So, while I’m waiting for the components for my “real” photometry system to arrive, I’m capturing images with my Seestar S50. I’m having a problem with determining transformation coefficients and even splitting the color channels. I’m using AstroImageJ. If I calibrate the raw images with flats, darks and biases, I get errors saying: “This image is debayered to colour and no longer raw!” when I try to separate the color channels. I get a similar error in ASTAP. Anyone have a suggestion about separating the color channels for a calibrated image? I’m using N.I.N.A. to aquired the image and calibration frames.
If you have RGB .fit images from your Seestar it may be worthwhile starting with ASTAP.
Display the Stack menu and select the Photometry tab. Load your RGB .fit images and select all of them. Right click anywhere in the list of selected images. The popup menu allows you to extract the green channel or the blue channel or the red channel. When you select one of them, that channel is extracted and the files (TG or TB or TR) added to the same folder as your original RGB images.
After you have extracted (say) the green channel clear the list of images in ASTAP, reload your RGB images then extract the blue channel.
I don’t have a Seestar, but the above process works for me on RGB fits files converted from Canon DSLR RAW images.
Thanks for the reply Roy. Although the Seestar S50 is the camera, I’m using N.I.N.A. to acquire the images. They are not calibrated as they come off the camera. I have used ASTAP to select the color channels on the raw FITS files but if I try to calibrate the images with flats and darks before I split out the color channels, it fails.
I’ll continue to play around with it and see if I can work around it somehow.
Thanks guys, this is helpful. I am taking my first flare images with an ASI533MC Right now.
Most of them are solving as they come in and I am correcting the pointing with the solves. So things are humming along with the new camera and 6"RC. Eventually need simultaneous BVR readings.
Also need to measure the pass band on my UV/IR cut off and get it installed. Hope to get M67 later tonight without it. Later with the bandpass filter. Baby steps.
Getting there, but first need to break out the RGB channels. Will try ASTAP.
Like Roy suggested, look at using ASTAP. That is what I use with my SeeStar S50. If you use a standard field, ASTAP can calculate the transformation coefficients for you, and apply them. You can also incorporate your darks, flats, etc., from NINA in the process (although I haven’t done that). I don’t use NINA, but use “Favorite” in the SeeStar to capture the desired variable. It allow3s me to enter the desired star in J2000 coordinates, and the unit will precess then to JNow. The stars are nicely centered in the field (at least close enough). Good luck.
Hi Scott, Thanks for your suggestions. I’ve used ASTAP to generate transforms from the SA20 field but I don’t trust them because I can’t transform back to comparison star standard V mags. However, I’ve found that my data seems to be much more internally consistent if I defocus the images. I haven’t had a chance to to try that on a standard field yet but I’m optimistic that the results will be better.
Excellent. Out of curiosity, what aperture and annulus are you using? What is your typical stacked exposure time? I will use a stacked image of about 300 seconds (15 stacked 20s images in EQ mode).
I calculated my transformation coefficients on M67, and I am able to get pretty close.
Unfortunately, my weather lately has not been the best.