May 21/22/23 - A bit of everything - Skymax 127

[Jove]

Date: 21/5/2010, 22/5/2010 and 23/5/2010

Place: NW London

Time: From 2230

Seeing: variable

Equipment:

Nikon 10x50 bins

Skywatcher Skymax-127 scope (f/11.8)

Various Plossl eyepieces: 9mm (167x), 12mm (125x), 15mm (100x), 20mm (75x), 40mm (37.5x), 2x Barlow

It seems a long while since I was last able to spend much time out with my scope. Other commitments and a lack of clear skies have kept me away, so the last weekend, with three warm clear nights was very welcome.

Things in the sky have moved on since last I took anything more than a cursory glance at the night sky. Mars and Saturn are disappearing into the east as the Earth leaves them behind. Arcturus dominates the southern vista with Vega a rising force in the west.

The Moon was advancing from first quarter towards full Moon over the weekend. Observing several nights in a row gave me a new appreciation for it - in particular the way in which new landscapes are revealed as the sun slowly rises, as seen from the Moon. Using a relatively high power (200x or so) many individual craters and features are visible. On Saturday, Clavius, emerging from shadow, was particularly striking. Creeping along the terminator I was struck by an observation I had failed, in my impatience, to make before: The peaks and ridges of mountains in shadow are picked out by the sun and appear as flecks and dashes of illuminated terrain shining, surrounded by darkness, hinting at the unseen mysterious landscape as yet unlit. This put me in mind of the highest buildings in London, the tops of shine gold in the sun long after night has fallen on the rest of the city. Sunday offered a yet more impressive sight: The towering cliffs of Sinus Iridium were perfectly picked out by the sun. The scale of these rising above the lunar plain is staggering. The Moon, I find is slightly eerie to observe. Unlike the planets, and certainly objects deeper in space it feels somehow less abstract - and though familiar, at close inspection is revealed to be quite alien, there is almost something Lovecraftian about it. I think this is its charm for me - while there is perhaps less to interest the physicist in me, it makes up for it in poetry.

Scarcely, if at all, less poetic than the Moon is Saturn, which while a waning force in the sky is still a magnificent sight. Once again, several consecutive nights of viewing revealed a side to it I had not appreciated enough before: the motion of its moons.

My sketches are not especially accurate - measuring distances in the eyepiece is not easy without any kind of reticule - and monospaced fonts are not a high precision medium, but I approximate the positions of the visible moons on the nights from the 21st were roughly as follows:

21_____T_r___O_______

22_T________rO_t_____

23_______T___O__r____

24__________TO____r__

<-East West->

O=Saturn, T=Titan, r=Rhea, t=Tethys

Saturday offered particularly good conditions and I was able to also pick out Dione, close to Rhea - a pleasing first. I also made an unconfirmed sighting of Iapetus, roughly 'above' Titan on the 22nd. Iapetus's brightness varies from 10.2 to 11.9, so if it was Iapetus that I saw then it must be at the brighter end of its range. I was unable to track it over several nights, as the Moon grew brighter it became harder to pick out the fainter satellites.

I spent a little time tracking down some double stars, which are always interesting to see. Over the course of the weekend I looked at some familiar doubles: Xi and Pi Bootes, both split at 167x both are attractive, Xi in particular.

STF 1835 is a double in southern Bootes - it resolved at 125x into a white and orange pair. Porrima (gamma Virginis) was a tricky split - it required using a barlow to split at 334x - the pair appeared blue and gold. Each sat within the Airy disc of the other.

Moving East, I tracked down the two variables R and T Corona Borealis. Or rather looked where they should appear. Both spend much of their time below the limiting magnitude of my telescope, though for opposite reasons. From time to time R CrB, a 'carbon star' belches clouds of carbon soot that dim it from its 'normal' magnitude of around 6. It was scarcely visible to me so I conclude it is currently obscured, and is of magnitude no brighter than 10.5. T CrB is an eruptive variable, and is dubbed the 'blaze star' for its (to my knowledge) unpredictable increases in brightness from around 10.5 to 3 or higher. On the nights I observed the star it was slumbering peacefully around mag 10.5, hopefully I will see it flare in my lifetime, patience is such an important attribute for the astronomer!

By midnight Hercules and Lyra had risen to a respectable altitude for observation. Ras Algethi (Alpha Herculis) is perhaps the most peculiar double I have seen so far - splitting at 167x into an orange and green pair! The eye perceives a green star due to its contrast with its bright orange companion. Lyra is home to the spectacular double-double, Epsilon Lyrae. All four start were visible at 167x, quite a sight. At low powers the area around Lyra, down towards Aquila is quite magnificent. The milky way runs down the sky here and provides views of many rich star fields.

I managed to see a couple of Messiers over the weekend too. I was expecting great things of M13 - and while bright I was disappointed that I could not resolve it into stars - perhaps a darker sky would help. What disappointment I may have had with M13, however, was more than made up for by views of M57, the Ring Nebula. It was clearly visible at even 37.5x, and took magnification suprisingly well - 150x was achievable. I found the best view to be had around 75x using a nebula filter (Orion Skyglow). I could see the annular structure of the nebula quite clearly, with the rim brighter than the centre. There was a greenish tint visible, though this may have been due to the filter.

All in all a wonderful weekend of observing. The warmth made the whole experience rather more pleasant than the sub-zero temperatures a few short months ago!

Thanks for reading!

[DarkerSky]

Super report. Alpha Herculis sounds like an intriguing double. On my list for next time out

[lunator]

Very nice report

Cheers

Ian

[DarkerSky]

I checked out Alpha Herculis last night. A superb double to view IMO. Got hints of green and yellowness to the secondary component. All very intriguing