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J/A+A/610/L12       KIC 8462852 GTC spectra                    (Deeg+, 2018)

Non-grey dimming events of KIC 8462852 from GTC spectrophotometry. Deeg H.J., Alonso R., Nespral D., Boyajian T. <Astron. Astrophys. 610, L12 (2018)> =2018A&A...610L..12D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, peculiar ; Spectrophotometry ; Spectroscopy Keywords: stars: individual: KIC 8462852 - stars: peculiar - opacity - interplanetary medium Abstract: We report ground-based spectrophotometry of KIC 8462852, during its first dimming events since the end of the Kepler mission. The dimmings show a clear colour-signature, and are deeper in visual blue wavelengths than in red ones. The flux loss' wavelength dependency can be described with an absorption Angstroem coefficient of 2.19±0.45, which is compatible with absorption by optically thin dust with particle sizes on the order of 0.0015 to 0.15um. These particles would be smaller than is required to be resistant against blow-out by radiation pressure when close to the star. During occultation events, these particles must be replenished on time-scales of days. If dust is indeed the source of KIC 8462852's dimming events, deeper dimming events should show more neutral colours, as is expected from optically thick absorbers. Description: Spectra obtained in the follow-up of KIC 8462852 (Boyajian's star) with OSIRIS at the GTC telescope. These spectra have been reduced as described in the paper and are contained in two directories, for target and comparison spectra: sp_target contains spectra of the target star (KIC 8462852) sp_compar contains spectra of the comparison star (KIC 8462763) At each pointing of the GTC, a sequence of 10-45 spectra was generated. The individual spectra are named: tpXXYY.dat for the target spectra and cpXXYY.dat for the comparison spectra, where XX is the pointing number, and YY is a sequence number. The format of each spectrum file is a two-column ascii file: Wavelength (Angstrom) | Flux (arbitrary units)) The files times_pXX.dat correspond to each of the pointings and contain the times of mid-exposure of each spectrum, in the HJD_UTC-2400000 framework. These times apply to both target and comparison spectra and are ordered by increasing sequence number. There are a total of 516 spectra of the target and 516 spectra of the comparison. Objects: --------------------------------------------------------- RA (2000) DE Designation(s) --------------------------------------------------------- 20 06 15.5 +44 27 25 KIC 8462852 = Boyajian's Star 20 06 07.7 +44 26 04 KIC 8462763 = TYC 3162-977-1 --------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 97 16 Observed fluxes at each pointing in five wavelengths bands, indicated by their central wavelengths in nm time_p01.dat 51 10 Pointing 01 times of mid-exposure of each spectrum time_p02.dat 51 45 Pointing 02 times of mid-exposure of each spectrum time_p03.dat 51 45 Pointing 03 times of mid-exposure of each spectrum time_p04.dat 51 33 Pointing 04 times of mid-exposure of each spectrum time_p05.dat 51 30 Pointing 05 times of mid-exposure of each spectrum time_p06.dat 51 35 Pointing 06 times of mid-exposure of each spectrum time_p07.dat 51 30 Pointing 07 times of mid-exposure of each spectrum time_p08.dat 51 31 Pointing 08 times of mid-exposure of each spectrum time_p09.dat 51 44 Pointing 09 times of mid-exposure of each spectrum time_p10.dat 51 31 Pointing 10 times of mid-exposure of each spectrum time_p11.dat 51 19 Pointing 11 times of mid-exposure of each spectrum time_p12.dat 51 24 Pointing 12 times of mid-exposure of each spectrum time_p13.dat 51 30 Pointing 13 times of mid-exposure of each spectrum time_p14.dat 51 35 Pointing 14 times of mid-exposure of each spectrum time_p15.dat 51 31 Pointing 15 times of mid-exposure of each spectrum time_p16.dat 51 43 Pointing 16 times of mid-exposure of each spectrum sp_target/* 30 516 Individual target (KIC 8462852) spectra sp_compar/* 30 516 Individual comparison (KIC 8462763) spectra
See also: V/133 : Kepler Input Catalog (Kepler Mission Team, 2009) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Nr [1/16] Pointing sequential number 3 A1 --- n_Nr [ab] Note (1) 5- 14 F10.4 d BJD Observation central time of each pointing (BJD-2400000) 16- 21 F6.4 --- F556 Observed normalized flux in 556um band 23- 28 F6.4 --- e_F556 rms uncertainty on F556 30- 35 F6.4 --- F618 Observed normalized flux in 618um band 37- 42 F6.4 --- e_F618 rms uncertainty on F618 44- 49 F6.4 --- F709 Observed normalized flux in 709um band 51- 56 F6.4 --- e_F709 rms uncertainty on F709 58- 63 F6.4 --- F792 Observed normalized flux in 792um band 65- 70 F6.4 --- e_F792 rms uncertainty on F792 72- 77 F6.4 --- F868 Observed normalized flux in 868um band 79- 84 F6.4 --- e_F868 rms uncertainty on F868 86- 97 A12 --- FileName Name of the table with times of mid-exposure of each spectrum for this pointing
Note (1): Notes as follows: a = Data not used in analysis due to large scatter from varying exposure times b = Data not used due to poor sky transparency
Byte-by-byte Description of file: time_p*.dat
Bytes Format Units Label Explanations
4- 25 F22.16 d BJD Time (BJD-2400000) 27- 38 A12 --- spTarget Name of the target spectrum name in subdirectory sp_target 40- 51 A12 --- spComp Name of the comparison spectrum name in subdirectory sp_compar
Byte-by-byte Description of file: sp_compar/* sp_target/*
Bytes Format Units Label Explanations
3- 15 F13.7 nm lambda Wavelength 17- 30 F14.7 --- Flux Flux in arbitrary unit
Acknowledgements: Roi Alonso, ras(at)
(End) Patricia Vannier [CDS] 16-Jan-2018
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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