Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Where are my galaxies

  • Please log in to reply
14 replies to this topic

#1 Remaxman

Remaxman

    Vostok 1

  • -----
  • topic starter
  • Posts: 135
  • Joined: 16 Jul 2017
  • Loc: Pickering Ontario

Posted 26 May 2019 - 11:14 PM

3rd night out. Taking photos all around the handle of the big dipper. there are galaxies there. But I can seem to find them. All my photos look like the one i posted. What am I doing wrong? This photo was with a Nikon d5300 50mm lens 120sec x 10 stacked in DSS. This was just so I could see just a hint of a galaxy. Nothing. I have done a dozen sets of photos all over that area and nothing. Im using Star Adventurer for tracking as well. Any help would be greatly appreciated. 

 

 

Attached Thumbnails

  • stars Sunday-2.jpg


#2 fmeschia

fmeschia

    Viking 1

  • *****
  • Posts: 964
  • Joined: 20 May 2016
  • Loc: Mountain View, CA

Posted 26 May 2019 - 11:43 PM

If you upload the image to nova.astrometry.net, it will plate-solve it and show you what you imaged. In this case, here’s what you’d get:

 

3399471.jpeg

 

There are a few galaxies in your field, but with this image scale, and because of the focusing which is not perfect, they’re hard to spot. One of them is M101, visible as a fuzzy patch slightly to the right of 86 UMa.

 

Francesco


  • psandelle, james7ca, happylimpet and 4 others like this

#3 james7ca

james7ca

    Fly Me to the Moon

  • *****
  • Posts: 6843
  • Joined: 21 May 2011
  • Loc: San Diego, CA

Posted 26 May 2019 - 11:52 PM

There are only a few galaxies around the Big Dipper that are going to be obvious in an image taken with a 50mm lens and at the small scale of the image you've posted I can't really tell where you had the camera pointed.

 

Actually, I took a copy of your image and ran a blind solve on Astrometry.net and it came up with the following solution:

 

Center (RA, Dec): (229.120, 52.359)
Center (RA, hms): 15h 16m 28.918s
Center (Dec, dms): +52° 21' 30.903"
Size: 26 x 17.3 deg
Radius: 15.618 deg
Pixel scale: 156 arcsec/pixel
Orientation: Up is 167 degrees E of N

 

I've also attached the labeled image that was created by Astrometry.net and it appears that you really weren't pointed toward any galaxies in the Big Dipper. Sometimes it can be hard to tell exactly where the camera is pointed when using a simple star tracker.

 

It looks like the galaxy NGC 5866 (the so-called "Spindle Galaxy") which has been identified as the "missing" M102 was just about in the center of your image. But that is a 10th magnitude object that is only 2.8 arc minutes in width (very thin, edge-on spiral galaxy).

 

Here is a link where I imaged the galaxy M51 using a 105mm lens, so with a 50mm the galaxy would be even harder to see.

 

  https://www.cloudyni...dpost&p=8573328

Attached Thumbnails

  • Image Solve.jpg

Edited by james7ca, 26 May 2019 - 11:58 PM.

  • raidambrosio likes this

#4 james7ca

james7ca

    Fly Me to the Moon

  • *****
  • Posts: 6843
  • Joined: 21 May 2011
  • Loc: San Diego, CA

Posted 27 May 2019 - 12:37 AM

Yes, as Francesco noted M101 would appear just inside of 86UMa (I missed that when I looked at the solve from Astrometry.net). Also, note that M101 is the largest galaxy in the Big Dipper, although I suspect that M51 would be easier to record since it has a higher surface brightness.

 

Below I've identified M101 (I think, hard to be absolutely sure at this image scale).

Attached Thumbnails

  • Image Solve M101.jpg

Edited by james7ca, 27 May 2019 - 12:46 AM.

  • zakry3323 likes this

#5 sg6

sg6

    Fly Me to the Moon

  • *****
  • Posts: 5084
  • Joined: 14 Feb 2010
  • Loc: Norfolk, UK.

Posted 27 May 2019 - 02:21 AM

For a "field" of galaxies you would be better aiming at the rear end of Leo - however it is steadily disappearing.

 

You may not seem to have what you expected or hoped for but the image has come out well.

