Key to the List

Rows

  1. Source IAU name at equinox (2000). Use of this name in OBSERVE fetches RA and DEC at equinox 2000
    PC Position Code for coordinate accuracy. Position change reference
    Oct96 Adoption of Eubanks 1995-1 positions from USNO geodetic observations
    Nov96 G.Taylor A configuration 3.7cm VLA
    Dec96 C.Carilli A configuration 0.7cm VLA
    Jan97 G.Taylor B configuration 3.7cm VLA
    Feb97 G.Taylor B configuration 3.7cm VLA
    Aug99 M.Goss A config 3.7cm VLA confirmed by 6cm VLA
    May00 J.Wrobel A configuration 3.7cm and 6cm VLA
    Dec00 E.Fomalont, VSOP pre-launch survey, 5 GHz geodetic
    Aug01 VLBA Calibrator Survey astrometric positions Alternate name, if any. The alternate name is NOT recognized by OBSERVE. An entry of CJ2 indicates that the source is included in the Second Caltech-Jodrell Bank VLBI survey, and JVAS is the Jodrell Bank VLA Astrometric Survey.
  2. Source IAU name at equinox (1950). Use of this name in OBSERVE fetches RA and DEC at equinox 1950. Secondary alternate name -- not recognized by OBSERVE.


Position Codes

A positional accuracy <0.002 arcseconds
B positional accuracy 0.002 - 0.01 arcseconds
C positional accuracy 0.01 - 0.15 arcseconds
T positional accuracy >0.15 arcseconds

Notes:

  1. For the most accuracy J2000 is strongly preferred (see section 3.2.)
  2. Errors in declination increase in the south, except for A and B calibrators.

 

Columns

Column
1-2 Band and Band code. For 1.3cm use 2cm entry
3-6 Calibrator quality in the A, B, C and D configuration determined using a 50 MHz observing bandwidth:
P <3% amplitude closure errors expected
S 3-10% closure errors expected
W 10-?% closure errors expected. Suitable for calibration of phases only
C Confused
X Do not use. Too much resolution or too weak
? Structure unknown
7 The approximate flux density of the source. Use only as an indicator of the source strength
8-9 CALIB restrictions. These are suggested UVLIMITS in thousands of wavelengths to use in CALIB to avoid data which are contaminated by structure. A UVMIN (Col. 8) generally means the source is confused at short spacings. A UVMAX (Col. 9) generally means the source is resolved at long spacings. Setting WTUV=0.1 in CALIB will help to ensure stability

 

Comments to four calibrators listed below

  1. Although '?' appears in the table for 0038-213 it is likely that the source is a fine calibrator at 20cm in the A and B configurations since it is unresolved at 6 and 3.6cm at similar resolutions. It is listed with a '?' because we have not confirmed its suitability. Many '?' entries can be interpreted in this way.
  2. The X at 20cm C and D configurations for 0038-213 and the UVMIN means that the source is confused at short spacings at 20cm. The source could be used, but gain quality would be poorer.
  3. The source 0714+146 (see below) is only a calibrator at 20cm in the D configuration and in B and C configurations at 90cm. Many similarly extended sources are included in the listings. Most are fairly strong and can be used as bandpass calibrators at 20cm.
  4. The inaccurate position (PC-T) of 0714+146 is not a restriction for 20cm D configuration observing.
  5. Note the apparent conflict in UVLIMITS for 1733-130 at 20cm. This conflict is resolved by noting that two different ranges will allow a valid CALIB solution; the first, valid for the D array, is 0 to 3 k wavelengths; the second, valid for the A array, is 40 k wavelengths to the longest baseline (approximately 180 k wavelengths).
  6. The 2cm listing for 1759+237 has zero flux density and '?' for quality, indicating it has not been observed. Because the source shows a flat spectrum, it is likely to be a good calibrator at 2cm
0038-213   J2000  C 00h38m29.9524s   -21d20'04.027''
0036-216   B1950  C 00h36m00.4390s   -21d36'33.100''
-----------------------------------------------------
BAND        A B C D    FLUX(Jy)    UVMIN(kL)  UVMAX(kL)
=====================================================
 20cm    L  ? ? X X       0.78           10
  6cm    C  S S S S       0.34                      200
3.7cm    X  X S S S       0.22                      200

0714+146   J2000  T 07h14m04.6352s    14d36'20.629''   3C175.1
0711+146   B1950  T 07h11m14.3000s    14d41'33.000''
-----------------------------------------------------
BAND        A B C D    FLUX(Jy)    UVMIN(kL)  UVMAX(kL)
=====================================================
 90cm    P  X S S X          6            1           4
 20cm    L  X X X S       1.90                        4
 
1733-130   J2000  A 17h33m02.7058s   -13d04'49.546''
1730-130   B1950  A 17h30m13.5352s   -13d02'45.837''
-----------------------------------------------------
BAND        A B C D    FLUX(Jy)    UVMIN(kL)  UVMAX(kL)
=====================================================
 20cm    L  S X X P       5.20           40           3
  6cm    C  P P P P       5.00
3.7cm    X  P P S S       5.80           15
  2cm    U  P P P P       3.70
 
1759+237   J2000  C 17h59m00.3527s    23d43'46.974''
1756+237   B1950  C 17h56m55.9320s    23d43'55.800''
-----------------------------------------------------
BAND        A B C D    FLUX(Jy)    UVMIN(kL)  UVMAX(kL)
=====================================================
 20cm    L  S S S X       0.70            6          90
  6cm    C  X S S S       1.00                       90
3.7cm    X  S S S S       0.55
  2cm    U  ? ? ? ?       0.00

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