Synphot Data User's Guide

A.4 The Stellar Spectral Flux Library by Pickles 1998

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This library of wide spectral coverage, consists of 131 flux calibrated stellar spectra, encompassing all normal spectral types and luminosity classes at solar abundance, and metal-weak and metal-rich F-K dwarf and G-K giant components. Each spectrum in the library is a combination of several sources overlapping in wavelength coverage. Pickles has followed precise criteria to combine sources and to assemble the most reliable spectra. As part of the selection criteria prior to combination, all input sources were checked against the SIMBAD database and against the colors and line strengths as derived by the observed spectra themselves to make sure they had similar spectral types. As a result, this library provides an uniform and complete flux library of observed spectra representing normal stellar types over an uniform grid.

In the following, the list of the above mentioned input sources is given, numbered following Table 1 in the original paper.

1. Sviderskiene (1988, Bull. Vilna. Astron. Obs. 80, 1)
2. Heck et al. (1984, ESA SP-1052)
3. Gunn and Stryker (1983, ApJS 52, 121)
4. Kiehling (1987, A&A 69, 465)
5. Jacobi, Hunter and Christian (1984, ApJS 56, 257)
6. Silva and Cornell (1992, ApJS 81, 865)
7. Pickles (1985, ApJS 59, 33)
8. Pickles and van der Kruit (1990, A&A 84,421)
9. Serote Roos, Boisson and Joly (1996, A&A 117, 93)
10. Danks and Dennefeld (1994, PASP 106, 382)
11. Lancon and Rocca-Volmerange (1992, A&A 96, 593)
12. Dallier, Boisson and Joly (1996, A&A 116, 239)
13. Kleinmann and Hall (1986, ApJS 62, 501)
14. Cohen et al. (1995, 1996a, 1996b, AJ 110, 275; AJ 112, 241; AJ 112, 2274)
15. Fluks et al. (1994, A&AS 105, 311)

Table A.8 of Pickles (1998) precisely identifies what of the above sources entered the combination to create the complete set of spectral types. The output wavelength grid was chosen to be 1150-25000 Angstrom, with a sampling interval of 5 Angstrom per pixel and resolution of ~500 Angstrom. In the end, two separate libraries were created, UVILIB and UVKLIB, that cover the spectral range 1150-10620 Angstrom, and 1150-25000 Angstrom, respectively. In fact, only half of all spectral types in the library (mainly later types of solar abundance) have longer spectral coverages available.

Table A.8 gives an idea of the spectra available. Spectra are ordered by progressive number, according to the spectral type (decreasing effective temperature) and luminosity class. The same ordering sequence is valid for both the UVILIB and the UVKLIB libraries, where the suffix "uk" differentiates between two spectra of the same spectral type but with different wavelength coverage (as described in the next section).

Table A.8: Pickles Library Spectra:

Spectrum ID no.	Spectral Type and Luminosity Class
1-45	O5-M6 V
46-59	B2-K3 IV
60-105	O8-M10 III
106-113	B2-M3 II
114-131	B0-M2 I

A.4.1 The HST/CDBS Version of the Pickles Library

The library installed in CDBS and distributed within STSDAS was obtained from http://cdsarc.u-strasbg.fr/viz-bin/ftp-index?J/PASP/110/863. This library is divided in 2 independent subdirectories, according to spectral coverage, and exactly reproducing the structure of the original library by Pickles. Subdirectory dat_uvi groups all spectra derived from all ultraviolet, optical and near infrared sources, in the wavelength range 1150-10620 Angstrom. This library has complete spectral coverage for all components over this wavelength range, and is (in the original library) referred to as UVILIB. Subdirectory dat_uvk groups all spectra that were derived by combining the UVILIB spectra with additional infrared data to a long wavelength limit of 25000 Angstrom. This is originally referred to as UVKLIB. Within each subdirectory each spectrum is given in FITS table format: the first column gives the wavelength for the given spectral range, and the second column gives the flux. Fluxes are tabulated in units of
erg s^-1cm^-2Å^-1 and were calculated by normalizing the original fluxes in the Pickles V band to a 0 magnitude in vegamag. In the vegamag system, Vega has magnitude zero in all passbands.

For the UVILIB spectra, the names of the files are given as pickles_ttt.fits where "pickles", for Pickles, is the library identifier and "ttt" is a number ranging from 1 to 131. For the UVKLIB spectra, the names have the format pickles_uk_ttt.fits, following the same nomenclature, and with the suffix "uk" provided as to distinguish them from the shorter wavelength library.

The complete list of stars of different spectral type and luminosity class together with the corresponding Pickles file is presented in Table A.9. The effective temperature information is extracted from Table 2 of Pickles (1998). A "w" or an "r" preceding the spectral type indicates a "weak" or "rich" metallicity in respect to solar.

Table A.9: Spectral Type and Effective Temperature Corresponding to the Pickles Spectra in the Library.

