Andrew's Astronomy Blog – Page 20 – Space: There's a lot of it out there!

M42 – The Orion Nebula

Global Rent A Scope run a free trial introduction on one of their Australian telescopes. One click imaging; all you have to do is select what you want to image from the list of visible objects and the system will select an exposure, convert the camera picture to jpeg and email it to you when it’s finished. The result from a single 2 minute exposure of M42 is pretty good on it’s own, but the system also files a copy of the original FITS image on the FTP server. This extends the possibility of stacking multiple images for a lower noise picture.

So, after taking 3 images in a row I downloaded them and opened them in Maxim DL. What was immediately clear was just how good a job the system does in automating the jpeg image production. It took me several hours work to get close to the system’s image. Here’s the finished result, the telescope is a Takahashi Sky-90 with an SBIG ST-2000 XMC camera.

Deep Sky Galaxy

The Triangulum Galaxy

Most of the GRAS telescopes have monochrome cameras so I haven’t done much with the one shot colour cameras. However, when I was looking for a telescope / camera combination for imaging M33 I realised that GRAS-003 (a Takahashi TOA-150 with an FLI 8300) fitted the bill exactly with the galaxy filling the frame.

Five 10 minute exposures later and this is the result:

M33 has a very low surface brightness due to the fact that it’s light is spread out over a large area. This makes it a difficult visual target but it responds well to long exposure photography.

While visible to the naked eye (given a low enough level of light pollution) no pre-telescope notes are made of it; you’d be unlikely to notice it unless you already knew it was there. It was catalogued by Messier in 1764 and was one of the first ‘Spiral nebulae’ observed by Lord Rosse.

At a distance of 2.8 million light years it is 50,000 light years across and contains around 30 – 40 billion stars.

Deep Sky Nebula

M27 – The Dumbell Nebula

Tuesday night was pretty clear so after taking the pictures of Albireo on the club’s 20″ reflector I switched to M27. The 20? has some problems with tracking and field rotation as it’s on a motorised Dobsonian mount so it’s best to use a high ISO setting on the camera and keep the exposures as short as possible. I took 30x 20 second exposures at ISO 1600 and 15 were usable although there’s some elongation visible in the final image.

M27 is a planetary nebula, recorded by Messier in July 1764. It lies about 1000 light years away in the constellation Vulpecula.

Deep Sky

Coloured stars

Ask any person in the street what colour stars are and you will usually get the answer; White. However, a closer study with the naked eye will reveal some differences in colour and with binoculars or a small telescope this is more apparent. Some double stars show a marked colour difference between the pair and this is apparent in this example, Albireo, the star marking the head of the swan in the constellation Cygnus.

Deep Sky Galaxy

NGC 247

Once you get past the members of the Local Group, the next nearest galaxies are in the Sculptor cluster. Back in November last year I posted an image of NGC 253 and this time it’s the turn of NGC 247 in the constellation of Cetus.

At a distance of about 12 million light years this is a rather distorted spiral galaxy, with a prominent star at one end and a sparce void at the other. Being relatively close, the galaxies in this group appear quite large, this one is about 2/3 of the diameter of the full moon in length but is too faint to be visible to the naked eye. The small galaxy in the lower right of the image is PGC002795 (ESO540-026).

This is a picture taken with GRAS-006 in Australia and consists of 3 five minute exposures. GRAS-006 is an RCOS 16? – FL 3654mm @ f/9.0 with an SBIG STL-1001E NABG camera.

Solar System

Jupiter & Io

With Jupiter so prominent in the evening sky it’s hard to take pictures of anything else. Saturday night was clear and I stayed out to image the moon Io crossing in front of the planet. Unfortunately, a fundamental error meant I inadvertently left the f/6.3 field flattener on the telescope and didn’t notice until I’d packed up at 12:30 and this has spoiled what otherwise may have been reasonable images.

Best of the lot is this one, an RGB composite of about 700 frames of each colour.

Solar System

Jupiter again

My first opportunity to photograph a moon shadow on Jupiter occurred on Tuesday evening as Calisto moved out from the planet just after dusk. The ’seeing’ was pretty bad so I used the 9.25″ Celestron without the x2 barlow and used the IR filter again. This f/10 combination enabled me to keep the individual exposures fairly short with a 10 fps framerate (the IR filter doesn’t let a great deal of light through!).

The final image is a stack of about 1500 frames (from an original video of 2300 frames). The Great Red Spot is also visible just to the right of the shadow.

Solar System

Jupiter

Post author By admin
Post date August 10, 2009
No Comments on Jupiter

Friday night was forecast to clear before midnight so I made the trip over to the observatory to setup the Celestron 9.25″. Right on cue, the clouds cleared (first time that’s happened in a long time) and I got quite a few 3 & 4 minute videos with the webcam and a narrow band IR filter (742nm). This is the result from the last video of the evening at about midnight, 800 frames stacked in Registax 5 with some additional processing in GIMP.

This image shows more detail than I’ve captured before and I put this down to the better than average seeing and a slight tweak to the telescope collimation. Jupiter is very close to opposition and has an apparent diameter of almost 50 arc seconds at the moment. The Great Red Spot is just creeping into view just below the equator on the left hand side.

Deep Sky Galaxy

The Pavo Triple

Many people are familiar with the Leo Triplet of galaxies, M65, M66 and NGC 3628. In the Southern skies there’s a similar formation in the constellation Pavo of NGCs 6769, 6970 & 6971 at a distance of 190 million light years. All three galaxies are interacting and whilst the cores consist of elderly reddish stars the spiral arms are lit up with clumps of new stars formed by the gravitation interactions.

Many other members of the Pavo galaxy group are also visible in this picture.

This image was obtained with GRAS-008 and is a composite of 10x 5 minute exposures. The image has ben scaled down by a factor of 3 for display on this blog.

Deep Sky Nebula

M57 – The Ring Nebula

I’ve imaged this object before using the Canon 350D in some very early experiments with imaging the night sky. This is the result of narrow band imaging using Ha, OIII & SII filters (3 ten minute exposures of each) with all three summed to produce a luminance frame. The telescope used was GRAS-2.

These images were taken with the moon in the sky as telescope time is much cheaper when this is the case and narrow band images are much less sensitive to the light from the moon.

This image is in false colour with Ha depicted in green, OIII in blue and SII in red. What is clear is that there is very little emission at the SII wavelength as there is very little red colour in the nebula. There is a central star in the nebula however, as it doesn’t emit light at the wavelengths used in this image it doesn’t appear in the picture.

OIII is an oxygen molecule in an ionised state that can only exist in very rarified gas clouds. It was first noticed during spectroscopic analysis of emission nebulae in the mid 19th century and mis-identified as a new element called Nebulium. It wasn’t until the 1920s that physicists correctly deduced it’s true form.