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NGC3344 - The Sliced Onion

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#1 aacc66

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Posted 18 February 2019 - 12:57 AM

NGC3344 is medium sized spiral galaxy, 20 million light years away.  It seems to be a lonely galaxy but its motions seems to make part of the Virgo super cluster.  The galaxy  has an apparent magnitude of 10.5

 

here are the settings:

- Edge HD 9.25 on CGEM
- UnMod Sony a7s
- Light Subs (15 hours 42 minutes 0 sec) 1,884 x 30 sec Subs. Data from 5 Nights
- ISO 6400
- Calibration with dark, flat and bias images
- Registering & stacking with DSS 4.10 64Bits
- Post-processing in PI with pseudo luminance channel.
- Red Zone

 

Note: I did try to reduce the size of the stars, but the galaxy has 2 large ones right in front of it, so I left the reduction to another opportunity.

 

C&C welcome.

 

Alvaro

 

PS: I notice that placed the wrong picture, where there is no color in the stars.  Hopefully this one is better.

 

NGC3344_15h42m0s_Cr_2DBE_NL_LRGB_LHF_colorSaturated_v1_Small.jpg

 

 


Edited by aacc66, 18 February 2019 - 01:13 AM.

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#2 skycamper

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Posted 18 February 2019 - 01:54 AM

Pretty awesome photo, 5 nights wow!  what is your method of flats and how many from each session?  Great photo!


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#3 44maurer

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Posted 18 February 2019 - 02:00 AM

1st nice image
2nd this is the second post where someone had 1800 exposures, that’s crazy. Why not take longer exposures?

#4 aacc66

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Posted 18 February 2019 - 08:31 AM

Pretty awesome photo, 5 nights wow!  what is your method of flats and how many from each session?  Great photo!

For each session, I will take about 50 flats for pre-meridian and 50 for post-meridian, but those are quick.  btw: I have a light box that help me take the flats.  I'll take 30 darks for the night session and depending on the the temperature differences between the nights , I will share 100 bias.   Still too noisy for my taste.

 

Alvaro



#5 aacc66

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Posted 18 February 2019 - 08:41 AM

Thanks, the main reason for so many exposures is that I am using a Sony a7s and there (well maybe one out there) not code to use it in bulb mode when using the shutter.  Lately I am having to use silent shutter and with that you loose the bulb option.  And I am in a red zone, moving quickly to white zone as the city is starting to use LED lighting, so short exposures and high ISOs seems to work.  Also I have an F/10 system, so I need a lot of hours to fight the noise, and barely can do it.   It is not optimal and I think my mount can handle the long exposures.

 

Alvaro

1st nice image
2nd this is the second post where someone had 1800 exposures, that’s crazy. Why not take longer exposures?



#6 44maurer

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Posted 18 February 2019 - 10:55 AM

Thanks, the main reason for so many exposures is that I am using a Sony a7s and there (well maybe one out there) not code to use it in bulb mode when using the shutter.  Lately I am having to use silent shutter and with that you loose the bulb option.  And I am in a red zone, moving quickly to white zone as the city is starting to use LED lighting, so short exposures and high ISOs seems to work.  Also I have an F/10 system, so I need a lot of hours to fight the noise, and barely can do it.   It is not optimal and I think my mount can handle the long exposures.
 
Alvaro


Thanks for the info, I’m in a Class 8 Bortle, SQM 18.5, can’t emphasize enough the importance of a good light pollution filter.

#7 aacc66

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Posted 19 February 2019 - 12:37 AM

Thanks for the info, I’m in a Class 8 Bortle, SQM 18.5, can’t emphasize enough the importance of a good light pollution filter.

I do have to point out right now my camera is not working well using normal shutter (age, and outside temperature, and lack of descent software for bulb functionality) and I am limited to silent shutter which doesn't allow bulb mode.

 

I do have a question about LPFs.  My understanding is that LPFs take advantage of early types of city illumination, e.g. low pressure sodium lamps emitting ~695nm.   This is typical of city street light and LPFs are tailored to reject that spectrum.  But now, and that is the case in my street, the city has switched to broadband LEDs, and I believe LPFs will not work as well to reject that light pollution given that it is broadband.  Am I missing something here?

 

Alvaro



#8 skycamper

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Posted 19 February 2019 - 11:32 PM

I do have to point out right now my camera is not working well using normal shutter (age, and outside temperature, and lack of descent software for bulb functionality) and I am limited to silent shutter which doesn't allow bulb mode.

 

I do have a question about LPFs.  My understanding is that LPFs take advantage of early types of city illumination, e.g. low pressure sodium lamps emitting ~695nm.   This is typical of city street light and LPFs are tailored to reject that spectrum.  But now, and that is the case in my street, the city has switched to broadband LEDs, and I believe LPFs will not work as well to reject that light pollution given that it is broadband.  Am I missing something here?

 

Alvaro

Thats exactly how I understand it. Yes.



#9 aacc66

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Posted 19 February 2019 - 11:43 PM

Thank you for all the likes. 

 

I do have a puzzle.  I annotated the image and there is an object that seems to look like a galaxy, but the image analysis and annotation seems to not have any information on it.  I even went to Simbad and it doesn't identify it; but I was able to use Simbad to get the Ra and Dec for it, which is : 10 43 0.878 +24 40 55.36

 

I assume that I am doing something wrong with image analysis and the annotation and maybe someone can point me to the correct library for this object.  I would like to know the id name for it.

 

Thanks,

 

Alvaro

 

The image should show the object with a yellow arrow with respect to NGC3344 and there is also the annotated version showing that it is not marked. And a larger picture of the object inside the yellow dashed box.

 

NGC3344_Unidentified_Object.jpg

 




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