Polaris, so as I could collimate both my finder-scope and red-dot finder (in case they had moved during the journey).

Typically I then forgot to move the scope back to its “park” position (0 RA and 90 Dec), before power-on, and rather frustratingly my first attempt at a 3-star alignment failed. A second attempt proved successful, and resulted in all slews to objects being dead centre every time for the whole of the night. Yay!

Just setting up has taken me one-and-a-half hours! Well, it has been a long time since I last did it.

And of course that time includes;

  • wrapping up warm,
  • carrying all the equipment out,
  • setting everything out conveniently to hand on a table,
  • connecting power supplies, batteries, dew controller,
  • setting out eyepieces,
  • using Tom Tom sat nav to obtain my latitude and longitude (using Windows Calculator on my laptop in Scientific mode to convert the decimal values it shows to degrees, minutes and seconds using the DMS button),
  • configuring the laptop USB/serial connection to the telescope hand controller via StellariumScope/ASCOM, so that Stellarium 0.10.5 can help me locate and slew to the targets I plan to view. I love Stellarium.

So at last I’m ready. Actually I don’t mind this preparation time. It’s all part of the hobby. You need to be patient and precise. If you don’t take your time, and get things done right, you pay for it later, with inaccurate slews to objects, or poor tracking and drift when doing astrophotography.

What can be incredibly annoying is if the weather changes for the worse just after you’ve spent all that time getting ready. Anyway it’s now 9.30pm and I will enjoy a good 4 or 5 hours observing the heavens – not a cloud in sight.

Before I start on my planned list, I look up at the Moon glaring down, with Jupiter big, bright and obvious just below it, beckoning me to take a look. How can I resist? Beautiful, with Ganymede, Io, Europa and Callisto strung out like gems each side, and of course currently only the Northern equatorial belt is visible since the disappearance of the SEB.

Stellarium tells me that Uranus is between Jupiter and the Moon, so I take a quick look and can make out a pin-prick disc of the planet.

Next I run through the targets on my viewing list from the S&T article;

  • M13 mag 5.9, Globular cluster in Hercules, half a million suns 25,000 light years away.
  • M92 mag. 6.4, M13’s near-twin, above the Hercules keystone.
  • v1, v2 (Nu) Coronae Borealis, double-star (mags. 5.4 & 5.6), an orange eye-catcher.
  • v Nu Draconis, double-star (mag: 4.9/4.9), Nu Draconis is a tiny, distant pair of headlights marking the back corner of Draco’s head; unlike most wide pairs this is a true binary of orbiting suns.
  • 16,17 Draconis, double-star (5.4 & 5.5). This pair together with the near-copy Nu Draconis close by, are best seen through binoculars to form a haunting, low-power parallel to the Double-Double in Lyra.
  • Mickey Mouse ears in Ophiucus; I wanted to view p (Rho) Ophiuchi as mentioned in the article, but unfortunately this was too far below the horizon.
  • v1, v2 Boötis; star pair (5.0 & 5.0), a wide gold and blue pair above Boötes head.
  • Mu Cephei; red variable star (slowly/semi-regularly between mags 3.5 and 5.0), this is Herschel’s Garnet Star (HR8316 / HD206936) a strongly coloured pulsating red supergiant some 40% larger than the orbit of Jupiter, found 5º southeast of Alderamin (Alpha Cephei).
  • Taurus Poniatovii; asterism, a Hyades shape v-pattern 4º tall found off the eastern shoulder of Ophiuchus. Poniatowski’s Bull named in 1777 by Polish astronomer Martin Poczobutt after Poland’s king Stanislaus Poniatowski.
  • Alpha Vulpeculae; double-star, (mag 4.6 & 5.9) this wide double can be found to the south of the gorgeous blue/gold pair Albireo in Cygnus, and is a fair contender.
  • The Coathanger; asterism found by following a line from Albireo south through Alpha Vulpeculae, and onward by a slightly greater distance. This chance alignment of stars is also known as Brocchi’s Object or the Cannon Cluster.
  • δ1, δ2 (Delta) Lyrae; double-star, another Albireo substitute, orange-red and blue (mag 4.2 & 5.6) and part of the sparse Stephenson 1 cluster.
  • ε1, ε2 (Epsilon) Lyrae; The famed Double-Double (mag. 5.0 & 5.3). A double pair of stars, each of which is its own close double only resolvable by telescope at high magnification.
  • The Measuring Cup Dipper asterism in Cepheus. Extends 4º NE from Alfirk (Beta) Cephei, which forms its handle end, and 16,17 Cep form its front.
  • a2, a1 (Alpha) Capricorni; Double-star (mags. 3.7 & 4.3). A naked eye pair of yellow-gold stars, a giant and a more distant super-giant. Further below Alpha Cap can be found b1, b2 Capricorni another binocular pair, white & blue-white (mags. 3.2 & 6.1).

Throughout the night I have only needed to turn on my home made dew controller twice for about 5 or 10 minutes each time to clear any condensation from the front glass of the telescope.

Finally at the end of the night Orion has risen further above the horizon, so I take some time to enjoy the great Orion Nebulae M42 and M43 before packing everything up. All in all a successful and enjoyable nights viewing, which made me appreciate much better the difference of star colours, and the benefits of creating a list of things to view, and keeping to the plan.

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