sdBV pulsators of the original Kepler field

Atmospheric parameters for the pulsating hot subdwarfs Kepler watched, refitted from ground-based spectra on one model grid by one method, so that the seismology has a consistent set to sit on rather than one per paper. The spectra are means of 1–25 exposures from WHT, NOT, LAMOST, KPNO, BOK, INT, BOSS and KECK; at S/N 27–1912 they are several times anything in the survey archives.

24 / 24targets fitted

79spectra on disk

79fits

1912best S/N

The sample

Every well-studied sdBV pulsator in the original Kepler field. Old fit is the published value in sdBVs.csv, from whichever paper and model grid produced it; new fit is this analysis, on the Bamberg v25 grids, one method throughout. The from column names the observation the new fit is quoted from; a row in grey has no fit yet, and its from then names where the published spectrum came from instead, which is where to look for it.

Where a star has more than one spectrum the quoted fit is the one with the smallest residual, named in the from column — not the highest signal-to-noise, and not an average, because averaging fits from spectra of unequal quality buries the good one.

					old fit — as published			new fit — Bamberg v25
star	survey name	KIC	Kp	class	T_eff	log g	log y	T_eff	log g	log n(He)/n(H)	from	ΔT	published
Adamanta	NGC 6791 B4	2438324	18.27	sdBV+dM	24786	5.30	-2.86	25039 ± 582	5.478 ± 0.087	-2.74 ± 0.24	NOT	+253	partial
Adelard	NGC 6791 B5	2437937	17.98	sdBV	23844	5.31	-2.71	24094 ± 632	5.479 ± 0.083	-2.95 ± 0.34	NOT	+250	partial
Bilbo	J19346+4758	10670103	16.53	sdBV	21485	5.14	-2.20	22236 ± 75	5.220 ± 0.010	-2.57 ± 0.03	WHT	+751	baseline reference
Fredegar	NGC 6791 B3	2569576	18.08	sdBV	24250	5.17	-2.81	24845 ± 336	5.356 ± 0.050	-2.64 ± 0.11	NOT	+595	partial
Frodo	J19271+3810	2991276	17.42	sdBV	33900	5.82	-3.10	35053 ± 342	5.973 ± 0.039	-3.42 ± 0.54	WHT	+1153	partial
Hamfast	J19531+4743	10553698	15.13	sdBV+WD	27750	5.45	-2.90	27090 ± 34	5.532 ± 0.006	-2.79 ± 0.02	wht	-660	baseline reference
Largo	J19230+3715	1718290	15.47	BHBV	22350	4.75	-0.40	23202 ± 153	4.917 ± 0.019	-0.59 ± 0.02	WHT-raw	+852	baseline reference
Merry	J19272+3808	2991403	17.14	sdBV+dM	27300	5.43	-2.60	26649 ± 57	5.463 ± 0.010	-2.48 ± 0.03	WHT	-651	partial ○
Mungo	J19265+4930	11558725	14.95	sdBV+WD	27910	5.41	-3.12	27517 ± 33	5.522 ± 0.006	-3.31 ± 0.06	WHT-c	-393	baseline reference ●
Otho	J19095+4659	10001893	15.85	sdBV	27500	5.35	-2.95	27228 ± 87	5.514 ± 0.015	-2.98 ± 0.06	WHT	-272	baseline reference ●
Paladin	J19310+4413	8302197	16.43	sdBV	27450	5.44	-2.56	26535 ± 126	5.456 ± 0.021	-2.54 ± 0.04	WHT	-915	baseline reference
Pippin	J19091+3756	2697388	15.39	sdBV	25395	5.50	-2.77	24434 ± 64	5.464 ± 0.008	-2.89 ± 0.03	WHT	-961	baseline reference ●
Primula	FBS 1903+432	7668647	15.40	sdBV+WD	27700	5.50	-2.65	27565 ± 45	5.616 ± 0.008	-2.53 ± 0.02	WHT	-135	baseline reference
Rorimac	J19023+4850	11179657	17.07	sdBV+dM	26000	5.14	-2.10	26856 ± 59	5.475 ± 0.011	-2.63 ± 0.03	WHT	+856	partial ○
Rosie	KPD 1943+4058	5807616	15.02	sdBV	27100	5.51	-2.90	26953 ± 74	5.549 ± 0.014	-2.79 ± 0.03	BOK	-147	partial ●
Samwise	J19036+3836	3527751	14.86	sdBV	27818	5.35	-2.99	27556 ± 66	5.475 ± 0.013	-2.91 ± 0.05	WHT	-262	baseline reference
Saradoc	J19249+4707	10139564	16.13	sdBV	31859	5.67	-2.20	31647 ± 133	5.726 ± 0.019	-2.19 ± 0.02	NOT	-212	baseline reference
Tobold	2M1938+4603	9472174	12.26	sdBV+dM	29564	5.42	-2.36	28562 ± 33	5.306 ± 0.005	-2.08 ± 0.01	KECK	-1002	work in progress
Will	J18561+4319	7664467	16.45	sdBV+WD	27440	5.38	-2.57	26441 ± 60	5.456 ± 0.010	-2.51 ± 0.03	NOT	-999	baseline reference
non-pulsators
Rudigar	J19368+4201	6614501	16.1	sdB+WD	23700	5.70	—	23281 ± 118	5.779 ± 0.014	-3.55	INT	-419	baseline reference
Balbo	J19076+4218	6848529	10.7	sdB+WD	30560	5.10	-1.59	28631 ± 113	5.187 ± 0.014	-1.61 ± 0.02	WHT	-1929	unpublished
Bandobras	J18431+4259	7335517		sdO+dM	—	—	—	46748 ± 405	5.611 ± 0.023	-2.20 ± 0.05	INT	—	unpublished
Lobelia	J19393+4708	10149211	15.5	sdB+MS	—	—	—	27769 ± 68	5.610 ± 0.011	-2.47 ± 0.03	WHT	—	unpublished
KBS13	J19261+3720	1868650	13.4	sdB+dM	—	—	—	28990 ± 32	5.740 ± 0.008	-1.70 ± 0.01	BOK	—	unpublished

