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Spiral Galaxy NGC 2841

  • eansbro
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16 years 11 months ago #61704 by eansbro
Replied by eansbro on topic Re: Spiral Galaxy NGC 2841
Mike, I’m delighted you want to use it for a background on your PC.

Mira Pro is a powerful scientific tool for carrying out professional astronomical research. It would be a very expensive tool just for processing images. If you are serious into astrophotography where you want to do scientific work then Mira is an option. You would nearly as well at a fraction of the price use AstroArt or Maxim DL for processing images and obtain the same results.

However, to give you some idea of its potential here follows:

For example if you are searching for a star with an exoplanet, you
shoot many images of a widefield, over the course of a night. Then you generate lightcurves for many of the stars in the field (let's say 200).

That way any star with a varying mag lightcurve can be a candidate for an exoplanet.

Mira Pro by itself, or with the MExtract Module, can do that. Here are the
options in some detail:

1. Detect all objects matching some set of criteria (such as peaking
above some brightness threshold, being "round enough" to reject fuzzy
little elongated galaxies, being large enough not to be cosmic ray
hits or hot pixels, and, perhaps throw away the objects too close
together).
2. Match the objects detected in the image set which are found in all
of the images.
3. Do aperture photometry on the matched objects.
4. For the final step, check the "Detect Variability option and specify
a magnitude threshold. This will compare the photometry of each
matched object to the threshold and report those objects that are
found to vary through the image set.

Save the pipeline as a profile, like "Detect Novae" or something. Then
you can use it now or at some other time on a different set of images
simply using a click to execute your "recipe".

As a converse, you might change step 2 in the pipeline from "Match
Sources" to "Difference Sources". This will report objects that
are *not* found near the same locations in all the images. In other
words, it finds transients: things that brighten up suddenly to be detected in only some images or objects that are moving, such as minor planets.

Mark,

The biggest one technically speaking is at Birr.



Dave,

This all depends as you know on sky transparency. I usually carry out observed magnitude tests (OMTs) before I start out on a routine survey work. This involves a sequence of exposures in ascending order 30 secs, 75 secs, 180 secs, 475 secs. If I reach 21 mag in 75 secs I know the sky transparency is good. On occasions I have reached around 22.3 with a 240 sec exposure. I have never gone into exposures of hours.
As a senario, and assuming the above good sky transparency is steady for some hours then it would be possible to reach 25 magnitude.

If you now apply this exposure to a target that ideally is near zenith which NGC 2841 could nearly achieve at a specific time of the year then the results may show the following: It would first of all expand the galaxy disc to at least fifty per cent more than the present image. Show more in depth detail in the central area. Resolve more isolated stars in the vicinity.. To push the limits of this magnitude threshold you would have to leave out the filters. The filters will reduce the mag. threshold.

Eamonn A

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16 years 11 months ago #61706 by michaeloconnell
Replied by michaeloconnell on topic Re: Spiral Galaxy NGC 2841
Incredible detail there Eamonn! :shock:

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16 years 11 months ago #61718 by Gary Clarke
Replied by Gary Clarke on topic Re: Spiral Galaxy NGC 2841
Wow!!!! :shock: :shock: :shock:


One of the best shots I seen Eamon, the detail is incredible. You have just raised the bar again.

Regards,

Gary.
Clonee Observatory D.15.

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16 years 11 months ago #61720 by dave_lillis
Replied by dave_lillis on topic Re: Spiral Galaxy NGC 2841
The sheer image scale and detail make this one fantastic image, you've created a new imaging league of your own !

Dave L. on facebook , See my images in flickr
Chairman. Shannonside Astronomy Club (Limerick)

Carrying around my 20" obsession is going to kill me,
but what a way to go. :)
+ 12"LX200, MK67, Meade2045, 4"refractor

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  • eansbro
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16 years 11 months ago #61733 by eansbro
Replied by eansbro on topic Re: Spiral Galaxy NGC 2841
Glad you all liked the image lads. In the course of imaging the other night I managed to image other galaxies of interest. I am still post processing them. Last night was even bit better in sky transparency. I took some further images in the early hours of the morning.

Keith,

The BVR filters are broadband photometric filters. Used for enhancing specific details of interest within an image. They don't provide true colour when combined.

B filter is blue. Filters light between 400nm – 500nm, peaking at 440nm
V filter is visible. Filters light between 500nm – 700nm, peaking at 550nm
R filter is red. Filters light between 550nm – 800nm, peaking at 630nm

The above filters would be different to the common RGB filters ie. red, green, blue.

RGB filters are not photometric. RGB filters are very popular for CCD imaging to provide nearly true colour in an imaging.

Eamonn A

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16 years 11 months ago #61735 by Mike
Replied by Mike on topic Re: Spiral Galaxy NGC 2841
Hi Eamonn
Many thanks for your reply and of course experienced advice. Yes I suppose in my case I better learn to walk before I can run. I did download a thirty day trial version of Maxim DL during last summer, but as we all know here on the forum it rained for most of the summer and hence I did not get a good run to realise the full benefit and capability of this renowned program in a practical manner, therefore it is on my “must purchase” list! Glad to see that you have started a new website, looks good, keep those images coming!

Clear skies
Mike

I83 Cherryvalley Observatory

After one look at this planet any visitor from outer space would say; "I WANT TO SEE THE MANAGER".

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