Archive for July, 2013

Brew and Slew on a pleasant summers night

Blog Friday 12th July 2013

 

Although the weather has been exceptionally pleasant across most of the UK for the past week or more when darkness falls it has tended to cloud over, get very hazy or event misty. I have gone to bed on a number of evenings, setting my alarm for just past midnight, but awaking to a starless sky. Last night things were different, thankfully. I arose at 00.15 local time, brewed some tea and had the observatory open by 00.30. It was a rather lovely sky, the milkway stood out proudly, with many stars showing, the SQM registered a respectable 20.35 when pointed at Aquila.

 I only had one target in mind; others would come after some page turning I was quite sure. The target I wanted to catch up with was a galaxy in Aquila, NGC 6814, this is the only galaxy that I’m aware of in Aquila, there maybe more, but I guess they will be faint! It was reading Sue French’s latest S&T ‘Deep Sky Wonders’ that brought it to my attention. I located the mag 11.2 nearly face on spiral after a slow star hop from the scopes parked position. I was again running x2 Watec video camera, one on the 6” refractor, the other on the 20”. The image on the monitor from the 6” only showed a grainy smudge of the galaxies ghostly outline when all the camera controls were turned to max! Field stars showed up readily but the galaxies diffuse outline was a challenge. As you would expect the 20” fared somewhat better but still only showed partial detail with strong hints of arms and spiral structure. I copied what I saw on the monitor screen faithfully in my sketch, noting the stars ‘embedded’ in the galaxy, as always hoping one maybe a SN ;¬)

NGC 6814 partialy yielded to the 20" mirror and Watec video camera combo

I had hoped for a more dramatic view and was somewhat disappointed, but hey that’s astronomy! Close by was ‘The Little Gem’ planetary nebula, familiar to me from observing sessions with various telescopes at Kelling Heath star parties, but at the time of writing I’m unsure if has been sketched by myself? The images on both monitors from both 6” & 20” were immediately impressive, I had anticipated an over exposed stellar looking ‘blob’ resembling a bright star, but no, this was as impressive as the previous galaxy had been disappointing to me 🙁 There was considerable amount of mottling with dark lanes visible, especially pronounced running N-S through the centre, some areas where distinctly brighter a curved region to the east, in from the edge looked somewhat like a shell layer, perhaps? I fiddled with the camera settings on the 20” Watec, along with the monitor contrast and brightness settings, switched off all lighting in the room and pulled back from the screens, studying the images intently for a considerable while before I put pencil to paper, as seeing came and went I noted a central star appear and disappear, strangely both cameras/scopes showed this (certainly a seeing thing then). When I came to make my drawing I put the central star in, even though it was fleeting. The only images I had in the observatory just showed a uniform, solid disc, often how CCD chips overexpose on brighter compact objects. I had no internet connection so was unable to verify either the central star of detail I had drawn in. I made both a PN with field star sketch out to a fov of approx 11’ x 11’ and a more detailed circa 3’ fov sketch. It wasn’t until the next morning when I was able to scan the sketches in and invert them that I was able to compare them with detailed images from the web. To be honest I’m pretty delighted at the time of writing with the match 🙂

NGC 6818 the 'Little Gem'

 

'Little Gem' detail sketch

 

 

See what you think? I closed up around 2am local time, returned to bed, took ages to drop off to sleep and awoke reluctantly a few short hours later to the rude alarm clock!

Dale

Hot & steamy with a new cooled camera

Blog 4th, 5th & 6th July 2013

 

I have just take delivery of a ‘new’ Watec video camera; well new to me that is, it is a cooled version of the newer of the other 2 Watec cameras I already own. A 120N+ with a modified case, heat sink and fan added externally with a thermostat controlling and a minute red indicator light which doubles as a cooling on/off switch on the top. This has been sold for a number of years in the US as a Stellacam 3, there are still a few available from Cosmologic who do the authorised upgrade, however Watec have discontinued this camera and are not intending to replace with a later model sadly, likely down to the fact that video astronomy is a rather small niche market. I obtained the camera thanks to Martin Lewis whom I approached as a representative of the West of London Astronomical Society (WOLAS) whom I knew had one of these cameras and sadly like many societies don’t make use of them. My assumption proved to be correct and I was able to purchase the hardly used camera with a few basic accessories for just over half the original price.

The new cooled Watec 120N+ deep sky video camera

 

Thursday 4th July

So as you can imagine, I was keen to try out the new camera! Tonight gave this opportunity, we are currently experiencing something of a ‘heat wave’ here in England, with it has come clear if somewhat hazy night skies. My first public harmonica playing at a ‘jam’ session in a town 13 miles to the south of Chipping, saw me up late on this night and buzzing from the performance experience in no hurry to go to bed.

The sky was poor so I knew it wasn’t a night for trying to get deep so I tried the camera on a few bright stars to start off with until I got focus sharp and then I progressed onto M71 in Sagitta and then onto the ever popular M27, both being bright I had the camera sensitivity turned right down and was pleased at how ‘clean’ the image was when compared mentally with the standard camera. I tried it on a mag 11.9 spiral but the image of a more diffuse object was appalling in the thick haze, making pursuing such objects tonight to be totally pointless, but at least I had first light if no sketches!

Friday 5th July

I took a few hours owed from work and came home early meeting up with my pal Es Reid who helped me give the telescopes a bit of a cleanup (optically) and set all 3 Watec cameras up, the new cooled one on the 20”, the 120N+ on the 6” F9 refractor and the original limited exposure 120N on an old 5” F4 home built refractor attributed to Jim Muirden. The control unit multi pin jack plugs have worn rather loosed giving poor connectivity and image jitters, Es tweaked these improving the situation, testing the cameras, power supplies and BNC cables ensuring all were functioning well, we then tied up the cable bundles to ensure lack of movement during operation so hopefully little strain will be put on the rather delicate ‘back ends’ of the cams in future. Es scuttled off home at 5pm and by that time it looked as if I was going to get to try out our afternoon’s handiwork, this wasn’t to be as the haze virtually obliterated even the brightest stars as the sun went down.

Saturday 6th July

Returning home from an all day 50th birthday party at 10.30pm under a clear sky gave me an opportunity to get a little observation in that resulted in a little sketching, it had been a scorcher of a day hitting around 30 deg Feraheiht . I ended up viewing and sketching a couple of low targets down in Sagittarius which was well placed, if not well presented being very hazy and rather bright sky wise at SQM 19.5. My first sketch is of Messier 21 an open cluster that was missing from my Messier folder. I was running both the un cooled 120N+ Watec camera, and the new cooled one, the former on the 6” refractor and the later on the 20”. The 6” gave a larger fov so I sketched that view of this open cluster which lies very close to the Triffid nebula M20 as this image from friend David Davis shows

Messier 21 can be seen to the upper left of the striking Triffid Nebula M20

What I liked most about M21 is the lovely circular asterism of stars above the knot of brighter central gems, very pleasing.

Open cluster Messier 21 in Sagittarius

Next the new camera got a workout at last, as it was so hazy I stuck with brighter objects opting for a tiny globular cluster in Sagittarius that lies less than a degree from the stunning M 22. This diminutive globular is at a distance of 25,000 LY’s, which is 2.5 times farther than M 22, yet, M 22 appears 21x larger through our telescopes! NGC 6642 is not just farther away, but smaller and fainter.

Distant and small NGC 6642

And so to bed, pleased to have got a couple of all important sketches done and used the new camera to good effect.

Dale

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