Cartes du Ciel is free software released under the terms of the
GNU General Public License
URAT is a follow-up project to the successful UCAC project using the same astrograph but with a much larger focal plane array.
Longer integration times and more sensitive, backside CCDs allowed for a substantial increase in limiting magnitude, resulting in about 4-fold increase in the average number of stars per square degree as compared to UCAC.
Additional observations with an objective grating largely extend the dynamic range to include observations of stars as bright as about 3rd magnitude. Multiple sky overlaps per year result in a significant improvement in positional precision as compared to UCAC.
You can show the URAT1 catalog data for a specific area in Skychart without downloading the full catalog by using the Virtual Observatory interface.
Start by zooming to a small sky area of the northern hemisphere, about 30 arcmin width, use preferably Equatorial coordinates.
Be sure the button “Show Virtual Observatory data” is checked.
Open the menu Setup → Catalog → VO Catalog, click the Add button.
The chart now show the URAT1 stars for the selected area.
Save the program options to keep your VO catalog definition for a next time.
To show the stars for another area, open the menu Setup → Catalog → VO Catalog (or right click the “Show Virtual Observatory data” button).
Then click the reload arrow on the right column. When the download is finished click the OK button.
Before to start check you have enough disk space available. There is about 17 GB of file to download, then it require 50 GB for the extracted data, and finally 5.8 GB for the Skychart catalog with only a minimal set of data without index.
Download the data, software and documentation from ftp://cdsarc.u-strasbg.fr/pub/cats/I/329/URAT1/ , for example:
mkdir URAT1 cd URAT1 wget --mirror ftp://cdsarc.u-strasbg.fr/pub/cats/I/329/URAT1/ mv cdsarc.u-strasbg.fr/pub/cats/I/329/URAT1/* . cd ..
cd URAT1/access gfortran -o v1dump v1dump.f v1sub.f cd ../..
For convenience for Windows users you can also download a precompiled v1dump.exe
Run v1dump to extract the data from the binary files to a new “asc” directory. Response to prompt are in bold.
cd URAT1 mkdir asc cd access ./v1dump
dump URAT binary data to ASCII hit "enter" to accept defaults or enter new values path input = /d01/urat/v12/
binary data are stored in LINUX-style sequence some computers (PC-style) need a byteflip byte flip (Y/N) ? N
path output= ./
first, last zone (326..900) to handle now = 326 327
enter column separator character (default = blank) begin read file = ../v12/z326 ... output to = ../asc/z326.asc ... ... output to = ../asc/z900.asc cd ..
Download the example project file for Skychart Catgen from http://www.ap-i.net/pub/skychart/urat/urat1.prj.zip
Then use Catgen to convert the text files to a binary catalog optimized for chart display.
cd URAT1 unzip urat1.prj.zip mkdir cat ulimit -S -n 20000 skychart Menu : Setup / Catalog / Catalog - Catgen, Load Project -> urat1.prj
If you use Linux or Mac OS, be sure to read the specific notes in the Catgen documentation page.