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ART Staff Blog Feed

Ed

Master Dark and Bias Frames

posted by Ed on 5 August 2014

In order to get a good image back from a CCD on the back of a telescope, there are a number of processes you have to put the image through to account for discrepancies and errors. These include applying bias and dark frames as well as flat fielding. We handle these for you automatically, but for those that like to do things by hand we are now producing master dark and bias frames for more advanced users to use.
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Ed

A Guide to Filters

posted by Ed on 8 July 2014

There are a wide range of filters available on our cameras. Different cameras have different filters. These filters have strange names, which may be confusing if you've never seen them before. I dedicate this post to explaining what these filters are and when to use them.
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Ed

Object of the Month - The Milky Way

posted by Ed on 24 June 2014

Our telescope is pretty uniquely capable of capturing images of the milky way in all its splendour thanks to the wide field cameras you are able to request images from. The only difficulty is working out what to point at, as the milky way takes up quite a lot of the sky. (Or all of it you could argue).


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Dan

Maintenance Trip June 2014: Mount rebuild timelapse

posted by Dan on 11 June 2014

Each summer we re-grease the Ra and Dec drives on the mount as a part of our routine maintenance. This year we decided the make a timelapse video of the process to show everybody what we get up to on the maintenance trips.
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Chris

The Power of Ice

posted by Chris on 10 June 2014

There's always an odd problem to discover when we arrive on site at the observatory. This time it's a fairly minor one. See what the ice over the winter did to our Pole Star camera housing:




Dan points out that this is a high quality expensive camera housing too.

Ed

Object of the Month - Trifid Nebula

posted by Ed on 20 May 2014

There is a lot of gas and dust in space. Most of it we can't see because both the dust and the background of space are very dark. Generally speaking, there are three different reasons we might get to see this dust. The Trifid Nebula (Messier 20) is a great showcase for this as it demonstrates all three in a single object. This also makes it an interesting object to try and image.


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Dan

Telescope Operation

posted by Dan on 6 May 2014

Over the last fortnight the operation of the telescope has been somewhat disrupted. This reduction in the capacity of the service has been a result of two unconnected reasons.

Dome code development
The first of the reasons is development of new code to control the dome. Over the last six months we have have made various improvements to the code controlling the dome in an attempt to minimise its impact on images. The dome now attempts to track the mount as it moves in real time through the imaging process. We are hoping to add new code soon which will make the dome aware of the extent to which the dome is obscuring the imaging camera, this will allow the dome to make more intelligent decisions about when it is necessary to rotate to follow the camera.

The changes to the dome code have resulted in a large increase in the amount of communication with the dome, and also have changed the communication from happening in a single thread, to requests coming in from multiple threads. The existing dome control code is thread safe, however the increase in communication appears to now be overwhelming the dome controller; this problem has necessitated a change in the way in which we communicate with the dome. The alterations to the dome control code have required numerous changes throughout the system. Testing and refining of this code has required frequent restarts of the controlserver software. In some circumstances the restart of the controlserver software resets the cool count of the system to zero, this effectively takes the Galaxy camera off-line as it waits to cool again. Whilst this is frustrating, the system does continue to image on the Constellation and Cluster cameras, minimising the amount of lost observing time. I have talked with Chris and believe that we now have a way to indicate on the website when new code development is happening.

Mount pointing errors
We have recently started to have pointing errors with the mount. We are still working to understand the cause of these errors. The system is designed to reject images which have a pointing error in excess of certain predetermined values. Whilst we continue to work on this problem a larger than normal number of the images taken on Galaxy camera will be rejected and discarded by the system. These rejected images are shown in the RTD feed, but their imaging is not recorded in the list of work undertaken in the last night's jobs page; this often makes it looks like the system hasn't done much work in a night.

We have not reached the end of the dome code development cycle, or resolved the mount pointing errors yet. As we move forward with the work we hope to keep you all a bit better informed about what is going on.



Ed

Fun with Domes (PART 4)

posted by Ed on 24 April 2014

The dome pointing algorithm has so far been improved a good amount but there are still some things that can be done; things that require much more than merely tweaking some parameters.
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Ed

Fun with Domes (PART 3)

posted by Ed on 24 April 2014

This is where I start delving deeper into the mathematics behind the dome control algorithms. After all this it was a good week before I stopped having dreams about spherical polar coordinate transforms.
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Ed

Fun with Domes (PART 2)

posted by Ed on 23 April 2014

In my last blog post I talked about how I had started to investigate the positioning of the dome and I had found some areas of the sky where the galaxy camera was being obscured by the top of the dome.
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