Comment on posted image of Tulip Nebula, Sh2-101, HD 227018
New to this. You machine tracked and made one 90 minute exposure? No tracking and stacking? I don’t see any grid marks so not sure exactly top bottom left right limits of the region.
You used jpg (lossy format) rather than png or some other. But the peak intensity for RGB is about 15 out of 255. The averages are 49.99, 40.65, 41.93 for RGB.
The ZWO 2600 MCP uses the Sony IMX571 sensor which is capable of 16 bit per color plane. Readout mode 7 has 2080×1388@110 fps and 12 bits. Not sure of the maximum gain. I found one example using gain 100 at 16 bits, but most at 12 bits. Many exposures digitally is equivalent (with registration and tracking) to longer exposures, and you can pick “good” ones. Higher gain would saturate a long exposure, but gain 90 one minute is roughly equivalent to gain one 90 minutes. And the frames are human viewable.
The total intensity for the image is 368 million in cameras intensity units (0-255 per color). That, divided by 90*60, is 68,182 levels per second. But raise the gain and that can go up substantially.
I cannot see the sky, but I have been experimenting with high frame rates with ZWO and other cameras. Raise the gain and the frame rate together and it gets grainy, but the statistics don’t care too much, as long as it is registered. Why do people use night scope in war – amplification. And you seem to be using none, just waiting long times. Maybe I am wrong. I cannot tell from your brief description.
Hope you find this marginally interesting. I keep looking for lossless images. The NASA types are mostly lossy, or so beyond the means of everyday users a bit off-putting. And I want to watch for hours or days or years, and they give one snapshot and call it a night.
Richard K Collins, Houston Texas
I found this https://www.sony-semicon.co.jp/products/common/pdf/IMX571BQR_Flyer.pdf and translated a bit. It said:
36 dB = 10^3.6 = 3981 max amplification
6.84 max frames per second in still picture mode of 6280*4264 at 16 bits.
I have only been able to get useful results with x100 on the gain and x100 on the frame rate. Often much less It depends on the available light. Trying to find the spectral response of the sensor.
Here is a useful set of curves for common sensors at https://s1-dl.theimagingsource.com/api/2.5/packages/publications/whitepapers-cameras/wpspectsens/a5cb0f39-fea8-56ae-8e04-ec20ab4e72c9/wpspectsens_1.30.en_US.pdf
The ZWO specs give some things https://astronomy-imaging-camera.com/product/asi2600mc-pro-color
Richard K Collins
Still trying to get a sense of the scale, and to understand what, in the picture you are calling “tulip” I found this:
Tulip Nebula, Sh2-101, apparent scale in the sky
https://astroanarchy.blogspot.com/2011/06/tulip-nebula-sh2-101-scale-in-sky.html
After much much searching, I found that one bright star in the Tulip Nebula is called HD 227018 and, also more searching, that the best place to search for names is Simbad.
Search for an identifier: http://simbad.u-strasbg.fr/simbad/sim-fid
https://simbad.u-strasbg.fr/simbad/sim-id?Ident=%402903862&Name=HD%20227018
The Aladin link gives decent but fuzzy pictures
http://aladin.u-strasbg.fr/AladinLite/?target=LBN%20071.58%2b02.86&fov=0.033334&survey=P%2fDSS2%2fcolor
You can mouse scroll button to zoom in and out
At this scale shown I could finally see some dark areas that sort of match — but not easy way to overlay the images and automatically (or manually) scale them.
Click on the many surveys on the left to see different color filters of the same region. I like the one “PanSTARRS/DR1 color” (some of them give a blank screen).
On the Aladin Lite view of “LBN 071.58+02.86” click on 2MASS survey images on the left. That sets the picture. There should be a floating “Catalogues” box with SIMBAD, Gaia EDR3 and 2MASS survey database identified objects. It looks really busy when you first see all the stars considered important” or noteworth enough to be added to those surveys (maybe they did not put marks on all of them but did survey and catalog). But there is a LOT of empty spots with no boxes.
http://aladin.u-strasbg.fr/AladinLite/?target=LBN%20071.58%2b02.86&fov=0.033334&survey=P%2fDSS2%2fcolor
Now I know how I am going to manage my survey of the universe. But volume and coordinates, not by what is in it. Because each tiny little thing in those pictures is larger than me. LOL!
Richard K Collins, Houston Texas
