And I Though There Had Been Changes Up Until Now! (And, I finally found a way to start publishing again! This is what should have been published in February.)
Since the last entry on March 1, 2023, there have been more changes than I would have ever imagined. For one, we no longer live in Georgia. Another would be we now live in a house, not a CCRC. The plus side on this is that we are now in the same area as our daughter, and family, including grandkids. Our son, and family, is planning a move to this same area within 2025. Needless to say, being around family is a HUGH plus.
On the down side, I have the most limited view of the sky I think I have ever had. Astronomy is done within a radius of about 20 degrees of a point about ½ way between the horizon and the North Star. As such, the sun, moon, and planets are all out of sight (in the trees, actually, and not MY trees at that, so I can't cut them down, not that I would anyway). I am in a Boortle 7 zone, so light pollution is a major factor. However, I stumbled on a technique that seems to work, mostly. However it's useful primarily for stars and/or star clusters. All of this comes thanks to the processing power of the program Siril. See https://siril.org/ .
So, it goes like this. On the night of January 27th, I decided to try imaging the open star cluster NGC957 in the constellation of Perseus. It's Mag 7.6 and about 11 arc-min in size. The scope that was set up was the Stellarvue 102T with the (aging) QSI683 camera, so... off to the races.
What follows starts with the original image:
NGC957 as supplied from camera
This is 10 minutes of exposure in each of the LRGB bands; so a total of 40 minutes of exposure. This is a pretty common to not be able to see what you have imaged until “stretching” of the image is done. Stretching is basically remapping pixel values of a lower value to a higher one. After stretching, the image looks like this:
NGC957
Master LRGB Siril Stretched Gimp scaled
This is as good as I can usually get my images, and this isn't too terribly bad. However, I tried something a little different, mainly to see if I could “see” how much light pollution is in the images.
So, starting with this image, I went back into Siril and used the subroutine Starnet+, which tries to remove the stars from your image. Actually, what you end up with is 2 images; one is just the stars and the other is what is left over, in this case the background illumination. I'm assuming that “background illumination” equals my light pollution. Here are the 2 images:
starmask_Master LRGB Siril Stretched
This is just the stars. If you look VERY closely, you can see that the background between the stars is almost black, not a mottled gray. You might also note that some vertical “banding” to the left of the cluster now appears to be gone. The vertical banding is a (now) known defect in the camera. Fortunately, it doesn't affect all QSI683 camera. Unfortunately, it affects mine.
Below is the “background” or what I'm calling the “light pollution” image.
starless_Master LRGB Siril Stretched scaled.
Now you should be able to see 1) the amount of light pollution the image was taken in, and 2 the vertical banding on the left side of the image. Just for fun, I inserted a “reference black” circle in the upper right corner. This reference is NOT ACTUALLY BLACK, but is about the color of the sky (exclusive of stars, nebulae, etc, of course) of a dark sky site. This sky color used to be the norm, but we, meaning all of us, ie mankind, have “turned on the lights”. This is the result. I think I read somewhere where my children are the first generation in the history of mankind to NOT experience a dark night sky. This is something that has been studied for nocturnal animals, etc. and the results are not good. It is also being studied for humans. The preliminary results are just starting to come in, and it appears that not having a dark sky does have some effect on humans. Much more work needs to be done, but we are venturing into unexplored waters, so to speak.
