Dubai Observations – Friday 28 September 2012

Back from a holiday in Dubai and Oman. I had a great time and most evenings I managed to get some stargazing in while there. I’ve a bundle of notes and sketches scribbled on hotel notepads. Over the next few days I’ll be writing my observations up and posting them here. I took my Celestron Skymaster 15×50 binoculars with me and a tripod so observing was with those or naked eye.

Location: Dubai, Souq Al-Bahhar, Mall of the Emirates hotel.
Weather: Hot.
Equipment: Naked eye, Celestron Skymaster 15×50 binoculars
Highlights: Summer Triangle, Vega, rotation, moon, Jupiter, Venus

23:00 Sitting eating our evening meal at the Souq Al-Bahhar opposite the Burj Khalifa in Dubai. Just watched the Dubai Fountain show in front of a lit up Burj. With the naked eye to the left of the Burj I can see a star. It must be a bright one as there’s a huge amount of light pollution around here and it’s not easy to see any. A quick check on Sky Safari on my iPhone confirms my suspicion that it’s Vega.
So, that fainter one I can just make out to the left of it must be Altair, and so the one above must be Deneb. Once again I’ve found my familiar signpost – the Summer Triangle.
But now the strange thing. It’s all rotated about 30° clockwise to what I’ve become used to. I need to work out and understand why that is. I was used to Vega being at the top of the triangle through the Summer back home. Here it’s Deneb. Is that because we’re at a lower latitude or is it just because it’s a few months on from when I was observing it back home? I haven’t thought it through yet but that probably makes sense as we’re about 30° further south at 24°N (Home is 52°N.)

Incidentally, I was looking at the moon earlier, through the binoculars through the hotel window, while A was getting ready to go out to eat. It was almost full. Below Tycho I could make out some edges of craters along the terminator.
I was noticing that curve of the terminator is at a different angle to back home. I think this is for a different reason though. I seem to recall listening to an Astronomy Cast podcast that explained that.We were out by the Creek just before sunset, on the roof of the Sheikh Saeed Al Maktoum House. The setting Sun was low, perhaps 15°, to West. Meanwhile the Moon was just becoming visible to the east, at about the same elevation.

Anyway, meanwhile back at Burj Khalifa and the Dubai Fountains. We left through the Palace Old Town hotel and whilst waiting for a taxi spotted Jupiter. It’s the brightest thing in this sky apart from the Moon, the planes, the crazy buildings….

Next morning was an early start to get a flight to Oman. From the taxi to the airport I caught a brief glipse (again naked eye) of Venus just before dawn and saw the Sun rise between the buildings to the East of Sheik Zayed Road.

Summer Triangle Widefield Imaging – First Attempt

At mentioned in my last post, I ended up with 263 frames of the Summer Triangle. I thought I’d have a go at processing one of these to see if I could get more detail out.

So here’s my starting image.

I hadn’t realised quite how bad my light pollution was until I saw this.
It’s a 30 second exposure, sunlight white balance at ISO400 taken on a Canon EOS400D with a Sigma zoom set at it’s widest 18mm focal length.
faintest stars you can see here are about magnitude 4.
I then tweaked it a bit in photoshop, adjusting levels to bring out fainter stars up to about magnitude 7. I removed the colour cast as best I could, although I think I went a bit too at as it’s quite blue now.

Now I know this is far from perfect. It’s a first attempt and I can see quite a few problems.
Stars aren’t quite in focus. I’d focused manually and it’s difficult to know in the dark through the camera eyepiece.
Next time I’ll lock the mirror up to prevent that causing a bit of shake.
Exposure is only 30 seconds but I don’t think I can do longer without the stars blurring with motion. I could, if I put the camera on the telescope’s mount. There is a piggy back mounting screw.
I think I need to really up the ISO, perhaps up to 1600 to captured the fainter stars. I’d held back because I thought I’d end up overexposed with all the light pollution. I think though, that I can fix that with levels in processing.
I need to investigate stacking multiple images too, as that seems to be how many people do it.

Finally I annotated the final image in Skitch on the iPad to identify the various constellations and stars. That was an fun and educational thing to do. I hadn’t noticed the small constellation Delphinus creeping in just below Cygnus for instance, and on zooming in and around the shot, I also noticed Collinder 399, Brocchi’s Cluster aka the Coathanger sneaking in.

Observations – Saturday 4 Aug 2012

Location: Worthing, in-laws back garden
Weather: mixed cloud. Moving quite quickly so changing opportunities. Dry.

22:00-ish First light on the new Skywatcher 9×50 RACI finder scope. It’s great-so much easier to use than RDF. You can see so much more. In fact I’m thinking it’s worth taking away with me when travelling. Even though i know where it is now, I was on the Ring Nebula, M57 within minutes.
Yeah, yeah, I know M57 again but I wanted to see if a couple of other factors improved the view. Firstly there is far less light pollution in Worthing, their street lights aren’t so orange, and being on the coast there is half the amount of light anyway. Well until the moon came out. More on that later.
Secondly I’d been to Sussex Astronomy Centre and bought a new eyepiece. I got a Skywatcher 6mm ultra wide eyepiece with 66deg APOV (apparent field of view).
M57 was really clear in it. I could really see the ring and the darker centre. I could also see that it wasn’t uniform all round.

Father in Law came out to see what i was up to at this point, so I moved on as this is perhaps a tricky target if you’ve not looked through a telescope before. So I showed him the double Albireo in Cygnus. The difference between the brighter yellow and it’s blue companion was very pronounced.

23:00-ish Then my Mother in Law came out, together with a lot of cloud so all I was able to show her was Vega directly above in Lyra and a few stars around it.

23:30-ishThey went in and my Brother in Law came out as the moon was clearing the trees. About two days past full. It was washing out much of the sky and reflecting off clouds and I think the sea a couple of streets to the south.
Had to put the moon filter on to cut the brightness and we went straight for the 6mm. Seeing was good. Hardly any rippling. Put the tracking on and observed along the terminator. Highlights were Mare (Lunar 100 #10) and the adjacent Cleomedes crater and a chain of 4 craters including Langrenus, Vendelinus, Petavius and Furnerius. Of these Petavius (Lunar 100 #16) was the most impressive with it’s central peak.
Takes my Lunar 100 count up to:
Observed 3/100
Imaged 8/100

24:00-ish. popped the Asda webcam into the eyepiece holder and fired up Sharpcam on the netbook to snap a couple of shots of the moon.

Mare Criseum and Cleomedes crater.

Craters on the terminator. You can see the central peak in light and shadow on Petavius