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CALSPEC Calibration Database

CALSPEC contains the composite stellar spectra that are flux standards on the HST system. All files are in machine independent binary FITS table format. Information about the pedigree of a given spectrum is in the header of the FITS file, which can be read with the IRAF hedit task or by mrdfits.pro in IDL. Table 1 below summarizes this set of standard star spectra. Columns 2-4 give the spectral type, V, and B-V magnitudes of the stars. Column 5 is the computer compatible file name with the plus and minus signs converted to underscores. Thus, the actual CALSPEC file name is the prefix in column 5, plus one of the suffixes in columns 6-9, plus ".fits". For example, a standard that has STIS data is "bd_28d4211_stis_004.fits". More documentation on some of these stars, eg. coordinates, finding charts and spectral types are in Turnshek et al. (1990), Bohlin, Colina & Finley (1995), and Colina & Bohlin (1997). A set of 32 stars for JWST calibration is developed by Bohlin et al. (2017, BOSZ). A BOSZ model at R=300,000 (col. 6) is provided for each of these 32 JWST standards, while a separate file includes the STIS and NICMOS fluxes concatenated with an R=500 BOSZ model for the extrapolation to 32microns (col. 7). Coordinates are in Table 2. Complete proper long names that must be used for a successful Simbad search appear in the final two columns of Table 2.

High fidelity models are available for a few additional stars, as listed in column 6 of Table 1. The modeled IR fluxes for 13 stars are compared to Spitzer IRAC photometry in Bohlin et al. (2011). Models for the three fundamental primary standards GD71, GD153, and G191B2B (Bohlin et al. 2014) are calculated with the NLTE code of Rauch et al. (2013), which includes metal line blanketing for G191B2B. Previous to November 2013, pure hydrogen models calculated with the Hubeny NLTE code were used for all three stars. This change results in a wavelength dependent shift of the HST/STIS flux scale, but by <~1%.

The observational spectra from columns 7-9 can be compared with the models; and in the case of G191B2B, there is ultraviolet line blanketing at the ~1 percent level. The model calculations extend to 30 or 40 microns and cover the long wavelength limits of 2.7 microns for NICMOS, 1.1 microns for STIS and ACS, and >30 microns for some JWST or Spitzer filters. Vega was observed by STIS (Bohlin & Gilliland 2004a) and revised by Bohlin (2007). The composite flux standard alpha_lyr_stis consists of IUE data from 1152-1675A, STIS CCD fluxes from 1675-5350A, and a specially tailored Kurucz 9400K model longward of 5350A (Kurucz 2005). From 900-1152A, the hotter Kurucz (2003) 9550K model is more continuous with the IUE flux. The STIS and ACS observations of the SDSS standard BD+17 4708 are documented in Bohlin & Gilliland (2004b) and are extended to 2.5microns with NICMOS data, while Bohlin & Landolt (2015) present the evidence for variability of BD+17 4708.

Column 7 lists the CDBS suffix names for the standard stars with STIS or NICMOS fluxes (Bohlin, Dickinson, & Calzetti 2001, hereafter BDC; Bohlin 2007). The naming convention in column 7 is _STIS_ for STIS only, _NIC_ for NICMOS only, and _STISNIC_ for stars with both types of spectrophotometry. Even though the column 7 flux distributions are the best observational spectral energy distributions (SEDs), caution is still required, because some SEDs flagged with an asterisk are not entirely from the gold standard STIS or NICMOS data. Additional IUE, FOS, or Oke observations have lower signal-to-noise, wavelength precision, and photometric accuracy, as discussed in BDC. Thus, the fits headers of any SED used for precision science applications should be checked to be certain that the wavelength region of interest is identified as STIS or NICMOS.