baseline reference means a detailed study with both a full pulsation analysis and dedicated spectroscopy — those mean spectra are the reference points for the sample. partial means the study is early or one-sided: only part of the Kepler data, or no spectroscopy of its own. unpublished means no detailed study of the Kepler data exists: every star here is mentioned in the KepI and KepVI surveys, and a survey mention is not a study. The published value quoted is the detailed paper's, not the survey's — KepI and KepVI usually fitted a single classification spectrum. A ● marks a star whose published value rests on a spectrum that is not on disk here and would have to be asked for; a ○ marks one where better spectra may exist and it is worth asking. Click a name for the details.

WHTNOTLAMOSTKPNOBOKKECKBOSSINT

Every observation in the Kiel diagram, joined per star, with the formal errors drawn. The question the telescopes exist to answer is whether those bars cover the spread between them. The grey curves are the zero-age and terminal-age extreme horizontal branch (Dorman et al. 1993). Drag a box to zoom into the crowd; double-click, Esc or reset to come back out.

The metallicity each spectrum wants when it is fitted as a fourth free parameter, one point per observation, in alphabetical order of target and coloured by telescope as above — hover a point to name it. A point at +1 exactly is on the edge of the delivered range and is a bound, not a measurement.

g modep modebothno pulsations

single+WD+dM+MS

What the photometry adds: the mass the spectral energy distribution gives against temperature, for the 22 stars that have one. Colour is the kind of pulsation, symbol the companion. The dashed line is the canonical core helium-flash mass, 0.47 M_☉; the dotted one is the mean of the fits carrying no quality flag. A hollow symbol is a fit that does carry one — a poor parallax, a bad χ², or a reddening the dust maps will not support — and is not to be read as a measurement. Hover a point to name it.

Observation by observation

reduction

Both switch together: the figures above and the tables below. As reduced is the extracted spectrum with the instrument response still in it; continuum corrected is the reducer's own continuum divided out first. The fitter puts a straight line through the anchors either way, so the difference is what a straight line cannot follow.

