Are you sitting comfortably? Then I’ll begin...
GAIA EDR3 has been released. Below is how to fetch that data from VizieR on the fly with GUIDE planetarium software and display the stars, with a guess to colour from RP and BP (stars will be white if both of those don’t exist) and help on position, parallax and proper motions as well as including the GAIA DR2 ported over radial velocities (there are no new ones in EDR3). Just about the rest of the data in EDR3 is cross identifications to other big surveys and technical data. Note I’ve also not included error values, the general level of accuracy in GAIA is such that the vast majority of errors are negligible compared to what the vast majority of people need as long as you don’t go down to the faint ends of below 17th magnitude and even lower. The faintest end of any survey is always suspect, but those objects are at the system’s absolute limit.
IMPORTANT :- Guide downloads objects based on the area of the field at the LEVEL you are currently displaying. If you use too big a level the sheer amount of data in EDR3 will lead to an immense file, a potential slowdown of either the internet during data retrieval or in GUIDE as it tries to plot them all, so be careful and rarely if ever go above a 1 degree field. You’ll also be needlessly thrashing the VizieR servers, which is impolite. I’ve set the TDF that it will only display at fields of one degree or less anyway.
Now, how to do it.
In your GUIDE directory you will find the following two files, download.txt and toolbar.dat. There were slight changes to how the latter worked over time but I believe it remained backwardly compatible. I run Guide 8 under Guide 9.0 software, as you could update Guide 8 with Guide 9 simply by copying the software over it, even though the data disks differed.
You load download.txt into a text editor. To keep it simple we will replace a needless entry. There should be one starting with the number 2799 for SDSS5 data, that is now out of date and much superseded, so it can harmlessly be replaced, it is doubtful anyone is using it. With the editor change that line for this one :-
2799 -cI/350/gaiaedr3&-out=RA_ICRS,DE_ICRS,Plx,pmRA,pmDE,Gmag,BPmag,RPmag,RVDR2 g.dat
which is one line. Check the column line up with other entries in the file. Deactivated lines start with a # symbol, so those are offset by one column. You need to ensure this one is activated so ensure the lined doesn’t start with a # symbol.
Now save the file back into the guide directory and ensure it has gone there and stayed as “download.txt” and not something daft like “download.txt.txt”, just pressing save instead of save_as should be fine, that’s it, that’s all that’s needed for that bit. If there is no 2799 entry, pick another on the list starting with a # symbol that you don’t use, just remember the number at the beginning of the line as it will be needed again in toolbar.dat.
Now, how toolbar.dat works is documented here https://www.projectp...com/toolbar.htm but the basic principal is the number at the beginning of the line should match the number in download.txt. So load toolbar.dat and search for 2799, when you at the line change it so it reads like this
2799 !gaia3.bmp GAIA EDR 3 data from Vizier
notice that there are three preceding spaces and it does NOT start with a #, which again would deactivate it. All you’ll really be doing is changing the .bmp name and the English description.
If you had to use another number from download.txt search for that entry instead. You can add lines but then you have to adjust an incremental number and you may also end up choosing a number that already exists so it is far, far easier to replace one that already exists in download.txt but isn’t needed.
You need a toolbar button image, so in the spirit of xmas come early, I’ll attach a simple .bmp file which must be saved into the GUIDE directory as “gaia3.bmp” and only that else it won’t be found. There is no large button, you’ll have to make your own, and it simply says GAIA3 as there is no room to pixel edit in all the letters for GAIAEDR3.
Now for the tdf, cut and paste the following in a text editor and ensure it is saved in the Guide directory as “GAIAEDR3.tdf” and not GAIAEDR3.tdf.txt or any other daft variation winblows might try to force on you in default mode in later versions.
-----------copy and paste from next line--------------------
title GAIA EDR3 from VizieR
RA H 5 11
de d 22 11
mag 73 8
photo B:84,6 V:73,6
~b 2 1 GAIA EDR3\n
~r 5 10 \nRA 2000 %s Dec2000 %[22,10]\n\n
~b 73 8 Gmag %s\n
~b 84 8 BPmag %s\n
~b 95 8 RPmag %s\n
~b 40 11 \nPlx %s mas\n
~b 51 11 \npmRA %s mas/y\n
~b 62 11 pmDE %s mas/y\n
~b106 8 \nRadVel %s km/s\n
~r 2 1 \n^GAIA EDR3//xh ttp://vizier.u-strasbg.fr/viz-bin/VizieR-5?&-source=I/350/gaiaedr3&-c=%[5,9]%%20%[22,9]&&-c.eq=J2000.0&-oc.form=deg&-c.r=0.05&-c.u=arcmin&-c.geom=r&-sort=_r&!-4c=Find%%20Data^\n
field 0.00 1.00
mag lim -29
--------------------------------------copy and past only to the line previous------------------
Please note that the line beginning ~r 2 1 and ending in \n is all on just one line, in case of wordwrap, and is followed by a blank line which itself is followed by the line epoch 2000, so correct that if needs be. Also I had to add a space in http (so it reads h ttp instead of http) to stop the editor forcing it to be a compressed actual link instead of text, so that superfluous space will also need to be deleted after you've pasted into a text editor.