Tabulated in column 8 are the next best standard star flux distributions, which are composed of FOS spectra in the UV and Oke spectra at the longer wavelengths. Also appearing in column 8 are the three solar analogs that are comprised of FOS observation but do not have "_FOS" in the CALSPEC file name. The names for the last set of standard stars appear in column 9 of the Table. The application of corrections to the original IUE and optical fluxes produces a consistent set of spectrophotometric standards from 1150 to 9200A (Bohlin 1996 and references therein). This set of standards is composed of IUE+Oke data only.

CALSPEC also contains the ultraviolet to near-infrared absolute flux distribution of the Sun (filename: sun_reference_stis_001.fits) to 2.7 microns. The solar reference spectrum combines absolute flux measurements from space and from the ground with a model spectrum for the near-infrared (Colina, Bohlin, & Castelli 1996). The newer absolute solar flux measurements of Thuillier (2003) from 1990-23975A, the composite of Rieke et al. (2009), and the solar model from the website of R. Kurucz are additional choices for a solar reference spectrum.

The order of preference for the choice of a standard flux distribution is from left to right in the Table, i.e. from the best in column 7 to the last choice with the lowest quality in column 9.

Also in the CALSPEC data directory are two new products. Rauch et al. (2013) combined FUSE and STIS high resolution spectra of G191B2B ( g191b2b_stisfuse_001.fits); and the covariance matrix ( WDcovar_001.fits) for the uncertainty of the HST flux system as a function of wavelength is included. As explained in more detail by Bohlin et al. (2014), the uncertainty is relative to the reference wavelength of 5556A (5557.5 in vacuum), where this relative uncertainty is zero and the absolute uncertainty is 0.5% (Bohlin 2014).

Table 1: CDBS Files of the Flux(1) Standards with Columns in Order of Preference

Star name    Sp. T.    V     B-V    CDBS name	Model	   STIS        FOS+Oke  IUE+Oke
  [1]          [2]    [3]    [4]       [5]	 [6]	    [7]          [8]      [9]

