chromosphere » astroimaging

Circumzenithal Arc

Graeme Coates — Mon, 18 Aug 2008 15:56:01 +0000

Saw this circumzenithal arc on Friday 15th from Abingdon. Looks much like an upside down rainbow above the sun (which needs to be lower than 33 degrees or so for this to occur) – it occurs due to horizontally orientated ice crystals high in the upper atmosphere.

Only had the camera on my phone so the image is a bit ropey, but hopefully clear enough…

M42, M43, NGC 1977 – The Orion Nebula and Running Man

Graeme Coates — Tue, 18 Mar 2008 13:23:51 +0000

RA: 05h 35m 17s, Dec: -5°23’28″
The Orion Nebula (M42 (NGC 1976) & M43) is located in the “sword” of Orion and is a large emission nebula that is easily visible to the naked eye. It is an area of star formation – the closest such to Earth at a distance of 1500 light years. The nebula is an estimated 30 light years across, and contains a young star cluster (the Trapezium) in the bright core of the nebula. The reflection nebula at the top of the image is the “Running Man” nebula (NGC 1973, 1975 and 1977) – so named due to the resemblance of the silhouetted dust lanes.

I had lots of trouble with this image (taken on 6th Feb, 2007) – the flats I took didn’t work out (there’s the odd artifact here and there!), and I’m not quite happy with the colour balance – have another go at this later I think…

NGC2264 – The Cone Nebula and Christmas Tree Cluster

Graeme Coates — Tue, 18 Mar 2008 13:20:48 +0000

RA: 06h 41m, Dec: +9°53′
The Cone Nebula and Christmas Tree Cluster are part of a larger star forming complex within the constellation of Monoceros. A 2.5 hour exposure in H-Alpha light taken 22nd December 2006 using an Astrodon filter shows only glowing hydrogen gas and stars – the blue reflection nebula near to the “Fox Fur” nebula (below the bright variable star S Monocerotis) often seen in photos of this region is largely invisible as most light is of the wrong wavelength and is rejected by the filter.

NGC2244 – The Rosette Nebula

Graeme Coates — Tue, 18 Mar 2008 13:17:04 +0000

RA: 06h 33m 45s, Dec: +4°59’54″
The Rosette Nebula is a large H II region located in the constellation of Monoceros, just to the left of Orion. The nebula is a large star forming region with a cluster at the centre that , through the action of the stellar winds, has blown a large cavity out of the nebula from which it formed. The nebula itself is often referred to simply as NGC 2237 (though NGC 2238, NGC 2239 and NGC 2246 are all parts of the same nebula). The cluster is designated NGC 2244.

At 100% scale, the detail in the Rosette Nebula (showing the dark regions obscuring the bright emission nebula in the background) shows the effects of the stellar winds from the hot stars of cluster NGC 2244 (top right). This is a crop from the full size image above.

Lunar Eclipse of March 3rd 2007

Graeme Coates — Sun, 02 Mar 2008 13:13:45 +0000

The lunar eclipse of the 3rd March 2007 brought clear skies and good conditions across much of the UK, with only some thin high cloud arriving in Oxfordshire towards the end of the eclipse. Maximum eclipse occured at 23:20:56 – ideally timed for the UK.

More recently, on the 21st February, 2008, another lunar eclipse was visible from the UK and Europe early in the morning. However, the weather for this event was not as favourable with cloudy conditions across much of the UK (despite having a long period of clear weather in the preceding week!).

There will not be another lunar eclipse visible from the UK in its entirity until 2015 (though two will be partially visible with the eclipsed moon setting on Dec 21st 2010, and the eclipsed moon rising on June 15th 2011).

Here are some of the best images from the eclipse (if you view the gallery, make sure the post has the full width of the page to see it all – clicking the expand button or viewing the individual post):

[Show as slideshow]

Solar H-Alpha Imaging Round Up

Graeme Coates — Fri, 15 Feb 2008 16:05:10 +0000

Continuing in the migration of my old site, here’s a post with a round up of my best h-alpha solar images. For a while, I owned a Coronado Solarmax 60 with BF15 blocking filter which I used to use on my Takahashi FC60NZ – I traded this more recently for the FLT110 – I found that I really wasn’t getting to use the h-alpha equipment for most of the year (work gets in the way when the sun is up!).

The h-alpha filter works by using an etalon to restrict the wavelengths of light as viewed through the telescope down to only a small region of the spectrum around 656.3nm (typically with a bandwidth of <0.7Å), which is a principal emission wavelength of excited hydrogen atoms (for the transition n=3 to n=2 in the Balmer series). This allows features such as prominences, flares, filaments and active regions to be observed, whereas in white light these are often not as noticable or are invisible.

My images were taken using either a Toucam Pro II webcam (for the closeups), or using the SBIG ST2000XM coupled with a Denkmeier Part O/Cell #150 relay lens combination to give the system enough backfocus to bring the camera to focus on the Takahashi FC60NZ. Note, for those of you with an SBIG camera taking very short images (milliseconds), you’ll want to check out SBIG’s Article on Vertical Streaking (.pdf)- you need to adjust a potentiometer in the back of the camera to avoid this happening!