 

Even with the Leo galaxies (Virgo cluster) the galaxies are going tom be small and a 50mm lens is not going to make them big. I also recall one comment that the eye is selective and the camera is not. You will pick out a galaxy and exclude the rest, the camera just reproduces it all.



#6 james7ca

james7ca

    Fly Me to the Moon

  • *****
  • Posts: 6843
  • Joined: 21 May 2011
  • Loc: San Diego, CA

Posted 27 May 2019 - 02:51 AM

As per sg6, here is an image I did back in 2012 using a 105mm lens and a manually driven barn door tracker. This is centered on the so-called triplet galaxies in Leo. Below is the image and the documentation I created back in 2012 (explaining the image).

 

 

The Leo Triplet of Galaxies, Plus NGC 3596, NGC 3593, and NGC 3666

 

All six of these galaxies were captured in the same, wide-field image that was taken with a 105mm telephoto lens mounted to a Nikon digital camera. The base exposure time was only ten seconds, although multiple images were recorded and then combined ("stacked") to produce a higher-contrast and lower-noise result.

 

The circles that have been drawn over the center part of the main image identify the locations of the galaxies (the larger circle covers the three galaxies that make up the so-called Leo Triplet -- NGC 3628, M 65, and M 66). Along the right side of the picture are 100% scale inserts that were taken from the original capture (i.e. what you see along the right side are enlarged clips from the wide-field image that forms the larger background to this photo composition). These inserts are arranged just as you will find the galaxies in the main image when reading from top to bottom.

 

The most distant galaxy in this sequence is probably NGC 3666 (at the bottom of the photo, it is also the faintest at around magnitude 12). NGC 3666 may be almost 60 million light-years away while the Leo Triplet is usually reported to be as distant as 35 million light-years. NGC 3596 (at the top) is a face-on spiral galaxy that may be about 50 million light-years away and it's interesting to note that the enlarged insert actually seems to show a nearly perfect circular disk with a slightly brighter central core (this structure may just be an imaging artifact, but it does match some of the large scale photos I've found of this galaxy on the internet).

 

The field of view on the main image is slightly smaller than you would get with a 150mm lens on a full-frame 35mm camera (or 100mm on an APS-C format camera) except that the image has been cropped to make it square. In angular measure it covers about eight degrees on both the horizontal and vertical axes (fairly close to the field of view with a pair of 7x50 binoculars). The field of view on the enlarged inserts is about 15 arc minutes (1/4 degree, or about one half the size of the full moon). For example, you can see that the galaxy NGC 3628 nearly fills the full diameter of its insert which would indicate that its size is about 15 arc minutes (15'). Wil Tirion's "The Cambridge Star Atlas" lists the size of this galaxy as 14.8' x 3.6', so there seems to be agreement in the numbers.

 

Attached Thumbnails

  • Leo Triplet with 105mm Lens.jpg

Edited by james7ca, 27 May 2019 - 02:51 AM.

  • Traveler and psandelle like this

#7 Remaxman

Remaxman

    Vostok 1

  • -----
  • topic starter
  • Posts: 135
  • Joined: 16 Jul 2017
  • Loc: Pickering Ontario

Posted 27 May 2019 - 09:29 AM

Wooooo whoooo looks like I did get a galaxy lol. 

 

Ok lets take the M101. If I get very close polar alignment, and a 600mm lens, 100 60sec lights, 25 blacks, 25 bias and 25 flats. And I get very good focus and m101 Centred. Will I get a good photo? I can stack in DSS, remove LP in PS etc. The only reason I used a 50mm is to get a wide view. By the way I’m just east of Toronto but light pollution isn’t extremely bad here. 

 

Thanks everyone

 


Edited by Remaxman, 27 May 2019 - 09:35 AM.


#8 RedLionNJ

RedLionNJ

    Gemini

  • *****
  • Posts: 3384
  • Joined: 29 Dec 2009
  • Loc: Red Lion, NJ, USA

Posted 27 May 2019 - 10:04 AM

A 600mm lens is 12 times the focal length of a 50mm lens.  That means you'll need your tracking to be 12 times as good.

 

And if the 600mm is the same (astronomical) aperture as the 50mm, you'll be using a significantly slower optical system, too.  Need a ton more subs.

 

In your favor is the high declination of Ursa Major.

