The importance of good skies

As mentioned at the last couple of meetings, I’ve been taking every opportunity to catch a photo of comet C/2012K1 (PANSTARRS) making its way across the night sky.  It has brightened to about Magnitude 8 at the moment, but as the nights get shorter around the summer solstice, it becomes harder to photograph a such diffuse object against a dark sky.

Here is my effort from last night (to be precise, early this morning), highlighting several issues that upset good astrophotography.  20 exposures of one minute each, stacked together with the 20 frames aligned on the comet – so the stars appear as short lines because the comet has moved a slight amount from one exposure to the next.

2012K1_20140609_0028_White

What are the issues ?

1.  At this time of year, the Sun dips only 12º below the horizon at night.  Full astronomical darkness needs 18º below (which won’t happen again until the 3rd of August), so in astronomical terms the sky isn’t really dark.

2.  The comet is visually only about 60º away from the Moon, which is also above the horizon and more than half illuminated.  The moonlight lightens the background even more than the twilight, making it hard to distinguish the comet tail.

3.  Although the sky looks clear to the eye – and there are no clouds visible – there is a high level of humidity (about 90%).  The humidity catches the moonlight and creates the illusion of streaks across the sky as the telescope mount tracks the movement of the stars.

4.  The comet is now only 25º above the horizon, which means it is being photographed through much more of the Earth’s atmosphere.

Compare the result with an earlier photo, which was processed identically to the above.  This one was taken on the 26th of April in full darkness, with no Moon, 60% humidity and the comet at an elevation of 83º (almost vertically above the observer).

2012K1_20140426_2303_White

Even though the comet is a couple of magnitudes fainter, it is much more distinct in the photo.  Dark, clear skies are the key.

Simon

 

12th May 2014 – Meeting

The meeting was well attended (around 40 members) and Stuart Atkinson kicked off with a description of his recent observing sessions, and the resulting beautiful photos. EAS members have been searching all round Kendal and the surrounding areas for good observing sites, and we have tracked down quite a few dark places. As well as finding places suitable for an evening session, some members are interested in sites where we could hold our own Starcamp. Stuart has found a local campsite that would offer very dark skies but is quite close and accessible.

That would be for later on in the year. In the meantime, there has been a prediction of a possible meteor shower on 23/24th May 2014, from a new trail of dust, i.e. not one of the regular showers. Since it is new, no-one knows how bright it might be, but we are always hopeful, and a Meteor Watch is planned up on Scout Scar for the night of the 23rd. This will not be a public event, just for EAS members.

Stuart also reminded everyone to look out for noctilucent clouds, as we are approaching the season for them There were some really good ones last year, and several members got good photos.

After the break, we had a presentation from Simon White, who explained the hard work that goes into his amazing photos (and also the occasional glitch!). He had managed to capture comet PANSTARRS c/2012 K1 and M51 in the same frame, but they put up a fight.

Simon was followed by Ian Bradley showing his holiday snaps of the restored 72″ telescope built at Birr in Ireland by the 3rd Earl of Rosse in the mid-19th Century. It was an astonishing technical achievement in its day, but central Ireland was perhaps not the best place to site it. The cloud cover rivals Kendal’s!

Lastly Carol Grayson showed us how she had managed to capture two unusual optical highlights on the Moon, the Lunar X and the Lunar V. In both cases, these are the result of the way the oblique sunlight hits the mountains and crater ridges as the Moon turns, and they can only be seen quite briefly.

Liz Hodgson

PANSTARRS passes the Plough…

PANSTARRS path Apr 24 - May 18 small

If you fancy an observing challenge over the coming few weeks, there’s a faint comet drifting past the stars of The Plough. Visible in small telescopes and large binoculars at the moment, Comet PANSTARRS K1 is being observed and photographed by comet watchers around the world, and I’ve managed to capture it with my DSLR, so why not give it a go? Full guide on my blog…

http://waitingforison.wordpress.com/comet-c2012-panstarrs-k1/

Worth getting up at Stupid o’clock for…

Asrtronomy can be a very anti-social hobby, and that’s never truer than at times like this, when all the “good stuff” is visible in the wee small hours and an intrusive big bright Moon means you only have a small window of opportunity, just before the sky starts to brighten, in which to see or do anything useful. Which is why I got up at 3am on Friday morning, grabbed my camera gear and tripod, and headed out to my nearby dark sky oasis, a woodland clearing at the foot of Kendal Castle, to try and photograph the Milky Way, Mars, and a comet…

Often when I do this I arrive at my observing site to find that while I’ve been walking the clouds have rolled in, covering everything, and I have to trudge home again without a single new photo on the memory card. Thankfully on Friday morning the clouds stayed away, and I was able to tick off everything on my astrophotographic hit list…

Should note here that all these photos were taken with the most basic set-up – my entry level Canon digital SLR, mounted on a tripod, fitted with a fast or wide angle lens and set at a high ISO (what we used to call “film speed” in Ye Olde pre digital days!) taking time exposures of several seconds, which were then combined together (or “stacked”) to create a single more detailed image. One of my friends from the Cockermouth AS very kindly made me a mount last year which will allow me to track the stars, but I have yet to use it because I’m saving it now for nights when the Milky Way is dominating the sky.

Ok, here’s what I managed to take. I try to take pictures which are attractive visually as well as interesting astronomically, so I hope even if you’re not into astronomy you’ll like them. Click on the images to enlarge them…

The Milky Way rising over the treetops…

m way s

Mars (right) and Spica sinking lower as dawn approaches…

Mars spica s

The Milky Way around the bright star Deneb…

NA Neb2 s

The constellation Lyra…

lyra s

And finally, comet Panstarrs K1, which is still very faint but might get brighter in a while…

panstarrs close up circle

Yes, definitely worth getting up at Stupid o’clock for…