The following gallery is a collection of images taken using the Coronado filter – there are more images of the sun in h-alpha during the 2005 Annular Eclipse.

[Show as slideshow]

Equipment Woes and a Crescent Moon

Graeme Coates — Mon, 11 Feb 2008 09:42:57 +0000

So the weekend just gone has had fabulous weather here in the UK – sunny, warm (for February!) days, and cold clear nights – and so I thought I’d try to setup my imaging kit to have a go at some astronomy for the first time since April 2007, and also as a bit of a dry run before the Kelling Heath star party in April. I even managed an image of the moon – 30 images using the ST2000XM on the FLT110, processed in Registax – click the image above to view it!

Of course, nothing goes smoothly:

CCD dessiccant had (long) expired and when bringing the chip of the CCD down to temperature (-25°C), ice formed all over the chip. Solution: Bake the dessiccant canister in the oven for 4 hours at 175°C and then reinsert and let it dry out – I’m still waiting for the dessiccant to do its thing – I may even have to bake it again tonight to get it dry.
Focuser issues – This is so far unresolved – think it’s gonna need fixing as I can’t connect to it.

However, all was not completely lost. I adjusted the RA worm clearance on the Titan (much less backlash, but still loose enough not to bind and fry the motor), and I installed a demo version of PemPro to look at the periodic error on the mount. This measured out as about +7/-5 arcsec uncorrected, and with a very quick run through, I was able to get it down to +/- 2 arcsec. This is an excellent piece of software, and one I think I will be buying in the future – not to mention its ability to help polar alignment, and backlash correction settings.

M65, M66, NGC3628 – The Leo Triplet

Graeme Coates — Fri, 08 Feb 2008 09:26:54 +0000

RA: 11h 19m, Dec: 13°15′ (approx. centre)
The famous Leo Triplet is a small group of three spiral galaxies (namely, M65 (NGC3623 – bottom-left), M66 (NGC3627 – top-left) and NGC3628 (right)) that is located about 35 million light years away between Theta and Iota Leonis. All three galaxies are readily visible in a small telescope, though NGC3628 tends to be the hardest of the three to spot. Additionally, the smaller galaxy NGC 3593 (not shown) may also be a member of this group.

This image was taken from the dark skies of Mid-Wales on December 21st, 2006 as a “quickie” before sunrise after a run on imaging the Cone Nebula (to follow in a later post) – it’s only about an hour of total exposure. A much longer imaging run would allow the faint surrounds of M66 and the “tidal tail” of NGC3628 to be brought out, but unfortunately, as is so often the case with imaging in the UK, the clouds came in for the next 5 nights leaving the telescope ready to go, but unable to actually take an image…

M81 & M82 – Bode’s Nebula and The Cigar Galaxy

Graeme Coates — Thu, 07 Feb 2008 23:06:09 +0000

RA: 09h 55.5m, Dec: +69°20′ (approx centre)
M81 and M82 in Ursa Major are two of the brightest members of the M81 group of galaxies. M81 (often called Bode’s Nebula after being discovered by Johann Elert Bode in 1774) is a large bright spiral approximately 12 million light-years distant, whilst M82 (the “Cigar Galaxy”) is an irregular starburst galaxy, highly disturbed by gravitational interaction with other members of the group.

This was taken from Kelling Heath at the 2007 Spring Star Party on an excellent night after we had been fogged out for the previous two nights! I’m hoping to go again this year to do some more imaging…

In the region of M81 and M82 (and across large parts of the northern sky), there is a large faint nebular complex associated with dust and gas expelled from the plane of the galaxy. The region here is part of MW3 (Mandel-Wilson Catalog of Unexplored Nebulae) and the faint dusty areas show up faintly in a strongly stretched image of the region. This has been refered to as an “Integrated Flux Nebula” since it reflects the galaxy’s light rather than that of a single star. Also visible is Holmberg IX (below M81) which is a small, faint blue irregular galaxy also in the M81 Group.

M31 (NGC 224) – The Andromeda Galaxy

Graeme Coates — Thu, 07 Feb 2008 22:47:30 +0000

RA: 00h 42m 44.3s, Dec: +41°16′ 9″
The Andromeda Galaxy is a naked eye object from a dark site, appearing as a small smudge in the sky. Long exposures reveal it’s true extent (over three degrees in size!) as well as two smaller elliptical companion galaxies (M32 – top, and M110 – bottom edge partially off frame). It is a member of the Local Group of galaxies, and is actually moving towards us at a rate of about 300km/s. Taken from Abingdon, UK on the evening of September 21st, 2006.

This picture was chosen as Anacortes Telescope & Wild Bird picture of the day on 6th Nov 2006.

Additionally, it was chosen as Sky at Night Magazine Hotshots Picture of the Month, Feb 2007 and subsequently it was chosen as Sky at Night Magazine Hotshot of the Year, 2007. (Sky at Night Magazine). As part of the Sky at Night Hotshots competition, I won a 5x Astro Engineering barlow lens for the photo of the month, and a DMK41AF02.AS camera from The Imaging Source.

I’m very happy with this one – if anything, it needs a bit more data – especially in the colour channels – I’m tempted to have another go at this, maybe as a mosaic at a later date