JWST vs amateur setup

James Webb Space Telescope (JWST) was launched in December 2021. In early February 2022 I managed to image its “dance” in the sky with my amateur setup (click here for details). After a long configuration and calibration period that lasted about six months, JWST could snap its first shots of the sky, first released to the public on 12th July 2022.

One of these images is a high-res detail of a rather well-known southern sky object, NGC 3324 (“Gabriela Mistral Nebula”), which is part of the vast Eta Carinae Nebula (NGC 3372) complex.

The very same area of the sky had been imaged by Hubble Space Telescope several years before. A comparison of JWST’s and HST’s images is available at this link. The difference is striking, although one has to bear in mind that the colors of these images are artificial, because the detectors (JWST’s ones even more so) are sensitive to light wavelengths that are completely invisible to the human eye, in particular in the near and medium infrared (wavelengths ranging from 600 to about 5000 nm, i.e. 5 um). For the sake of precision, JWST’s NIRCam camera sensitivity range includes the ionized hydrogen H-alpha band (656.3 nm) in its lower end with its F070W filter. The human eye is anyway not sensitive enough to trigger color perception in diffuse objects, except for the very brightest ones which do not include the target of this image.

It is only by pure chance that I imaged the same nebula, which is visible only from the southern hemisphere, during my May 2021 trip to Tivoli Farm, Namibia. I couldn’t help but wonder if I could spot the area of the Nebula imaged by JWST in my photo, acquired with low-end amateur equipment. To my surprise, the answer is YAY!!, despite the sheer difference in detail. Before viewing the image, there are a few important considerations:

1. JWST’s image has been acquired with the most powerful telescope ever built by mankind, located in space and with a diameter of 6.5 m, i.e. more than 25 times the telescope I used.;
2. Mine is a monochromatic H-alpha channel image (656.3 nm wavelength), whereas JWST’s is false-color multiband;
3. Because JWST’s image was acquired in the IR band, the relative brightness of stars in the field can be much different.

That said, here you go. The first image depicts my large-field 2021 shot, where the area imaged by JWST is marked by a red rectangle. The second image contains a same-size comparison of the two images (JWST’s and mine at full res), and the third one is an animated GIF by Lorenzo Comolli blinking my image and JWST's. There’s no comparison, but one can clearly see that the field of view is the same and some details can even be recognized in both images.