Attn. click above images for complex content
Images below shows a 6.33° × 3.88° large view of the Pleiades, also known as M45.
First figure shows a color composite from SDSS I' (mapped to red), R' (mapped green) and G' (mapped blue) filters.
The Pleiades (M45) are a cluster of young blue stars in a distance of about 430 ly (Light-years). The bluish dust which scatters the light from these stars lies about 1 to 2 ly in front of them, see
. The nebula probably belongs to the Taurus Molecular Cloud which also extends within a distance of about 420 ly to 645 ly, see . The artifacts around the bright stars are are caused by star reduction by factor 10. © Copyright Stefan Ziegenbalg
The difference between the color channel is also visualized in the following figure where the color components from the image above can be compared interactively.
Filter: G' © Copyright Stefan Ziegenbalg
Filter: R' © Copyright Stefan Ziegenbalg
Filter: I' © Copyright Stefan Ziegenbalg
G' R' I'
The following pictures are an attempt to compare the results from the SDSS filters with RGB shots.
Filters: RGB © Copyright Stefan Ziegenbalg
Filters: I'R'G' © Copyright Stefan Ziegenbalg
Click on the picture to toggle between RGB and SDSS I'R'G'.
The image shows a 4.2° × 2.6° large region from the picture from top of this page for which RGB data was available. This data was captured with two D=200mm Newton telescopes and Nikon D800e cameras. The resolution of the larger instrument is higher.Despite of the longer total exposure time (54.4h vs. 17h) the SNR of the RGB data is lower. (Because the RGB image is a 2×2 mosaic and the sensitivity of the QHY600L with SDSS filters is about 4 times higher than the sensitivity of the Nikon sensor with its filter array).But due to the brightness of the nebula this is not visible even at highest resolution.
The RGB data was processed in similar way as the I'R'G' data and benefits from the higher resolution. But compared to the I'R'G' data, the color is poor because the data of the RGB channels is to similar.
FOV: 6.33° × 3.88°
Date: 12/2021 to 01/2022
Location Pulsnitz, Germany
Instrument: 2-3 × Nikon 300mm f/2.8 AF-S
Camera: 2-3 × QHY600L
North is up (exactly)
Scale: 3 arcsec/pixel (at full resolution)
Total exposure times:
SDSS G': 5.0 h
SDSS R': 6.9 h
SDSS I': 5.1 h
All image processing steps are deterministic, i.e. there was no manual retouching or any other kind of non-reproducible adjustment.
Image processing steps where:
Bias correction, dark current subtraction, flatfield correction, noise estimation
Alignment and brightness calibration using stars from reference image
Stacking with masking unlikely values and background correction
Denoising and deconvolution
Dynamic range compression using non-linear high-pass filter
Tonal curve correction
Gibson, S.J.; Nordsieck, K.H. (2003). "The Pleiades Reflection Nebula. II. Simple Model Constraints on Dust Properties and Scattering Geometry". The Astrophysical Journal. 589 (1): 362–377.
P. A. B. Galli 1, L. Loinard 2,3 H. Bouy 1, L. M. Sarro 4, G. N. Ortiz-León 5, S. A. Dzib 5, J. Olivares 1, M. Heyer 6, J. Hernandez 7, C. Román-Zúñiga 7, M. Kounkel 8, and K. Covey, (2019). "Structure and kinematics of the Taurus star-forming region from Gaia-DR2 and VLBI astrometry". Astronomy & Astrophysics 630: A137.