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Enchilada
31-12-2008, 11:39 PM
H.N.Y. 2009!
I do have just a general query about the imagers here and what software (if any) they do any measurements with.
Writing lots general observational text about double stars and planetary nebulae - is certainly now much easier in determining placement of these objects for visual observers via planetarium-like software or from net imargery. The aim of course is to just help observers identifying fields and the location for iffy deep-sky on the very limits or threshold of visibility.
I admit I find it sometimes very difficult to match what I see in the wonderful images generated by astroimagers against the visual appearance. The main issue for me is how big some nebulae and galaxies are compared to the visual size seen in the 'scope. Next fm is the brightness / surface brightness of objects, against the visual limits or deep-sky boundaries.
Personally, I have begun to use wide field images from various sources using the Centre de Données astronomiques de Strasbourg (CDS) JAVA software, ALADIN Version 5.9.
Does anyone else also use this software (or others) with their own produced images - like what if often shown here in this thread? What sort of things do you actually gather from your images other than the necessary stacking, colour balance and visual processing?

Enchilada
01-01-2009, 11:20 AM
I should have given ALADIN's web address;

http://aladin.u-strasbg.fr/aladin.gml

or download it at;

http://aladin.u-strasbg.fr/java/nph-aladin.pl?frame=downloading

renormalised
01-01-2009, 12:19 PM
You won't match the objects you see in your eyepiece with what you see in astrophotos. Simple reason being your eyes aren't as light sensitive as the CCD in the camera that took the piccie, plus the image scale is entirely different. All you'll see in an eyepiece is a very dim and under-resolved version of the objects in the piccies. Plus you'll only see a dull grey-green or colourless view of the objects. There's no comparison. Your eyes, in most cases, won't see for the full angular size of any of the objects (much of the time neither will the camera, but it'll see a lot more than you will) because they become too dim on their outskirts or they're oriented unfavourably, etc.

I use ALADIN, sometimes just to play a round with, but mostly in a professional and academic capacity for when I need to study a particular object.

If I have to, I can measure angular size by eye, from the ALADIN pics, or if I'm having a bit of trouble I just enable the co-ordinate grid. Or, if I'm using a program like Photoshop, I use the image rulers to bracket an object and knowing the FoV of the original pic, I just do a few quick calculations to derive an image scale. Some of the more expensive image processing and analysis programs, such as MIRA and Maxim DL CCD, have applets that allow you to directly measure angular sizes of objects, etc.