10 Lac        O9V    4.88   -0.21  10lac       _mod_001  _stis_004
1732526       A4V    12.53   0.12  1732526     _mod_001	 _stisnic_004
1740346(2)    A6V    12.48   0.20  1740346		 _stisnic_003
1743045       A8III  13.52   0.28  1743045     _mod_001	 _stisnic_004
1757132       A3V    12.01  -0.10  1757132     _mod_001	 _stis_004
1802271       A2V    11.98   0.08  1802271     _mod_001	 _stisnic_004
1805292       A4V    12.28   0.14  1805292     _mod_001	 _stisnic_004
1808347       A3V    11.69   ...   1808347     _mod_001	 _stis_004
1812095       A5V    11.74   0.20  1812095     _mod_001	 _stisnic_004
1812524       A4V    12.27   0.18  1812524		 _nic_004
2M0036+18     L3.5   21.34   ...   2m003618		 _stisnic_006
2M0559-14     T4.5   I=19.14	   2m055914		 _stisnic_006
AGK+81 266    sdO    11.95  -0.36  agk_81d266		 _stisnic_006*  	 _005
ALPHA LYR     A0V     0.031  0.00  alpha_lyr   _mod_002  _stis_008*		 _004
BD+02 3375    A5      9.93   0.45  bd02d3375		 _stis_003
BD+17 4708(3) sdF8    9.47   0.44  bd_17d4708		 _stisnic_006
BD+21 0607    F2      9.22   0.44  bd21d0607		 _stis_003
BD+25 4655    B0      9.69  -0.31  bd_25d4655					 _002
BD+26 2606    A5      9.73   0.39  bd26d2606		 _stis_003
BD+28 4211(4) sdO    10.51  -0.34  bd_28d4211		 _stis_004*    _fos_003  _005
BD+29 2091    F5     10.22   0.50  bd29d2091		 _stis_003
BD+33 2642    B2IV   10.83  -0.17  bd_33d2642			       _fos_003  _004
BD+54 1216    sdF6    9.71   0.48  bd54d1216		 _stis_003
BD+60 1753    A1V     9.65   0.07  bd+60d1753  _mod_001	 _stis_004
BD+75 325     O5p     9.55  -0.33  bd_75d325		 _stis_004*    _fos_003  _005
C26202        F8IV   16.64   0.26  c26202      _mod_001	 _stisnic_007
ETA UMA       B3V     1.85  -0.10  etauma		 _stis_003
FEIGE110      sdO    11.83  -0.30  feige110		 _stisnic_006*  	 _005
FEIGE34       sdO    11.14  -0.23  feige34		 _stis_004*		 _005
FEIGE66       sdO    10.51  -0.29  feige66					 _002
FEIGE67       sdO    11.82  -0.34  feige67					 _002
G191B2B       DA.8   11.781 -0.33  g191b2b     _mod_010  _stisnic_006* _fos_003  _005
G93-48        DA3    12.74  -0.01  g93_48					 _004
GD108         sdB    13.56  -0.22  gd108					 _005
GD153         DA1.2  13.346 -0.29  gd153       _mod_010  _stisnic_006  _fos_003
GD50          DA1.2  14.06  -0.28  gd50 					 _004
GD71          DA1.5  13.032 -0.25  gd71        _mod_010  _stisnic_006  _fos_003
GJ754.1A      DBQA5  12.29   0.05  gj7541a		 _stis_003
GRW+70 5824   DA2.4  12.77  -0.09  grw_70d5824           _stisnic_006		 _005
HD009051      G7III   8.92   0.81  hd009051		 _stis_003
HD031128      F4V     9.14   0.41  hd031128		 _stis_003
HD074000      sdF6    9.66   0.45  hd074000		 _stis_003
HD106252      G0      7.36   0.64  hd106252    _mod_001	 _stis_004
HD111980      F7V     8.38   0.53  hd111980		 _stis_003
HD116405      A0V     8.34  -0.07  hd116405    _mod_001	 _stis_004
HD14943       A5V     5.91   0.19  hd14943     _mod_001	 _stis_004
HD158485      A4V     6.50   0.13  hd158485    _mod_001	 _stis_004
