“Immediate enjoyment” does not give rise to beauty, since the beauty of a thing is revealed “much later,” in the light of another, through the significance of a reminiscence. Beauty responds to duration, to a contemplative synthesis. Beauty is not the flash or fleeting attraction, but a persistence, a phosphorescence of things. The temporality of beauty is very different from that of the “cinematic parade of things.” The age of haste, with its “cinematic” succession of fleeting presents, has no access to beauty or truth. Only when one stops to contemplate, from an aesthetic retreat, do things reveal their beauty, their aromatic essence. It is composed of temporal sediments that phosphoresce.
— Byung-Chul Han, The Scent of Time, Essay on the Art of Lingering.
— Byung-Chul Han, The Scent of Time, Essay on the Art of Lingering.
Associated Contents
PixInsight Gallery entry with text written by Agustín Núñez
Full-resolution image (192 MB)
We are finally starting to work with our own observatory. The first telescope we installed some months ago is a PlaneWave DeltaRho 350 on top of a 10Micron GM2000 HPS II mount. We plan to do wide-field astrophotography with our 150-megapixel camera. This is an optimal setup for mosaics, and we are presenting the first picture here: a two-panel mosaic of the Andromeda galaxy.
This is a classical target and the fourth time I've imaged it:
Each of those three pictures documents specific characteristics of the galaxy and was shot with very diverse instruments, from a Canon 400 mm lens to a 3.5-meter telescope. The top left one could be seen as the most "generic" picture, but it sets an important point in the development of PixInsight because it was, together with another picture of M42, an image produced in 2006 using the novel HDRMT algorithm, which was applied manually through PixelMath since the tool only existed in my mind at that moment.
The latest picture of M31 was the one on the right, a narrowband H-alpha image of the galaxy that unveils its spiral structure down to the nucleus. Now, we wanted to inaugurate the telescope with an opposite view of the galaxy: a purely broadband picture covering the galaxy, its halo, and the background galaxy field. This new picture will serve as the central image in a future pictorial composition dedicated to the galaxy.
Though I'm leading the image processing part of this project, we all know that the other parts — telescope setup and maintenance, image acquisition, IT infrastructure, etc. — are equally important, so we are working as a team. Apart from me, four others are working on this image: Juan Conejero, Alicia Lozano, Maribel Carracedo, and Ana Carracedo. And, of course, the AstroCamp team and their exquisite location have played a key role in the picture. You can see the picture in high resolution and a related writing by Agustín Núñez at the official PixInsight Gallery.
This image has some features worth highlighting. We haven't acquired exposures with a luminance filter. In fact, we had 90 minutes of luminance for each mosaic panel, but we decided to discard them. Integrating a synthetic luminance using the L, RGB, and infrared masters worsens data quality. This is mainly due to the infrared data, a key component of this picture, and the synthetic luminance, which worsens the visibility of the infrared objects.
The infrared master has been added to the RGB image after color calibration with SPCC using the average spiral galaxy standard white reference. Below you can see a comparison:
We added only the small-sized infrared objects to the RGB to preserve the color calibration of the main galaxies in the picture. As can be seen, the infrared channel produces a huge enhancement of infrared-emitting objects, most of them far galaxies and cold stars of M31.
The background is an important component in this image. Shooting only RGB and IR for 50 hours allows for well-defined colors in every single tiny dot in the picture. For instance, we can distinguish the star colors in a globular cluster orbiting around M31:
The bluish tones of open clusters lying very far from the main spiral arms of the galaxy:
Or the characteristic oxygen emission from some of the planetary nebulae in M31:
All these details rely only on the acquisition methodology and the observing site seeing. No sharpening or deconvolution has been applied to the image, except for the use of BlurXterminator in correct only mode to correct small residual aberrations that we still have at the edges of the field. In fact, the grainy appearance of the image is not noise but stars from M31. They are well defined both in shape and color in the outer halo:
It's important to consider that a machine-learning-based denoising will never work in this kind of image. The random distribution of stars in the galaxy halo is very similar to the random distribution of pure noise. Since these techniques lack a uniform criterion across the image, denoising will inevitably erase the stars of the galaxy, compromising the documentary validity of the photograph.
Instead, we did use the TGVDenoise process. Using this algorithmic noise reduction tool, you can calibrate the denoising threshold on the true background sky to preserve all the stars, which have slightly more contrast than the noise.
Finally, I'm posting some small crops as an invitation to explore the entire image:
This is a picture where beauty is veiled, meant to be discovered outside the realm of time, created to prevent the viewer from appreciating it at first glance. But it is also a picture with a building process conveying nature in all its purity, in the same way we have always understood the practice of this art in the Documentary School of Astrophotography.
