a) UCAC5-TGAS 275 MB, compressed = 100 MB
-------------
column name unit bytes description
--------------------------------------------------------------------------------
1 ra deg TGAS right ascension, epoch 2015
2 dec deg TGAS declination, epoch 2015
3 gmag mag Gaia DR1 G magnitude
4 gjcol mag G - J color index (Gaia G, 2MASS J) or -9.000
5 pmur mas/yr proper motion RA*cosDec from UCAC - Gaia epoch data
6 pmud mas/yr proper motion Dec from UCAC - Gaia epoch data
7 pmgr mas/yr proper motion RA*cosDec copy from Gaia TGAS
8 pmgd mas/yr proper motion Dec copy from Gaia TGAS
9 pmdr mas/yr difference in proper motion pmur - pmgr
10 pmdd mas/yr difference in proper motion pmud - pmgd
11 eur mas/yr formal error of UCAC-Gaia proper motion RA*cosDec
12 eud mas/yr formal error of UCAC-Gaia proper motion Dec
13 egr mas/yr error of TGAS proper motion RA*cosDec
14 egd mas/yr error of TGAS proper motion Dec
15 srcid Gaia source ID
16 na number of all images of UCAC data this star
17 nu number of images used for UCAC mean position
-------------------------------------------------------------------------
Note: nu (col.17) might be 0 in case all images are excluded from the
regular, weighted mean position calculation of all individual epoch
positions. In that case the mean position given in the catalog is
the unweighted mean over all images. Of course those positions,
as well as those for nu = 1 can not be "trusted" as much as nu >= 2
positions.
b) UCAC5 main data (all stars matched, incl. TGAS stars)
------------------ 4.3 GB (4310340520 byte = 107758513 records of 40 byte)
INTEGER*8 srcid
INTEGER*4 ira,idc
INTEGER*2 epu, pmur,pmud, pmer,pmed
. ,gmag,umag,rmag,jmag,hmag,kmag
INTEGER*1 flg, nu
OPEN (22,FILE=fnu5,RECL=40)
READ (22,REC=nu5) srcid, flg,nu,epu ! 8 + 4 12 byte
. ,ira,idc, pmur,pmud, pmer,pmed ! 8 + 4 + 4 = 16 byte
. ,gmag,umag,rmag,jmag,hmag,kmag ! 6 * 2 = 12 byte
item name unit description
-------------------------------------------------------------------------
1 srcid Gaia source ID
2 flg 1 = TGAS, 2 = other UCAC-Gaia star, 3 = other NOMAD
3 nu number of images used for UCAC mean position
4 epu myr mean UCAC epoch (1/1000 yr after 1997.0)
5 ira mas mean UCAC RA at epu epoch on Gaia reference frame
6 idc mas mean UCAC Dec at epu epoch on Gaia reference frame
7 pmur 0.1 mas/yr proper motion RA*cosDec (UCAC-Gaia)
8 pmud 0.1 mas/yr proper motion Dec (UCAC-Gaia)
9 pmer 0.1 mas/yr formal error of UCAC-Gaia proper motion RA*cosDec
10 pmed 0.1 mas/yr formal error of UCAC-Gaia proper motion Dec
11 gmag mmag Gaia DR1 G magnitude (1/1000 mag)
12 umag mmag mean UCAC model magnitude (1/1000 mag)
13 rmag mmag NOMAD photographic R mag {1/1000 mag)
14 jmag mmag 2MASS J magnitude (1/1000 mag)
15 hmag mmag 2MASS H magnitude (1/1000 mag)
16 kmag mmag 2MASS K magnitude (1/1000 mag)
-------------------------------------------------------------------------
c) UCAC5 main data (alternative to "b)": Dec zone files + more Gaia data
------------------ 5.3 GB (5603442676 byte = 107758513 records of 52 byte)
There are 900 individual files (z001 ... z900), each containing stars in
a narrow, 0.2 deg wide Dec zone, beginning at the south celestial pole.
Stars on each "zone file" are sorted by RA. There are 2 index files
(formatted, binary) which go with these (see below).