HD159222      G1V     6.56   0.65  hd159222    _mod_001	 _stis_004
HD160617      F	      8.73   0.45  hd160617		 _stis_003
HD163466      A6V     6.85   0.19  hd163466    _mod_001	 _stis_004
HD165459(5)   A4V     6.86   0.13  hd165459    _mod_001	 _stisnic_004
HD180609      A0V     9.42   0.15  hd180609    _mod_001	 _stis_004
HD185975      G3V     8.10   0.68  hd185975		 _stis_003
HD200654      G	      9.11   0.63  hd200654		 _stis_003
HD205905      G2V     6.74   0.62  hd205905    _mod_001	 _stis_004
HD209458(6)   G0V     7.65   0.59  hd209458    _mod_001	 _stisnic_007
HD37725       A3      8.31  -0.19  hd37725     _mod_001	 _stis_004
HD37962       G2V     7.85   0.65  hd37962     _mod_001	 _stis_004
HD38949       G1V     7.80   0.57  hd38949     _mod_001	 _stis_004
HD60753(7)    B3IV    6.68  -0.09  hd60753		 _stis_003
HD93521       O9Vp    6.99  -0.27  hd93521		 _stis_004*		 _005
HS2027+0651   DO     16.9    ...   hs2027		 _stis_004
HZ2           DA2.3  13.88  -0.09  hz2  					 _005
HZ21          DO2    14.69  -0.33  hz21 		 _stis_004*		 _005
HZ4           DA3.4  14.51   0.09  hz4  		 _stis_005*		 _004
HZ43(8)       DA     12.91  -0.31  hz43        _mod_010  _stis_004*    _fos_003
HZ43B(8)      M3Ve   14.30   ...   hz43b		 _stis_004
HZ44          sdO    11.67  -0.29  hz44 		 _stis_004*    _fos_003  _005
KF01T5        K1III  13.56   ...   kf01t5		 _nic_003
KF06T1       K1.5III 13.52   0.98  kf06t1	         _nic_003
KF06T2       K1.5III 13.80   1.30  kf06t2      _mod_001	 _stisnic_004
KF08T3       K0.5III 13.18   1.21  kf08t3		 _nic_003
ksi2 Ceti     B9III   4.28  -0.04  ksi2ceti    _mod_001	 _stis_004
LAM LEP       B0.5IV  4.27  -0.23  lamlep      _mod_001	 _stis_004
LB227         DA3.2  15.32   0.06  lb227					 _004
LDS749B       DBQ4   14.674 -0.04  lds749b     _mod_005  _stisnic_006		 _005
LTT9491       DB3    14.10   0.03  ltt9491					 _002
MU COL        O9.5V   5.15  -0.26  mucol       _mod_001	 _stis_004
NGC7293       DAO.5  13.52  -0.36  ngc7293					 _005
P041C(9)      GOV    12.16   0.68  p041c       _mod_001	 _stisnic_007*  _001
P177D         G0V    13.49   0.60  p177d       _mod_001	 _stisnic_007*  _001
P330E         G2V    13.03   0.64  p330e       _mod_001	 _stisnic_008*  _001
SF1615+001A   G      16.75   0.49  sf1615_001a _mod_001	 _stisnic_007
SIRIUS        A1V    -1.46   0.00  sirius      _mod_002  _stis_002*
SNAP-1        sd:B   15.40   0.20  snap1		 _stisnic_006
SNAP-2        G      16.23   ...   snap2       _mod_001	 _stisnic_007
VB8           M7V    16.70   2.0   vb8  		 _stisnic_006
WD0308-565    sdB    14.07  -0.11  wd0308_565  _mod_003  _stis_004
WD0320-539    DA     14.9    ...   wd0320_539		 _stis_004
WD0947+857    DA     16.4    ...   wd0947_857		 _stis_004
WD1026+453    DA     16.13  -0.04  wd1026_453		 _stis_004
WD1057+719    DA1.2  14.68   ...   wd1057_719  _mod_005  _stisnic_006
WD1657+343    DA1    16.1    ...   wd1657_343  _mod_005  _stisnic_006
SUN           G2V   -26.75   0.63  sun_reference	 _stis_002*

