A six-frame HaRGB mosaic. The uploaded image has the original pixel scale, but cropped to 8K size.
Data collection went from July 2022 to Feb 2023, over 30 different nights. L exposures were all taken under moderately good seeing of < 1.5". RVB and Ha exposures were taken under < 2" seeing. Data taken under worse conditions are not used.
There are a couple of large nebulas in M33 known for their cyan-ish colors, like IC 132 and NGC 588. They are cyan-ish likely because of their strong [OIII] emission. However, in this picture, they are rendered orange. This is because of the Johnson filters that we use ( for research). A disadvantage is that the Johnson B filter only very weakly covers the [OIII] emission, unlike the blue filters commonly used for astrophotography. If we use standard photographic filters, [OIII] would be recorded in both green and blue, so it would appear cyan. Here, [OIII] is basically only captured by the V filter (green), so [OIII] appears plain green. However, those nebulas still emits some Ha, which is red. This leads to the orange color, rather than cyan.
I encourage you to open the full-resolution image and make your browser to display it to fit the full screen. Hope you enjoy it.
Rev.B is a 2:3 downsample, showing the whole area of the 2x3 mosaic.
Rev.C is a down-sampled 4K crop with our telescope logo, which can be used as a desktop wallpaper for 2K to 5K monitors. If you don't like the Astrobin watermark, you can download watermark-free versions here:
with logo in the upper-left cornerwith logo in the lower-right corner
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