The data structure is as follows:
INTEGER*8 srcid
INTEGER*4 ira,idc, rag,dcg
INTEGER*2 epi, pmir,pmid,pmer,pmed, phgm,im1,rmag,jmag,hmag,kmag
. ,erg, edg
INTEGER*1 flg,nu1
OPEN (11,FILE=fnu5d,ACCESS='direct',RECL=52)
READ (11,REC=iz,ERR=99) ! total = 52 b
. srcid, rag,dcg, erg,edg ! 8 + 8 + 4 = 20 b
. ,flg,nu1,epi ! 4 = 4 b
. ,ira,idc, pmir,pmid, pmer,pmed ! 8 + 4 + 4 = 16 b
. ,phgm,im1,rmag,jmag,hmag,kmag ! 6 * 2 = 12 b
item name unit description
-------------------------------------------------------------------------
1 srcid Gaia source ID
2 rag mas Gaia RA at epoch 2015.0 (from DR1, rounded to mas)
3 dcg mas Gaia Dec at epoch 2015.0
4 erg 0.1 mas Gaia DR1 position error RA at epoch 2015.0
5 edg 0.1 mas Gaia DR1 position error Dec at epoch 2015.0
6 flg 1 = TGAS, 2 = other UCAC-Gaia star, 3 = other NOMAD
7 nu number of images used for UCAC mean position
8 epu myr mean UCAC epoch (1/1000 yr after 1997.0)
9 ira mas mean UCAC RA at epu epoch on Gaia reference frame
10 idc mas mean UCAC Dec at epu epoch on Gaia reference frame
11 pmur 0.1 mas/yr proper motion RA*cosDec (UCAC-Gaia)
12 pmud 0.1 mas/yr proper motion Dec (UCAC-Gaia)
13 pmer 0.1 mas/yr formal error of UCAC-Gaia proper motion RA*cosDec
14 pmed 0.1 mas/yr formal error of UCAC-Gaia proper motion Dec
15 gmag mmag Gaia DR1 G magnitude (1/1000 mag)
16 umag mmag mean UCAC model magnitude (1/1000 mag)
17 rmag mmag NOMAD photographic R mag {1/1000 mag)
18 jmag mmag 2MASS J magnitude (1/1000 mag)
19 hmag mmag 2MASS H magnitude (1/1000 mag)
20 kmag mmag 2MASS K magnitude (1/1000 mag)
-------------------------------------------------------------------------
d) ASCII index table to zone file data u5index.asc (27 MB)
--------------------------------------
There are 900 zone files (z001 to z900), each 0.2 deg wide in Dec.
There are 1440 bins along each zone file, which is 0.25 deg = 1/60 hour
along RA for each bin.
sample data:
...
15622 2 38 1437
15624 7 38 1438
15631 8 38 1439
15639 10 38 1440
0 11 39 1 -82.2
11 4 39 2
15 4 39 3
...
column data description
-------------------------------------------------------------
1 x0(zn,j) (index of 1st star of zone zn and bin j) - 1
2 xn(zn,j) number of stars in that bin
3 zn zone number (= 1 to 900)
4 j bin number (= 1 to 1440)
-------------------------------------------------------------
The first line of each new zone has the upper bound Declination
(largest Dec in that zone) appended (degree).
e) Index to zone files as binary data u5index.unf (10 MB)
-------------------------------------
INTEGER dimz, jmax, rlidx
PARAMETER (dimz = 900 ! total number of zones
. ,jmax = 1400 ! total number of bins along a zone
. ,rlidx= dimz*jmax*4) ! record length index file (byte)
INTEGER x0(dimz,jmax), xn(dimz,jmax)
OPEN (15,FILE=fnidxu,ACCESS='direct',RECL=rlidx)
WRITE (15,REC=1) x0
WRITE (15,REC=2) xn
Thus the record length of that file is 900 * 1440 * 4 byte = 5184000 byte,
and the total file size is exactly twice of that = 10368000 byte.
The data x0 and xn are explained above in section "d)".
The second record is strictly not needed but convenient for star counting.
f) Gaia - NOMAD data file (additional stars NOT in above 2 catalogs)
-------------------------- 20.5 GB
INTEGER*8 srcid
INTEGER*4 rag,dcg
INTEGER*2 gmag,rmag,jmag, pmnr,pmnd,epm
OPEN (23,FILE=fnpmn,ACCESS='direct',RECL=38)
READ (23,REC=nn)
. srcid,rag,dcg, gmag,rmag,jmag, pmnr,pmnd ! 16+6+4 = 26 byte
. ,epmr,epmd, nepr,nepd, nflg ! 4+4+4 = 12 byte
item name unit description
-------------------------------------------------------------------------
1 srcid Gaia source ID
2 rag mas Gaia position RA rounded to nearest mas
3 dcg mas Gaia position Dec rounded to nearest mas
4 gmag mmag Gaia G-magnitude
5 rmag mmag NOMAD sky survey R magnitude
6 jmag mmag 2MASS J magnitude
7 pmnr 0.1 mas/yr PM from Gaia - NOMAD RA*cosDec
8 pmnd 0.1 mas/yr ... Dec
9 epmr 0.1 mas/yr formal error on PM RA*cosDec
10 epmd 0.1 mas/yr formal error on PM Dec
11 nepr 0.01 yr NOMAD mean epoch for RA (after 1900)
12 nepd 0.01 yr ... for Dec
13 nflg original NOMAD flag I*4 (see NOMAD catalog)
-------------------------------------------------------------------------