* WARNING. Some wavelength coverage from sources of lower precision, such as IUE, FOS, or Oke.
(1)  The unit of flux in all files is erg s-1 cm-2 A-1.
(2)  Dust ring (Bohlin et al, 2011). Variable at +/- 0.01 mag (Pancino et al. 2012).
(3)  BD+17 4708 is variable (Bohlin & Landolt 2015).
(4)  BD+28 4211 has a companion at 2.8arcsec (Landolt & Uomoto (2007).
(5)  Dust ring (Bohlin et al, 2011).
(6)  Transiting Planet.
(7)  No single model fits well in the sense that an unresolved cool companion would explain
	the problem.
(8)  HZ43 and HZ3B are separated by ~3arcsec (BDC).
(9)  P041C has an M companion 0.57arcsec away (Gilliland & Rajan 2011)

Table 2: Coordinates and Alternate Star Names

              R.A.  (2000)  Decl.       PM (mas/yr)       Simbad Name        Alternate Simbad Name
10 Lac      22 39 15.679 +39 03 00.97   -0.32  -5.46  
1732526     17 32 52.574 +71 04 42.74		      2MASS J17325264+7104431	TYC 4424-1286-1
1740346     17 40 34.684 +65 27 14.97		      2MASS J17403468+6527148	TYC 4207-219-1
1743045     17 43 04.48  +66 55 01.6		      2MASS J17430448+6655015
1757132     17 57 13.242 +67 03 40.85		      2MASS J17571324+6703409	TYC 4212-455-1
1802271     18 02 27.17  +60 43 35.7		      2MASS J18022716+6043356
1805292     18 05 29.291 +64 27 51.92		      2MASS J18052927+6427520	TYC 4209-1396-1
1808347     18 08 34.704 +69 27 28.70		      2MASS J18083474+6927286	TYC 4433-1800-1
1812095     18 12 09.604 +63 29 42.16		      2MASS J18120957+6329423	TYC 4205-1677-1
1812524     18 12 52.371 +60 02 31.85		      2MASS J18125240+6002319	TYC 4201-1717-1
2M0036+18   00 36 16.176 +18 21 10.47  883    108     2MASS J00361617+1821104
2M0559-14   05 59 19.143 -14 04 48.88  563   -346     2MASS J05591914-1404488
AGK+81 266  09 21 19.177 +81 43 27.64  -10.70 -49.90  
ALPHA LYR   18 36 56.336 +38 47 01.28  200.94 286.23  
BD+02 3375  17 39 45.596 +02 24 59.60 -364.21  74.81  
BD+17 4708  22 11 31.37  +18 05 34.17  511.8   59.9   
BD+21 0607  04 14 35.516 +22 21 04.26  426.4 -301.49  HD284248
BD+25 4655  21 59 41.975 +26 25 57.40  -37.47 -42.69  
BD+26 2606  14 49 02.357 +25 42 09.16  -9.49 -347.07  
BD+28 4211  21 51 11.021 +28 51 50.36  -35.55 -58.74  
BD+29 2091  10 47 23.163 +28 23 55.92 178.29 -825.37  
BD+33 2642  15 51 59.886 +32 56 54.33  -13.57   0.72  
BD+54 1216  08 19 22.571 +54 05 09.62 -34.95 -628.96  HD233511
BD+60 1753  17 24 52.268 +60 25 50.74   -2.70   2.20  
BD+75 325   08 10 49.488 +74 57 57.92    6.54   8.88  
C26202      03 32 32.84  -27 51 48.6?                 2MASS J03323287-2751483   [B2010] C26202
ETA UMA     13 47 32.438 +49 18 47.76 -121.17 -14.91  
FEIGE110    23 19 58.398 -05 09 56.16  -10.68   0.31  
FEIGE34     10 39 36.740 +43 06 09.26   14.09 -25.01  
FEIGE66     12 37 23.517 +25 03 59.88    3.01 -26.05  BD+25 2534
FEIGE67     12 41 51.791 +17 31 19.76   -6.15 -36.27  BD+18 2647
G191B2B      5 05 30.613 +52 49 51.96   +7.45 -89.54  
G93-48      21 52 25.382 +02 23 19.54  20.25 -304.55  
GD108       10 00 47.254 -07 33 31.01  -38     -4     
GD153       12 57 02.337 +22 01 52.68  -46   -204     
GD50        03 48 50.189 -00 58 32.02   64   -161     
GD71         5 52 27.614 +15 53 13.75   76   -172     
GJ754.1A    19 20 34.923 -07 40 00.07 -60.87 -162.15  
GRW+70 5824 13 38 50.476 +70 17 07.66 -403.65 -22.00  