 

Good luck!



#9 Traveler

Traveler

    Mercury-Atlas

  • *****
  • Posts: 2916
  • Joined: 19 Aug 2007
  • Loc: The Netherlands

Posted 27 May 2019 - 10:38 AM

Try point your 50mm lens on Andromeda. Then you will see M31 and maybe M33 on your stack. Good luck!



#10 aa5te

aa5te

    Genial Procrastinator

  • *****
  • Posts: 1746
  • Joined: 30 Aug 2008
  • Loc: Clinton, TN

Posted 27 May 2019 - 10:42 AM

Here's one of my first attempts of the Pinwheel; 25 lights @ 45 sec.,ISO 1600, Orion 6" f/4 w/1.1x GSO coma corrector (equivalent to 671mm @ f/4.4), Sony A6300, Orion SkyView Pro mount, stacked in Starry Sky Stacker for Mac and adjustments in Luminar 3. So yours will be about 90% of this size due to the lack of a magnifying coma corrector (assuming that's how your setup is).

 

Download Stellarium; one of its features is that you can input your camera's sensor size and various focal length lens and then you can click thru all of the combinations once you center on an object to roughly see how it will appear and how much of your FOV it will occupy.

Attached Thumbnails

  • 53413527_2153095224744574_9047132576463978496_o.jpg

Edited by aa5te, 27 May 2019 - 10:42 AM.


#11 fmeschia

fmeschia

    Viking 1

  • *****
  • Posts: 964
  • Joined: 20 May 2016
  • Loc: Mountain View, CA

Posted 27 May 2019 - 11:45 AM

Wooooo whoooo looks like I did get a galaxy lol. 

 

Ok lets take the M101. If I get very close polar alignment, and a 600mm lens, 100 60sec lights, 25 blacks, 25 bias and 25 flats. And I get very good focus and m101 Centred. Will I get a good photo? I can stack in DSS, remove LP in PS etc. The only reason I used a 50mm is to get a wide view. By the way I’m just east of Toronto but light pollution isn’t extremely bad here. 

 

Thanks everyone

With 600 mm focal length, unless you have a premium mount, you’re likely to need to guide anyway. M101 is fairly large but has a low surface brightness.

 

For reference, here is an uncropped picture of M101 I took from a dark site (SQM 21.5 mag/arcsec2) with a 5” refractor at f/5.6, focal length 730 mm, on an APS-C DSLR (Nikon D5500). The total integration time was rather short (56 minutes, 7x8 min subs), so I had to be a bit aggressive with noise reduction, maybe too much.

 

Francesco

 

47457500012_170234a1e6_c_d.jpg



#12 Remaxman

Remaxman

    Vostok 1

  • -----
  • topic starter
  • Posts: 135
  • Joined: 16 Jul 2017
  • Loc: Pickering Ontario

Posted 27 May 2019 - 12:55 PM

Photos from my Meade 125EXT is out of the question. So I’m stuck with DSLR. Guiding is in my future. My ETX has a fantastic tripod which I think I’m going to start using with my Sky Star Adventurer. 



#13 OldManSky

OldManSky

    Apollo

  • *****
  • Posts: 1039
  • Joined: 03 Jan 2019
  • Loc: Valley Center, CA USA

Posted 28 May 2019 - 09:40 AM

Remaxman, let me give a terrestrial analogy:

 

Look at the image below.  Where are all the birds?

Well, there are almost certainly lots of them in there.  The image scale is just too small (too "zoomed out") to see them.

That's where you're at with a 50mm lens smile.gif

 

 

Attached Thumbnails

  • forest.jpg

  • Traveler likes this

#14 Remaxman

Remaxman

    Vostok 1

  • -----
  • topic starter
  • Posts: 135
  • Joined: 16 Jul 2017
  • Loc: Pickering Ontario

Posted 28 May 2019 - 10:07 AM

****!!! Thanks OldManSky


  • OldManSky likes this

#15 droe

droe

    Viking 1

  • *****
  • Posts: 802
  • Joined: 01 Jul 2015
  • Loc: Fenton, Mi

Posted 30 May 2019 - 10:03 AM

M51, the whirlpool galaxy is close-by and would be a good target. Easy to spot.

 

sml_gallery_245739_7234_103876.jpg




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics