Ballard Loc: Grass Valley, California

I recently reprocessed an image I took of the Pleaides star cluster and notices a few small galaxies where also caught in the image. The image below shows 3 of those galaxies highlighted in an greatly enlarged boxes. The galaxy in the upper portion of the picture is PGC 13696 (also called UGC02838) and has a magnitude of 17.29 (very dim). Below the Pleaides is PGC 13992 (also called UGC02880) and has a magnitude of 16.95 (also very dim). The third galaxy didn't show up in my charts and I labeled it unknown. (I need to check online as I'm sure there is a catalogue that will contain it).
There are a number of other dim fuzzy objects I found in the image that are also probably distant galaxies. When I get a chance I will try some longer exposures are higher magnifications to confirm that some of these faint fuzzy objects are indeed galaxies. In general wherever you look in the sky there will be galaxies, just many are very faint or obscured by dust and stars in the milky way.

PGC = Principle Galaxy Catalogue
UGC = Uppsala General Catalogue (Named for the oldest astronomical observatory in Sweden in the town of Uppsala)

The Pleaides (also known as Messier object 45) is a very young open star cluster (>100 million years old) where the nebula that formed the stars is still very visible (Note faint traces of the nebula extend throughout the image). The Pleaides is fairly close astronomically speaking at only 136 years distance.

All comments, suggestions and questions are welcome.

Pleaides Star cluster

(Download)

dave.m

always interested in star photography - tried it more than once with only a little success.

Can you give us camera/ lens / exposure details and how you post processed so we can learn from you?

Ballard Loc: Grass Valley, California

Hi Dave
This is a stack of 20 images, each 3 minutes long. The images (called light frames) were taken with a full frame canon DSLR with the ISO set to 1600 and using 500mm F4.0 canon lens. The lens and camera where piggy backed on a 5 inch Apochromatic refractor that was used for guiding the camera. To guide the setup a Starlight Express lodestar X2 ccd was inserted in the refractor and connected to a laptop computer via USB connection. The computer was also connected to a Losmandy Gemini 2 controller via ethernet. The Gemini 2 controller controlled DC servos on a 25 year old Losmandy G11 mount that I had upgraded with the Gemini 2 controller and DC servos a few of years ago. The computer was running the freeware telescope guiding PHD software that talks to the Gemini 2 controller via the freeware ASCOM platform used for telescope control. With the PHD software you can see star images in real time from the CCD on the computer screen, pick (click on) a reasonable star and PHD software will control the mount to keep the star stationary in field. Note: although the mount will run by itself at sidereal rate, there are always imperfections due to the mechanics and the atmosphere that cause errors without active guiding. I controlled the DLSR via the canon EOS software the comes with the DSLR camera. The camera was also connected to the laptop via a USB connection. Since I'm also a bit of a wuss when it comes to cold weather, once I got the camera in focus I would remote the windows laptop interface and control everything from my windows 10 desktop from inside my office.
For stacking and processing the images I use to use the freeware program deep sky stacker but I splurged and purchased a pixinsight that has a lot more processing control for deep sky images and that is what I reprocessed this image of the Pleaides with. To remove much of the thermal noise from the camera sensor I used ~20 dark frames. Dark frames are images taken with the lens cap on for that same amount of time, with the same ISO setting and ~ the same temperature as the light frames. The dark frames are used by the stacking software to remove thermal noise in the sensor. I also used bias frames to remove any electrical noise from the frames. Bias frames are very short exposure frames are taken with the lens cap on at the same ISO and temperature doesn't matter since these are very short exposures and used by the software to remove any inherent noise added by the read circuit in the camera. The other type of frames used where flat frames which are short exposures taken with the same optical train, ISO and F stop as the light images but with even illumination (typical a white shirt covering the lens and looking at the sky, also a good idea to rotate the shirt between exposures to average out any bias introduced by the shirt. The flat frames are used by the stacking software to remove any vignetting and dust specs that might be in the optical train. (you can look up dark, bias and flat frames on the internet to get details on how to create and use them). If you only do one I find that darks are the most important. If you have any other questions let me know.

Ballard Loc: Grass Valley, California

oops I said the Pleiades was ~136 light years away that should have been 136 parsecs away (~442 light years), still close astronomically speaking. I also swapped the a and i in the Pleiades in the above discussion (my fingers sometimes have dyslexia).

Longshadow Loc: Audubon, PA, United States

dave.m

Wow! it is temping to be flippant and ask if I can get the bits at Walmart, but seriously, thanks for such a detailed reply, parts of which I understood (multi- llong-exposure stacking, the need for a top end tracking device for such very long cumulative exposures, and suitable stacking software.)

I'm in the process of building Gary Seronik’s analog barn door tracker which while in a much lower league I hope will give me a start in long star exposure with tele lens. Will read up more on the bias frames to remove noise.

Thanks again Ballard

Ballard Loc: Grass Valley, California

Hi Dave
That kind of tracker will work fine for 30 to 60 seconds with a 50mm lens with good polar alignment. I built one of these years ago to get some shots of Comet Hale-Bopp in the late 90's when I was using film. Now with digital you can still use the dark, bias and flat frames to help those wider angle images. The freeware deep sky stacker program can be used as a good way to start.
One step up would be with a camera tracker like Sky-Watcher Star Adventurer (there are many brands of products that do this) that can allow several minute exposures with 200mm lens and are easy to polar align. It is a fun hobby and can get expensive as you get more and more into it.

Hal81 Loc: Bucks County, Pa.

You cant fool me. Their UFOs watching our every move. Im hiding under the bed.