On this page a 25°×35° wide-field view of the Milky Way in the constellations Taurus, Auriga and Perseus is presented in different color composites.
The region south of the galactic plane is full of Molecular clouds.
Click on the images to load a full resolution version with more than 100 megapixels using a JavaScript viewer.
Selected details
Here are a few details that also can be seen using the JavaScript viewer.
Discoveries
The views above show many nebulae that cannot be found in catalogs. (The JavaScript Viewer allows identifying objects using catalogs or SIMBAD and defining new objects.)
Some (probably not all) of these unexplored nebulae have been collected in the list below. Click on the following links for a presentation.
Objects that are not cataloged by now and objects the are related to them. The list does not contain objects that are only minor extensions of known structures.
Uncataloged HII rings and arcs. Some of these structures may be random, some may be projections of spherical shells (bubbles).
Such structures are always circular in the image because stereographic projection was used.
The outlines of these structures (all but CA1) are completed to circles.
It may be helpful to toggle these plots on and off by pressing the '2' key in order to improve the visibility.
In the JavaScript viewer, the object outlines can be toggled on and off by pressing the '2' key. This can be helpful to make certain structures (e.g. rings) visible.
False color images containing H-alpha and continuum:
False color images containing H-alpha and continuum:
H-alpha is mapped to red, blue continuum is mapped to green, and red continuum (without H-alpha) is mapped to blue.
Color of molecular clouds and reflection nebulae in the false color image is something between green (bluish in reality) and blue (reddish in reality).
HII regions (ionized hydrogen) appear red to orange, depending on the amount of OIII (doubly ionized oxygen) detected by the blue continuum filter.
HII regions can be obscured (i.e. their radiation is scattered and/or absorbed) by molecular clouds that lie in front of them. However, emission nebulae do not obscure molecular clouds.
This means that a HII region lies farther away if it appears to be hidden by a visible molecular cloud or a dark nebula. If molecular clouds and HII regions look somehow mixed (pinky red), the HII region is either nearer, or the molecular cloud is very thin.
The latter aspect is the reason why it is difficult to determine whether an unobscured HII region lies in front of the molecular cloud.
An improved visualization of the correlation between HII regions and molecular clouds is planned as soon as better data are available, namely NIR data, which better indicate regions that are optically thick for H-alpha emission.
SIMBAD queries for certain object types can be made easily in the JavaScript Viewer by drawing a circle and pressing a shortcut key or via the menu
A repository with the discoveries can also be found on GitHub
Image data
Images where captured with a camera array which is described on the instruments page.
Image data are:
Projection type:
Stereographic
Center position:
RA: 4h36', DEC: 32°
Orientation:
Above:
North is right
JavaScript viewer:
North is up
Scale:
10 arcsec/pixel (in center at maximum resolution)
FOV:
35°×25° (RA×DEC, through center)
Exposure times:
Sum of exposure times of all frames used to calculate the image.
H-alpha:
7.4 d
Continuum channels:
5.8 d
Image processing
All image processing steps are deterministic, i.e. there was no manual retouching or any other kind of non-reproducible adjustment. The software which was used can be downloaded here.
Image processing steps where:
Bias correction, dark current subtraction, flatfield correction
Alignment and brightness calibration using stars from reference image
Stacking with masking unlikely values and background correction
Star subtraction
Denoising and deconvolution both components (stars and residual)
RGB-composition (same factor for stars and residual for the true color composite)
Dynamic range compression using non-linear high-pass filter