Andrew’s Astronomy Blog

The constellation of Orion is home to many fine deep sky objects as well as M42 which featured in my last post. This one is IC-434, the Horsehead nebula. Probably the most photographed object in the sky it lies in the vicinity of the left star (Alnitak) in Orion’s belt (for northern hemisphere observers).

On the left hand side of the picture is the Flame nebula.

This is a work in progress and is a stack of the first four 5 minute exposures taken with GRAS-010, a  TEC 140 and SBIG STL-11000M camera with a luminance filter.

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.

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.