Archive for the 'Observing Reports' Category

Observing Report 3rd January 2010 (Quads workout)

Posted by on January 4th 2010 in Observing Reports
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After having had the weather spoil most of the meteor events of 2009 I was hopeful that the clear skies of the current cold spell would permit a reasonable view of the 2010 Quadrantids. Late in the afternoon the skies darkened and the clarity was good, so I prepped for a 2-hour session to start at 18:00.

The view northwards from the top of our plot is reasonable, looking out across dark gardens and a large low retirement-home.  The radiant was just visible above the artificial horizon, so there was a fair chance that I'd be able to see most of the upper 180-degree arc of the display. Doing some rough maths I figured that if the peak rate was 120/hour I'd get a reduction of 50% due to the 180-degree restriction and a further 50% reduction due to the low elevation. If all went well, I'd be looking for 30 meteors during the 18:30 - 19:30 peak hour.

18:00 arrived and I set up the camera. Despite having taken it outside early to acclimatize, the internal optics hazed up within minutes due to the low temperature (-4C and falling) so pics were a no-no. I've an aversion to forcing heat into any camera, so I took it back indoors for a gentle rewarm and resigned myself to a visual-only session. I found myself a comfy place from where to watch.

As the minutes passed the horizon became a hazy yellow mess due to a combination of a thin fog and light-pollution from the local street-lights and from the retirement home. Seeing 30 meteors in the next hour was going to be a challenge.

The show started at 18:46 - a trail straight through the head of Draco. And another a minute later, this time up near Cepheus. Things were looking good, but then it stopped. I saw only one more trail - a gloriously-bright streak almost overhead, passing through Cassiopeia at about 19:20.

In summary, the show wasn't much of a success, but it was good to be out again, despite the biting cold.

The next half-decent show should be the Lyrids in April, active from the 16th to the 25th with peak activity on the 22nd. Hopefully there'll be better conditions allowing me to get some pics as well as views.

Observing Report 6th-7th December 2009 (Moon bits)

Posted by on December 14th 2009 in Astrostuff, Observing Reports, Pics
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Sorry, this is a bit late...

Sunday evening was forecast to be cloudy. I wasn't planning to get out to the obsy but seeing as the sky was almost clear late on I took a chance and got set up to observe the Moon and possibly get some webcam footage.

The seeing wasn't brilliant but there was plenty of detail to be seen. After an hour or so of crater-hopping with the 3.5mm Hyperion eyepiece I changed the setup and got stuck in with the webcam, getting some reasonable data during the small hours. Registax-processed results as follows:

Clavius (136 miles dia.)

 On the right, working downwards: Abulfeda (38 miles dia.), Almanon, Geber, Azophi/Abenezra/Abenezra C

Tycho (52 miles dia.)

Vallis Alpes (79 miles long, 7 miles wide at maximum)

Just in case you don't know your way around up there, here's some help:

Before you ask, no, I didn't take this pic.

Observing Report 10th-11th December 2009 (Frosty Mars)

Posted by on December 13th 2009 in Astrostuff, My vids, Observing Reports
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The weather here on Thursday evening was a bit odd - periods of thick fog alternating with cold clear spells. I got the scope set up early and while waiting for the longer clear bits I used the odd short bits of good visibility to get good focus and tracking. Oh, and to fight the battle against condensation on the kit.

Some time after midnight the fog lifted and everything was clear and still, not a breath of wind and the seeing was brilliant. All of the condensation froze within minutes. Undeterred by the layer of ice on the kit, I had a good look at Mars before nabbing some webcam footage of it. Visually, I'd never seen it so good - the polar cap was really bright and the planet was almost motionless, unlike the previous Mars session when the thing was moving around like a demented Morris Dancer. I spent a good hour or so just studying the surface detail, something I've never been able to do before. Here's some of that webcam footage after selecting a 256x256px region of interest around the planet:

Soon it was time to move on. I changed the eyepiece setup and this caused some melting of the ice on the kit. Figuring that it would be best to let the temperature settle down a bit I nipped in for a cuppa and then sat outside for twenty minutes watching a fair few meteors blazing across from East to West - they were mostly Geminids but there were a few others up there. I did contemplate setting up the D50 with the 35mm prime in order to get some images, but the camera was by now well-frozen and I wasn't going to risk trashing the mechanics inside the lens.

When all was settled I slewed the scope around to Saturn, which had risen to a reasonable height above the horizon. It looked a bit dimmer than I've seen it before but I could still see the rings, not far past being edge-on. A couple of dim moons were visible but not much else. I grabbed a fair few avis with the webcam but they didn't look much good.

After another half-hour of visual, watching Saturn and some more meteors, the fog returned. This time it was thick, freezing, and obviously here to stay. I ended the session and closed the obsy roof. The next hour was spent mopping up meltwater from the kit and from the underside of the roof. I returned to the house at 06:00 vowing to get a cheap dehumidifier in the post-Christmas sales.

Anyway, I did some preliminary processing of the Mars data and sent the pics to a learned friend. He's confident that he's identified the surface features correctly, and pointed out the tiny clouds in the vicinity of Olympus Mons. He also reckons that the colours are fine, but I'm not so sure:

 

 

Again, you'll have to wait for me to find time to process the Saturn data.

I'll finish with a reminder - don't forget that Geminid meteor shower.

Observing Report 21st-22nd November 2009 (Mars at short notice)

Posted by on November 24th 2009 in Astrostuff, Observing Reports
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Saturday evening was forecast to be cloudy and wet, and I was resigned to an evening of avoiding Strictly, Casualty and the rest of the Beeb's prime-time twaddle, but the forecasters got it wrong - just for a change there was more gap than cloud. I grabbed my chance and cranked-up the obsy.

At such short notice I'd not had much time to think ahead, so, as the Newt's cooling-fan purred away, I sat back and looked up for inspiration. Rising in the East was Mars, and just for once it looked fairly bright. Target acquired!

After the scope had been cooled and the collimation checked I slewed it around to Mars and set about trying to get a decent focus - not easy, as the scope was dancing around in the wind, sending the image dancing all over the webcam chip. After a quarter of an hour of this malarkey I was happy with the focus and set about grabbing some .avi data. While this was going on I was on the lookout for Alpha-Monocerotid meteors - a minor shower that peaked on the 21st. I managed to spot a couple of them and a few sporadics as well, but didn't have the dSLR set up so there are no pics. 

Most of the webcam runs had some blurring and fading due to clouds and hence got consigned to the Recycle Bin, but some were OK. By about 03:00 a full cover of cloud had rolled in and spoiled the show so I closed the roof, had a cuppa and started processing the data. I figured that the night had finished so I parked the scope and packed away.

Leaving the obsy at 04:00 I looked up again and all was clear, so I did a smart about-face and went back in. Half an hour later I was set up again and looking at Saturn for the first time in ages. I grabbed a few .avis before the clouds spoiled things again, and this time there was some drizzle so the session was definitely finished.

After a couple of hours of kip I finished processing the Mars data, ending up with some rubbish and a few decent images. From these I've made a composite image just to see if there are any noticeable differences due to processing or planetary rotation. For an explanation of what's what, see the text below the pic:

 

Upper images from a 7200-frame avi taken at 02:08 - left: best 10% of frames stacked, right: best 90% of frames stacked.
Lower images from a 7200-frame avi taken at 02:20 - left: best 10% of frames stacked, right: best 90% of frames stacked.

Damned if I can tell any difference between them!


I'm quite pleased with this - it's by far the best Mars image-set that I've done to date, not bad for a cheapo webcam. I'm inspired to get some better data later this month when Mars is a lot higher in the sky.

As for the Saturn data, I've not yet found time to process it properly. First impressions are that the data's not worth the effort, but I might be tempted to have a whack at it. If I get anything worthwhile, I'll let you know.

 

And now for the rest of the astronews...

Followers of this blog will know that I'm a keen meteor observer, and they may be wondering why there are no observing reports here about the recent showers. Well, the weather's the main culprit...

The Orionid shower  peaked on the 21st of October. I managed a short visual session during the preceding evening when all was clear for an hour or so, and managed to spot four Orionids, but the main night was clouded out. Typically it was much clearer the night after too, but I was too busy to get out. It was a similar story with the Leonid shower on the 17th of November - clear the night before when I spotted about ten Leonids, and then cloudy and rainy for the main night and for the rest of the week.

Let's hope for a break in the weather around the 14th of December for the Geminid shower, which is always a good display.

Observing Report 24th-25th October 2009 (M35 target practice)

Posted by on October 27th 2009 in Astrostuff, Observing Reports, Pics
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At last - a more-or-less cloudless night. It was a chance to have a look through the new frac and to try out a few new tactics.

The first thing to do was to get the frac lined up with the Newt so that they were both looking at the same thing. Using Starry Night Pro and the ASCOM/EQMOD setup to control the mount meant that finding a suitable target was a doddle. I settled for Betelgeuse, the bright Red Giant forming the left shoulder of Orion. After a minor tweak to get it in the centre of the Newt's FOV, I adjusted the other scope and the two finders so that it was central to all.

Next up was my first attempt at web-cam autoguiding. The software of choice for this was PHD, as it was recommended by several folk that I've quizzed about the subject. The webcam was another Philips SPC900NC, famed for its ability to get good images in near-darkness due to the high-quality Sony CCD. Although the process was new to me, it was simple enough... slap webcam into frac, find and focus on a suitable star, press the "Start" button and that was it - it's self-calibrating and sends pulse-guiding signals via the ASCOM/EQMOD setup so that there's no data conflict. Beyond all expectations, it worked first time, so I was pleased about that.

Then it was time to find a suitable target for a test image. I didn't want to go for a complex victim like a nebula or galaxy, as I wanted to be able to examine the star-images to check for trailing and guiding errors. After scanning through lists and across the sky, I chose M35, an open cluster in Gemini, as it was high in the sky and would allow a decent period of time for the exercise.

So then it was time to go for it. I slewed the Newt to centre on the few visible stars of M35 and then adjusted the frac to find a guidestar, hit the buttons and let it go. Using the D50/MPCC combi in the Newt, I set the laptop to take a series of light and dark exposures of varying duration, went inside to make a brew and then sat outside skywatching in the strengthening wind. Aside from a couple of bright and unexpected meteors speeding over from the East, there wasn't much activity visible to the naked eye, but the binoculars revealed much more. Time was well-spent gazing at Orion's nebulae, The Pleiades, Andromeda and a few other familiar objects.

After the camera had finished with M35 it was time for a change. Mars was now within sight low in the East, so I slewed to that and had a good look around. The gibbous phase was obvious, but other than that it was hard to see anything as the wind had become so strong that it was deflecting the scope so much that the image wasn't stable. I did set up to catch Mars on the original webcam via the Newt, but didn't get any data because the target was moving off-chip due to the blowy conditions. After a few minutes of frustration the sky clouded over and that was it for the rest of the session.

In all it was a good exercise. Guiding sussed, first-light for the frac and some frames of M35. The following day I chugged through the images to cull all of the longer exposures, as they were blurred due to wind-shear. After that, the laptop was busy processing the remaining data, and eventually it spat out this:

M35 (NGC2168) in the centre, NGC2158 to the lower-right.
45 light and 45 dark frames restricted to 60 second exposure times due to wind-shear.
55 light and 55 dark frames with exposure times up to five minutes were considered unusable.

 

Despite the dumping of most of the frames it seems reasonably good to me, seeing as it was done for process-checking rather than as a pic for the mantelpiece. There's a bit of star-elongation due to wind-shear, but there are hardly any errors visible due to guiding, which is what I needed to know. Next time out I might try for some decent pics of this pairing, as there's something quite appealing about the arrangement, with the combination of newer blue and older red stars.

If you've a mind to go out looking for this target, here's a rough guide:

Finding M35

Observing Report / Lens Test 22nd September 2009 (Big Dubyah)

Posted by on September 23rd 2009 in Astrostuff, Observing Reports, Pics, Shiny new kit
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I'd not planned to go out observing, but there was an hour or so of cloudless sky yesterday evening and I had a little time to spare. This was an opportunity to sky-test the Nikon AF-S DX NIKKOR 35mm f/1.8G lens to assess how well it is suited to taking widefield pics of the night sky.

In particular I was looking to see:

  • how much sky would be captured in the frame;
  • if a reasonable focus could be achieved using the camera's auto setting;
  • how quickly the camera sensor would become saturated at f/1.8 and ISO 200;
  • how much vignetting would be caused by using a 52-48mm step-down ring and Light-Pollution filter;
  • how much coma would be present at the edges and corners of the image; and
  • how much star-trailing would be caused when using a static tripod as opposed to using a driven equatorial mount.

The challenges would be to see if I could find a reasonable exposure time, get a small number of images for stacking, and then process-out the vignetting, star-trailing and any light-pollution.

Jupiter was in the southern sky so I pointed the camera at it to get the autofocus set. I then turned off the autofocus and fixed the position of the lens focus ring by the judicious application of duct-tape.

Next, I pointed the camera at the Cassiopeia / M31 Andromeda area and took a few test-frames of various durations. Eventually I settled on an exposure duration of 30 seconds and took 12 pics.

These were stacked in DSS and hurriedly processed in PSCS3, and here's the result:

Mouse-over the pic for details, click it for a bigger pic.

 

I have to say that I'm quite impressed with the raw images that this lens produced. Shooting with the aperture wide open captured a lot of light, and for a change I had to tone down the details rather than go through the usual routine of having to drag the details out of the murk. I'm damned if I can find any coma in the raw frames, which means that there'll be no need to crop off any bad areas. The expected vignetting was dealt with in PSCS3, the compensation isn't perfect but to be fair I've only done a quick fix, no doubt I could get it better if necessary. The amount of star-trailing was acceptable, and I'm confident that I could get it processed out if necessary and if I had enough time.

And the framing? I'm happy with it for targets the size of Cassiopeia, but the capture-area might be a tad small for meteor-work. Time will tell - between now and the end of the year there will be plenty of opportunities for snapping a few meteor trails (more on that in another post very soon (but don't hold your breath)).
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