FILENAME	SPTYPE(K)	EFF TEMP.
pickles_uk_1	O5V	39810.7
pickles_uk_2	O9V	35481.4
pickles_uk_3	B0V	28183.8
pickles_uk_4	B1V	22387.2
pickles_uk_5	B3V	19054.6
pickles_uk_6	B5-7V	14125.4
pickles_uk_7	B8V	11749.0
pickles_uk_9	A0V	9549.93
pickles_uk_10	A2V	8912.51
pickles_uk_11	A3V	8790.23
pickles_uk_12	A5V	8491.80
pickles_uk_14	F0V	7211.08
pickles_uk_15	F2V	6776.42
pickles_uk_16	F5V	6531.31
pickles_uk_20	F8V	6039.48
pickles_uk_23	G0V	5807.64
pickles_uk_26	G2V	5636.38
pickles_uk_27	G5V	5584.70
pickles_uk_30	G8V	5333.35
pickles_uk_31	K0V	5188.00
pickles_uk_33	K2V	4886.52
pickles_uk_36	K5V	4187.94
pickles_uk_37	K7V	3999.45
pickles_uk_38	M0V	3801.89
pickles_uk_40	M2V	3548.13
pickles_uk_43	M4V	3111.72
pickles_uk_44	M5V	2951.21
pickles_uk_46	B2IV	19952.6
pickles_uk_47	B6IV	12589.3
pickles_uk_48	A0IV	9727.47
pickles_uk_49	A4-7IV	7943.28
pickles_uk_50	F0-2IV	7030.72
pickles_uk_51	F5IV	6561.45
pickles_uk_52	F8IV	6151.77
pickles_uk_53	G0IV	5929.25
pickles_uk_54	G2IV	5688.53
pickles_uk_55	G5IV	5597.57
pickles_uk_56	G8IV	5308.84
pickles_uk_57	K0IV	5011.87
pickles_uk_58	K1IV	4786.30
pickles_uk_59	K3IV	4570.88
pickles_uk_60	O8III	31622.8
pickles_uk_61	B1-2III	19952.6
pickles_uk_63	B5III	14791.1
pickles_uk_64	B9III	11091.8
pickles_uk_65	A0III	9571.94
pickles_uk_67	A5III	8452.79
pickles_uk_69	F0III	7585.78
pickles_uk_71	F5III	6531.31
pickles_uk_72	G0III	5610.48
pickles_uk_73	G5III	5164.16
pickles_uk_76	G8III	5011.87
pickles_uk_78	K0III	4852.89
pickles_uk_87	K3III	4365.16
pickles_uk_93	K5III	4008.67
pickles_uk_95	M0III	3819.44
pickles_uk_100	M5III	3419.79
pickles_uk_105	M10III	2500.35
pickles_uk_106	B2II	15995.6
pickles_uk_107	B5II	12589.3
pickles_uk_108	F0II	7943.28
pickles_uk_109	F2II	7328.25
pickles_uk_110	G5II	5248.07
pickles_uk_111	K0-1II	5011.87
pickles_uk_112	K3-4II	4255.98
pickles_uk_113	M3II	3411.93
pickles_uk_114	B0I	26001.6
pickles_uk_117	B5I	13396.8
pickles_uk_118	B8I	11194.4
pickles_uk_119	A0I	9727.47
pickles_uk_121	F0I	7691.30
pickles_uk_122	F5I	6637.43
pickles_uk_123	F8I	6095.37
pickles_uk_124	G0I	5508.08
pickles_uk_126	G5I	5046.61
pickles_uk_127	G8I	4591.98
pickles_uk_128	K2I	4255.98
pickles_uk_130	K4I	3990.25
pickles_uk_131	M2I	3451.44

A similar list applies for the UKVKLIB library. For these spectra the names have the format "pickles_uk_ttt.fits". A reduced form of Table A.9 can also be found in the library installed in CDBS and is named pickles.fits for the spectra in dat_uvi, and pickles_uk.fits for the spectra in dat_uvk directory. A "w" or an "r" preceding the spectral type indicates a "weak" or "rich" metallicity in respect to solar.

A.4.2 Use of the Pickles Library with Synphot

Use of these spectra should be exactly similar to other libraries already available in synphot. The desired spectrum is provided in input in any of the synphot tasks as appropriate with no particular syntax.

Table A.10 is an example of a standard header file for the spectrum pickles_uk_51.fits. This spectrum corresponds to a star of spectral type F5IV and covers a range in wavelength of 1150 to 25000 Angstrom as can be assumed by the suffix "uk", which indicates a spectrum of the UVKLIB library.

Table A.10: Header for fits file pickles_uk_51.fits.

1 SIMPLE b T Fits standard 2 BITPIX i 16 Bits per pixel 3 NAXIS i 0 Number of axes 4 EXTEND b T File may contain extensions 5 DATE t '2007-01-11T21:02:21' Date FITS file was generated 6 IRAF-TLM t '16:02:37 (11/01/2007)' Time of last modification 7 COMMENT t FITS (Flexible Image Transport System) format is defined in 'Astronomy 8 COMMENT t and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H 9 ORIGIN t 'STScI-STSDAS/TABLES' Tables version 2002-02-22 10 FILENAME t 'pickles_uk_51.fits' name of file 11 NEXTEND i 1 number of extensions in file 12 COMMENT1 t spectral type: F5IV 13 COMMENT2 t metallicity: solar 14 COMMENT3 t original filename: ukf5iv.dat 15 HISTORY t File created by F.R.Boffi. 16 HISTORY t SEDs from Pickles UVKLIB Library (1998, PASP 110, 863). 17 HISTORY t Wavelength is in Angstrom. 18 HISTORY t Fluxes are tabulated in units of erg/s/cm2/A 19 HISTORY t and were calculated by normalizing the original fluxes 20 HISTORY t in the Pickles V band to a 0 magnitude in vegamag. 21 HISTORY t In the vegamag system, Vega has magnitude zero in all passbands. 22 HISTORY t Please refer to the SYNPHOT manual for further information.

The fluxes were extracted from the original paper and were normalized to V=0 in the Pickles' V band. In this way the spectra were provided in a synphot-friendly format and in the usual units of erg s^-1 cm^-2Å^-1.