HD009051    01 28 46.502 -24 20 25.44   52.81 -17.27  
HD031128    04 52 09.910 -27 03 50.95  165.55 -27.75  
HD074000    08 40 50.804 -16 20 42.52 351.36 -484.58  
HD106252    12 13 29.509 +10 02 29.90  23.76 -279.50  
HD111980    12 53 15.053 -18 31 20.00 299.64 -794.83  
HD116405    13 22 45.123 +44 42 53.90    8.15  -8.71  
HD14943     02 22 54.675 -51 05 31.67   22.15  65.77  
HD158485    17 26 04.837 +58 39 06.82   -9.19  13.81  
HD159222    17 32 00.993 +34 16 16.13 -239.8   63.08  
HD160617    17 42 49.324 -40 19 15.53 -61.77 -395.70  
HD163466    17 52 25.374 +60 23 46.95   -1.50  42.50  
HD165459    18 02 30.741 +58 37 38.16  -13.03  24.43  
HD180609    19 12 47.199 +64 10 37.18   -3.53  -7.82  
HD185975    20 28 18.728 -87 28 19.94  168.83 -57.60  
HD200654    21 06 34.750 -49 57 50.28 192.53 -274.00  
HD205905    21 39 10.152 -27 18 23.67  385.21 -84.84  
HD209458    22 03 10.772 +18 53 03.54   28.55 -18.81  
HD37725     05 41 54.371 +29 17 50.92   16.7  -27.8   
HD37962     05 40 51.967 -31 21 03.99 -57.91 -365.20  
HD38949     05 48 20.059 -24 27 49.86  -30.47 -36.46  
HD60753     07 33 27.318 -50 35 03.32   -3.46   5.50  
HD93521     10 48 23.511 +37 34 13.09    0.32   2.44  
HS2027+0651 20 29 32.5   +07 01 08    	...	...   WD2027+068
HZ2         04 12 43.551 +11 51 48.75 -14.65 -209.49  
HZ21        12 13 56.25  +32 56 31.4  -107     28     
HZ4         03 55 21.99  +09 47 18.0   168      4     
HZ43        13 16 21.853 +29 05 55.38 -157.96 -110.23 
HZ43B       13 16.4      +29 06 		      
HZ44        13 23 35.258 +36 07 59.51  -61.60  -3.10  WD1321+36
KF01T5      18 04 03.889 +66 55 43.80	              2MASS J18040388+6655437	[RMC2005] KF01T5 
KF06T1      17 57 58.49  +66 52 29.4	              2MASS J17575849+6652293	[RMC2005] KF06T1
KF06T2      17 58 37.99  +66 46 52.2	              2MASS J17583798+6646522	[RMC2005] KF06T2
KF08T3      17 55 16.223 +66 10 11.64	 2.6   -5.6   2MASS J17551622+6610116	[RMC2005] KF08T3
ksi2 Ceti   02 28 09.543 +08 27 36.20   41.80  13.55  
LAM LEP     05 19 34.524 -13 10 36.44   -3.30  -4.91  
LB227       04 09 28.889 +17 07 54.27  104    -24     
LDS749B     21 32 16.24  +00 15 14.4  +416    +30     
LTT9491     23 19 35.38  -17 05 28.5   270      0     
MU COL      05 45 59.895 -32 18 23.16  -22.24   2.4   
NGC7293     22 29 38.541 -20 50 13.64   32     -5     
P041C       14 51 57.985 +71 43 17.38  -48.4   18.4   2MASS J14515797+7143173	GSPC P 41-C
P177D       15 59 13.57  +47 36 41.9		      2MASS J15591357+4736419	GSPC P177-D
P330E       16 31 33.82  +30 08 46.5		      2MASS J16313382+3008465	GSPC P330-E
SF1615+001A 16 18 14.23  +00 00 08.63	 4    -12     2MASS J16181422+0000086   [B2010] SF1615+001A
SIRIUS      06 45 08.917 -16 42 58.02 -546.05 -1223.14
SNAP-1      16 29 35.76  +52 55 53.2?	-2    -20     2MASS J16293576+5255532
SNAP-2      16 19 46.11  +55 34 17.8		      2MASS J16194609+5534178
VB8         16 55 35.293 -08 23 40.11 -812.4 -871.2   
WD0308-565  03 09 47.91  -56 23 49.5    	      
WD0320-539  03 22 14.83  -53 45 16.5  	 9    -66     
WD0947+857^ 09 57 54.4    85 29 40.9    	      
WD1026+453  10 29 45.264 +45 07 04.92    	      
WD1057+719  11 00 34.24  +71 38 02.9   -42.9  -24.3   
WD1657+343  16 58 51.120 +34 18 53.29   11    -31     	 		      