Launch Guide. Find a field of interest and zoom into a 1 degree or less field size.
Your toolbar button should have appear for use, if you can't read the details on it hovering overthem should popup a tooltip with their descriptions from toolbar.dat.
Click on the GAIA3 one (ensuring you’re connected to the internet of course...). It should go fetch the data from the internet, if vizier is up. A file called g.dat will be generated in Guide if it works, and if that is there have a look at it in a text editor to ensure it is not an empty file, that there is tabular data in it. If it isn’t there check your download.txt and toolbar.dat. Also, whether or not it downloads from VizieR may very well depend on your system and how GUIDE uses inbuilt aspects of winblows to retrieve the data from the internet, and also as versions of winblows progress you can end up stymied by permissions and firewalls that weren’t an issue in earlier incarnations, so if the download and toolbar files are correct and it hasn’t worked it may be due to your specific setup, and I’m not a computer guru so I won’t be any help. If you get a file in the GUIDE directory called g.dat then something went to the internet, as long as it is not 0 bytes big (of course you have to make sure you are in a field with stars in them before you download)!
Goto ‘Toggle User Datasets’ via the menu, it’s under EXTRAS. Scroll down to the GAIA EDR3 from VizieR entry (alphabetical listing) and double click on in it and then turn it on, even if it already is asterixed to say it is on. Some tdf files work automatically in Guide, some don’t. In this instance when you first use it there is no g.dat until you have pressed a toobar button, so it may be on but not aware there is any data until you double click it on again. Or try just relaunching after downloading the data as that sometimes fixes it. There has to be stuff to find for it to find it...
You will get stars of attempted colour (sometimes overlying almost exactly stars already plotted in Guide, so you might have to press NEXT in on right click to get at the EDR3 info). Right clicking and clicking on More Info gives magnitudes, parallax, proper motions (I’ve not included “total proper motion”, there are limitations on line length in download.txt and anyway it’s useless without Position Angle) and DR2 radial velocity if any. If RP and BP exist Guide will guess a colour to plot the star as, it’s a guess but not exact, pale yellow might actually be yellow, and sometimes you’ll get an orange hue for a yellow or red hue for an orange, due to the borders of the numbers as that GUIDE feature was originally set up for the B-V system, not BP-RP, but it works to some extent. If there is no RP and/or BP magnitudes the star is plotted white. If nothing is plotted there is no Gmag. The data are there and right click on the position would show then, but the star isn’t displayed as there is no Gmag to plot to.
The stars are plotted to Equinox J2000 BUT to the 2016.0 epoch of EDR3, and not to the epoch of J2000, so they may not exactly match any field star from any another source that is plotted to Epoch and Equinox J2000 in GUIDE. If you don’t understand that, don’t worry, just realise that if a star has high enough proper motion when it is plotted in GUIDE it will have moved on from the GUIDE position due to that proper motion.
More info includes a link at the bottom which will open a browser window with the full GAIA EDR3 details for that star from VizieR. Actually you might get more than one star at times as the search has an arbitrary 3 arcseconds radius.
Finally, every time you do this the file g.dat in the guide directory gets more data added to it. You can simply delete this file to start from fresh. Or alternatively, though a little tedious, if there are fields you want to keep then you have to look for their RA and Dec in degrees and delete all the entries with different coordinates. A new g.dat, or further g.dat appendments, will occur next time you push the toolbar button.
Is a double star is of reasonably high common proper motion or optical, you may ask? Well, if you have Guide and the internet you can ask EDR3 what the parallax and proper motions are and make your own mind up, or if you want to check the brightness and colours via it (remember, Gmag is a red colour, so near visual when the star is white but progressively brighter than visual the redder the star is, and BP and RP are a blue and a red, not Blue and Red).
This was far quicker to actually do, test and setup as a feature for GUIDE that it was to write this up! I’ve played with it a couple of times, it works, at least on my machine.
And they all lived happily ever after, exclusions apply, warranty limited to 0 years.
Edited by wdstdf, 03 December 2020 - 10:04 AM.