Dear astronomically interested friends around the globe!
Today I would like to introduce you to a very remarkable amateur astronomy project by a German stargazer with whom I have been friends for a long time. The galaxy directories by Wolfram Fischer, who has recently spent some time compiling a list of worthwhile photographic objects in the field of galaxies in the southern sky. A list for the northern sky has already existed for some time.
These directories can be viewed on his website at https://www.astrofotografie-wolfram-fischer.de/Galaxienverzeichnisse/Nord.Sued.htm
What's special about them is that the entries under "Name of Objects" are linked to the corresponding image section of the "Digitized Sky Survey." For the southern sky, there is even a link to the corresponding section of the sky in the "Aladin Lite" sky atlas at the "SIMBAD Astronomical Database."
The site was created with the time and love that only a dedicated amateur astronomer can muster. The great thing is that the Galaxy directories are trilingual. In addition to the German version, there are also English and Spanish versions of these pages. A perfect site for AstronomersWithoutBorders.
Wolfram Fischer is a veteran of the German-speaking astronomy scene. Born in Leipzig in the former GDR, he began systematically interested in astronomy at the age of 13. His first astrophotographs, processed by himself from the very beginning, date back to 1968. He was able to draw on his parents' equipment and darkroom experience.
Northern Galaxy Directory:
https://www.astrofotografie-wolfram-fischer.de/Galaxienverzeichnisse/GxVNn/GxVNn.index.htm
This online directory provides a quick overview of photographically worthwhile extragalactic objects of the northern sky. You will receive numerous object-related information on 910 image fields, mostly in 25'x38' angle format.
The directory presents you with the opportunity to view these image fields directly (follow the links in the 3rd column of the directory). If you want to know more, another link (in the 1st column) will help you, which retrieves the exact coordinates of the data within a radius of 10' (around the center of the image) from the SIMBAD astronomical database. A wonderful instrument for object identification, together with the Interactive Aladin Lite view image field that appears there.The image fields are an extract of many thousands of sighted image files of galaxies from the Digitized Sky Survey (DSS, in the northern sky POSS II) available on the Internet, which is an undertaking that has taken years!
Southern Galaxy Directory:
https://www.astrofotografie-wolfram-fischer.de/Galaxienverzeichnisse/GxVSn/GxVSn.index.htm
This online directory provides a quick overview of photographically worthwhile extragalactic objects of the southern sky. You will receive numerous object-related information on 837 image fields, mostly in 25'x38' angle format.
The directory presents you with the opportunity to view these image fields directly (follow the links in the 3rd column of the directory). If you want to know more, another link (in the 1st column) will help you, which retrieves the exact coordinates of the data within a radius of 10' (around the center of the image) from the SIMBAD astronomical database. A wonderful instrument for object identification, together with the Interactive Aladin Lite view image field that appears there.The image fields are an extract of many thousands of sighted image files of galaxies from the Digitized Sky Survey (Digitized images from large Schmidt telescopes, DSS, in the northern sky POSS II) available on the Internet, which is an undertaking that has taken years!
Detailed explanations for the use of the lists and the abbreviations used therein can be found.
https://www.astrofotografie-wolfram-fischer.de/Galaxienverzeichnisse/GxVNn/Gebrauchsanweisung.e.htm
I would like to point out a few special features of this galaxy list. The distances in the lists are not given in light-years, but rather in light travel times. Furthermore, the redshift z has been corrected for the 3K background radiation.
Light travel time
If you tend to take the light travel time for granted as a distance in light-years, consider the following: In an acceleratingly expanding universe, the equation of light travel time and distance becomes increasingly absurd with increasing redshift! Ideally, the light travel time is equal to the distance in light-years that the light has traveled to reach us. However, this is neither the distance of the object when the light began its journey, nor the distance today, nor is it the time a light signal would need to get there now. Only in cosmological proximity to our Milky Way (up to approximately z = 0.1, light travel time about 1.2 billion years) is this simplified view acceptable, given the uncertainties.
The redshift was not given heliocentrically as usual. Why? The 3K background radiation is the universal inertial frame when it comes to space expansion. Thanks to precise satellite measurements, we now know that we are moving at approximately 620 km/s in a direction opposite to the 3K background radiation. The author therefore used corrected redshifts from NED, in which this motion was factored out. The probability of an approximately correct light travel time is statistically most likely using this method. Unfortunately, we generally do not know the intrinsic speed of galaxies in space and can only obtain an estimate of the light travel time by interpreting z solely as space expansion. In dense galaxy clusters, however, the intrinsic speed can reach up to 1000 km/s. The uncertainty is extremely large, especially for nearby objects. Therefore, the author often used distance information from Wikipedia (there, z is usually corrected to the galactic center).
For background information on the creation of the directory, please refer to the author's website: https://www.astrofotografie-wolfram-fischer.de/Galaxienverzeichnisse/GxVNn/Entstehungsgeschichte.htm
In conclusion, I believe that a directory like this is of great use to astrophotographers who are today very technically well-equipped. These directories, painstakingly compiled with a great deal of experience, can be very helpful in planning and preparing one's own astrophotography projects.
With this in mind, with the support of the AWB community, I hope that these directories will be widely distributed around the globe and thus help Wolfram a little to spread his great work to astronomy enthusiasts. SO PLEASE SHARE THESE LINKS :-)
Incidentally, Wolfram Fischer's excellent website is a rich source of astrophoto-historical developments in the field of amateur astronomy. Of course it’s German written, but Google Translator will help ;-) So enjoy reading it and have fun!
Best regards
Joe