History

2009 January Update

The 2009 January CALSPEC delivery encompassed six new models and 22 standard star flux distributions. The switch to TLUSTY203 caused a small change in the continuum fluxes with a 0.3% increase in the 1300A/10000A flux ratio. In a narrow region around 4000A between H-delta and H-epsilon, the new models are up to ~0.9% fainter. The correction of a V bandpass error made all stars fainter by a constant 0.35%, independent of wavelength. Pure hydrogen NLTE models are provided for the first time for the faint stars WD1057+719 and WD1657+343; and these models include a small amount of interstellar reddening (Bohlin 2007). There is one new standard, HD209458, delivered to CALSPEC for the first time. The G230LB STIS spectra of G191B2B have replaced the FOS fluxes at 1700-3850A, and a lot of new NICMOS observations are included.

2010 February Update

The 2010 February CALSPEC delivery included six revised models, 22 revised standard star flux distributions, and four new SEDs from STIS observations. HZ43 was demoted from its primary standard category some years ago because of its bright cool companion. The revisions to the flux distributions are all generally less than 1%. The main change was driven by the discovery of a small error of ~0.57% in the gain 4 to gain 1 ratio for the STIS CCD (Goudfroiij, et al. 2009). The weighting for the STIS sensitivity is changed from the total counts for each observation to equal weight for each of the three primary standard WDs, regardless of the number of observations. A few stars have additional STIS observations included in their observed average SED. The NICMOS dispersion relations have been updated (Pirzkal, Bohlin, & Thatte 2009). For seven G stars (Bohlin 2010), the observed flux distributions have been extended from the NICMOS long wavelength limit of ~2.5 microns to 40 microns, using the best fitting Castelli & Kurucz (2004) model SED.

2011 December Update

Calibration standard WD0308-565 derived from STIS data was added to the list of CALSPEC data.

2013 November Update

The low dispersion (R~500) CALSPEC database is expanded from 60 to 93 members with 19 new SEDs for JWST flux calibration (programs 12428 and 12682), 13 new southern standards (12813), and one partial flux distribution from the MAST HST archive. The new stars are measured with STIS and have preliminary extensions to 40microns from model atmosphere fits. The basis for the wavelength dependence of the fluxes is switched from Hubeny pure hydrogen to Rauch model atmosphere calculations, and all dependence on ground based V magnitudes is removed. This delivery encompasses an update for 48 stars with STIS or NICMOS spectrophotometry, the 32 new standards with complete STIS coverage, and eta UMa with archival STIS G230LB data. In addition, 8 high fidelity stellar models are new or updated. For the first time, high dispersion observations of G191B2B and an uncertainty covariance matrix are included.

2013 December Update

Added coordinates for Reach et al. (2005) stars to Table 2.

2014 March Update

A STIS flux distribution for the primary IR standard Sirius (Bohlin 2014) is added to CALSPEC with an IUE extension to shorter wavelengths and with a special Kurucz model beyond 1 micron. The specially tailored Kurucz models for both Sirius and Vega, as normalized to STIS, are also now included. Bohlin (2014) reconciled the absolute visible and IR flux measures, resulting in a 5556A flux reduction from 3.46 to 3.44 e-9 erg s-1 cm-2 A-1. Thus, all of the STIS and NICMOS SEDs are reduced by 0.6% at all wavelengths.

2015 January Update

The G750L STIS spectra require a wider extraction width of 11 pixels, resulting in flux changes of up to ~2% (Bohlin & Proffitt 2015).

2015 April Update

The wavelength coverage of P330E is extended to 2000A, and Table 2 is updated.

2017 February Update

32 stars for JWST calibration are re-delivered after fitting models to the STIS & NICMOS SEDs (Bohlin et al. 2017). The R=500 model provides the extrapolation of the data to 32microns, while the pure R=300,000 model is also available here; both models are normalized to the STIS flux distribution at 6000-9000A.

UPDATES: 1996Feb22, 1999Jul19, 2001Jun5, 2004Feb27, 2006Sep1, 2007Oct LDS749B (Bohlin & Koester 2008), 2008Jul Bohlin & Cohen (2008), 2009Jan, 2010Feb, 2011Dec WD0308-565, 2013Nov, 2013Dec, 2014Mar, 2015Jan, 2015Apr, 2017Feb

PLEASE report errors or send comments to bohlin@stsci.edu.

