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Astronomy with an online telescope

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Picture of Robert Charlesworth

Robert Charlesworth Post 1

14 Jan 2021, 19:07

Telescope site object catalogue / telescope pointing

Where does get the celestial coordinates in its catalogue from?

I made several attempts to image M67, using the coords from the site's catalogue, and they were all out of frame (although not identically). I tried entering the coords from the object as displayed in Stellarium, both the J2000 ones and corrected for the day on which I submitted the job, but the cluster still wasn't all visible in the frame. Is there anything else I can try?


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Alan Cayless Post 2 (unread) in reply to 1

15 Jan 2021, 09:24

Hi Robert;

Thanks for trying M67 again. has its own internal catalogue, but the Stellarium J2000 coordinates should also work. 

If you can let me know the serial number (six-digit number beginning with "J") of one of your images, I'll check it out.


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Alan Cayless Post 3 (unread) in reply to 1

23 Jan 2021, 16:05 Edited by the author on 23 Jan 2021, 16:05

Hi Robert;

To help figure out what's happened I've requested some images of M67 myself and they have just come back.

In my images, the main part of M67 is also just off the left hand side of the frame.

It appears that the coordinates when selecting M67 by name are slightly out.

Try entering the co-ordinates manually, and enter:

Right Ascension    8h 51m 24
Declination     +11° 49' 0"

This should centre it up in the frame.


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Robert Charlesworth Post 4 (unread) in reply to 3

26 Jan 2021, 01:41 Edited by the author on 26 Jan 2021, 01:52

Hi Alan,

Thanks for chasing this up. Sorry I wasn't able to reply with my Job IDs earlier. I have submitted a new job with the coordinates you recommended. 

In my images the cluster was always off the right hand side of the screen. I'll include the jobs here for completeness:
J367440, J367981, J368338, J368580, J369706.
I settled on 120s for the exposure time, but even so not all of them came out. Does the telescope sometimes have trouble focussing? What could be the cause of this? I noticed a very blurred image when I tried to image the Sirus cluster, M41 (J369705)

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Robert Charlesworth Post 5 (unread) in reply to 3

26 Jan 2021, 01:51

Another quick question about telescope jobs:

When I submitted jobs with celestial (RA/DEC) coordinates I was often (not always!) able to enter an object name in the box below. Are these objects available to others using the site, or just me? I don't want to "pollute" the list of objects in the catalogue with tests of my own!
The name I gave to my second set of attempts was "M67 (stellarium 02/12/2020)". Does that appear when you search the object list?

Picture of Alan Cayless

Alan Cayless Post 6 (unread) in reply to 5

27 Jan 2021, 16:09

Hi Robert;

Thanks for thinking of this - it's OK: the name you choose will only appear on your list !

And you asked about focusing - the telescope can sometimes return out of focus images.  It may be partly due to temperature changes.  We will upgrade the focuser at some point to fix this, although it's not so easy at the moment with travel restrictions.


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Robert Charlesworth Post 7 (unread) in reply to 6

30 Jan 2021, 22:06 Edited by the author on 30 Jan 2021, 22:08

Hi Alan,

The image of M67 from the coords you gave me has now come back - and unfortunately it looks like this:

The background is red, rather than black. Do you know what has happened here? Is it a problem with the dark frame? I can edit it slightly using the controls on the website, but can't remove the coloured background without losing the stars. Is there any way of doing this using other software?


Picture of Alan Cayless

Alan Cayless Post 8 (unread) in reply to 7

1 Feb 2021, 13:53 Edited by the author on 1 Feb 2021, 13:54

Hi Robert;

Thanks for having another go - and it's good to see that those coordinates have worked, and the cluster is now centred !

The red background is the result of the colour balance between the filters.  The telescope takes three separate images through Red, Green and Blue filters to make up the colour image and these don't always get matched up exactly by the default settings in the View window.   

Fortunately, the colour balance can be corrected on the Edit tab.  There's an adjustment icon with three vertical bars (red, green, blue).  If you select this and then "Auto" it will match up the exposures of the three frames and that will get rid of the red background.



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