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 I try to log my observing and related activities in a regular blog - sometimes there will be a delay but I usually catch up. An index of all my blogs is on the main menu at the top of the page with daily, weekly or monthly views. My Twitter feed is below. I am also interested in photograping wildlife when I can and there is a menu option above to look at some of my images. I try to keep the news feeds from relevant astronomical sources up to date and you will need to scroll down to find these.

The Celestron 14 is mounted on a Paramount ME that I have been using for about 10 years now - you can see that it is mounted on a tripod so is a portable set up. I still manage to transport it on my own and set it all up even though I have just turned 70! It will run for hours centering galaxies in the 12 minute field even when tripod mounted.


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« Day 98 Saturday 28th June 2014 Drift Alignment | Main | Day 96 Thursday 26th June 2014 »

Day 97 Friday 27th June 2014 - Camera Orientation.

I went through the process outlined yesterday with the Paramount but could not get the mount to slew accurately to objects on the Eastern side of the mount. When I checked the home position it was HA 3.5 and should have been approximately - but not exactly - 2h. That can be caused either by incorrect synchronisation or inaccurate time or location setting. The time and location checked so it must by that I synched incorrectly. Having reset the home position to default the problem I had with unequal purple/red areas on either side of the meridian in the sky has corrected itself. I need to make sure that polar alignment is correct so I am going to abandon the paramount approach and go back to Drift Alignment tonight. I aim to use the camera to check drift direction.

The key is that

1. If the OTA is on the West side of the mount NORTH is at the TOP in the images taken by the camera.

2. If the OTA is on the East side of the mount SOUTH is at the TOP in the images taken by the camera.

To simplify things I need to make sure that the camera is N-S aligned. This shows the setup. This image shows the OTA on the East side of the mount.

Note that:

1. the counterweight bar is horizontal on the West side of the mount.

2. The OTA is at right angles to the polar axis so is pointing at zero declination.

3. The "top" of the OTA (arrowed) is aligned with North.

4. The camera is "upside down" so that the bottom of the camera - where the cables are - is also aligned with North and the top of the OTA.

If the OTA is slewed to the other side of the mount with the counterweight bar to the East it looks like this.

So the camera has turned upside down so that North is now at the top (rounded) end of the camera whereas previously North was at the bottom end. On the screen of course this means that North has moved from bottom to top also. Here is another way of looking at it.