REFERENCES

Bohlin, R.C. 1996, AJ, 111, 1743
Bohlin, R.C. 2000, AJ, 120, 437
Bohlin, R. C. 2007, in The Future of Photometric, Spectrophotometric, and
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   also Astro-Ph 0608715
Bohlin, R. C. 2010, AJ, 139, 1515
Bohlin, R. C. 2014, AJ, 147, 127
Bohlin. R. C., & Cohen, M. 2008, AJ, 136, 1171
Bohlin, R.C., Colina, L., & Finley, D.S. 1995, AJ, 110, 1316
Bohlin, R. C., Dickinson, M. E., & Calzetti, D. 2001, AJ, 122, 2118 (BDC)
Bohlin, R. C., & Gilliland, R. L. 2004a, AJ, 127, 3508
Bohlin, R. C., & Gilliland, R. L. 2004b, AJ, 128, 3053
Bohlin, R. C., Gordon, K. D., & Tremblay, P.-E. 2014, PASP, 126, 711
Bohlin, R. C., & Koester, D. 2008, AJ, 135, 1092
Bohlin, R. C., et al. 2011, AJ, 141, 173
Bohlin, R. C., & Landolt, A. U. 2015, AJ, 149, 122
Bohlin, R. C., Meszaros, Sz., Fleming, S., Gordon, K. D., Koekemoer, A. M., &
	Kovacs, J. 2017, AJ, submitted
Bohlin, R., C. & Proffitt, C. R. 2015, Instrument Science Report, STIS 2015-01,
	(Baltimore:STScI)
Castelli, F., & Kurucz, R. 2004, IAU Symp. No. 210, Modeling of Stellar
	Atmospheres, eds. N. Piskunov, W. Weiss, & D. Gray 2003, poster A20;
	also arXiv:0405.087 [astro-ph]
Cohen, M., Megeath, S.~T., Hammersley, P.~L., Martin-Luis, F., & Stauffer, J.
	2003, AJ, 125, 2645
Colina, L., & Bohlin, R. 1994, AJ, 108, 1931
Colina, L., & Bohlin, R. 1997, AJ, 113, 1138
Colina, L., Bohlin, R.C., & Castelli, F. 1996, AJ, 112, 307
Gilliland, R., & Rajan, A. 2011, Instrument Science Report, WFC3 2011-03, (Baltimore:STScI)
Goudfrooij, P., Wolfe, M. A., Bohlin, R. C., Proffitt, C. R., & Lennon, D. J.
	2009, Instrument Science Report, STIS 2009-02, (Baltimore:STScI)
Kurucz, R. 2003, http://kurucz.harvard.edu/
Kurucz, R. 2005, Vega spectrum at T=9400K, log g=3.90, [M/H]=-0.5,
   and zero microturbulent velocity, personal communication
Landolt, A., & Uomoto, A. 2007, AJ, 133, 768
Megessier, C. 1995, A&A, 296, 771
Oke, J.B. 1990, AJ, 99, 1621
Pancino, E., et al. 2012, MNRAS, 426, 1767
Pirzkal, N., Bohlin, R.,  & Thatte D. 2009, Instrument Science Report, NICMOS
	2009-006, (Baltimore:STScI)
Rauch, T., Werner, K., Bohlin, R., & Kruk, J. 2013, A&A, 560, A106
Reach, W. T., et al. 2005, PASP, 117, 978
Rieke, G. H., et al. 2008, AJ, 135, 2245 
Thuillier, G., Herse, M., Labs, D., Foujols, T., Peetermans, W., Gillotay, D.,
   Simon, P., & Mandel, H. 2003, Sol. Phys., 214, 1
Turnshek, D.A., Bohlin, R.C., Williamson, R., Lupie, O., Koornneef, J., &
   Morgan D. 1990, AJ, 99, 1243

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Last modified, Febuary 2017