The resid column below is the scatter of observed minus model over every fitted line, in per cent of the continuum. It is a better statement of what a spectrum is worth to a fit than its signal-to-noise: S/N is measured pixel to pixel and sees only photon noise, while a spectrum can be quiet between neighbouring pixels and still have the wrong shape across a line. In this set the residual predicts which spectra can carry a fourth parameter and the S/N does not.

Adamanta

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
NOT	30.4	4.50	4.35%	25039 ± 582	5.478 ± 0.087	-2.74 ± 0.24	1.12	1.00 ± 0.55	1.10	+0.08	+0.27

Adelard

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
NOT	32.6	4.50	4.41%	24094 ± 632	5.479 ± 0.083	-2.95 ± 0.34	1.12	1.00 ± 0.58	1.10	+0.06	+0.32

Balbo

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
BOK	1912.0	9.00	1.25%	28378 ± 119	5.096 ± 0.015	-1.50 ± 0.01	7.37	0.59 ± 0.10	6.78	+0.23	+0.64
KPNO	623.3	1.60	1.78%	29215 ± 101	5.085 ± 0.012	-1.79 ± 0.02	4.82	-0.77 ± 0.41	4.83	-0.39	-0.93
LAMOST	256.7	2.50	1.20%	28584 ± 140	5.139 ± 0.015	-1.55 ± 0.04	0.93	—	—	—	—
LAMOST-mean	304.9	2.50	1.20%	28827 ± 118	5.143 ± 0.015	-1.58 ± 0.02	3.88	-0.23 ± 0.26	3.85	-0.17	-0.60
WHT	240.6	3.00	1.14%	28631 ± 113	5.187 ± 0.014	-1.61 ± 0.02	3.19	0.08 ± 0.23	3.15	-0.04	-0.04

T_eff [K]: spread between telescopes 838, median formal error 118 — a factor 7.1.

log g: spread between telescopes 0.102, median formal error 0.015 — a factor 7.0.

log n(He)/n(H): spread between telescopes 0.285, median formal error 0.017 — a factor 16.6.

Bandobras

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
BOSS	67.7	2.00	2.30%	48973 ± 1205	5.746 ± 0.073	-2.40 ± 0.29	0.98	—	—	—	—
INT	177.0	4.32	0.95%	46748 ± 405	5.611 ± 0.023	-2.20 ± 0.05	1.85	0.59 ± 0.18	1.76	-0.43	+0.87
NOT	86.9	6.50	4.03%	43812 ± 638	5.491 ± 0.064	-2.19 ± 0.11	12.65	0.47 ± 0.29	12.49	-0.12	+0.76

T_eff [K]: spread between telescopes 5161, median formal error 638 — a factor 8.1.

log g: spread between telescopes 0.255, median formal error 0.064 — a factor 4.0.

log n(He)/n(H): spread between telescopes 0.210, median formal error 0.107 — a factor 2.0.

Bilbo

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
KPNO	111.6	1.67	1.90%	21579 ± 230	5.192 ± 0.029	-2.56 ± 0.04	1.37	-2.00 ± 2.69	1.36	+0.04	-0.97
NOT	119.6	2.75	1.66%	21356 ± 162	5.247 ± 0.021	-2.57 ± 0.05	1.76	1.00 ± 0.16	1.60	-0.06	+0.53
WHT	208.5	1.81	1.06%	22090 ± 73	5.244 ± 0.009	-2.56 ± 0.03	1.99	0.94 ± 0.08	1.53	-0.02	+0.51
KPNO	116.3	1.66	2.22%	22096 ± 255	5.068 ± 0.031	-2.60 ± 0.05	2.22	-0.54 ± 1.03	2.21	-0.48	-0.79
NOT	120.3	2.76	1.72%	21843 ± 165	5.208 ± 0.021	-2.59 ± 0.05	2.00	1.00 ± 0.15	1.79	+0.00	+0.48
WHT	207.7	1.81	1.07%	22236 ± 75	5.220 ± 0.010	-2.57 ± 0.03	1.98	0.94 ± 0.08	1.52	-0.00	+0.48

T_eff [K]: spread between telescopes 734, median formal error 162 — a factor 4.5.

log g: spread between telescopes 0.055, median formal error 0.021 — a factor 2.6.

log n(He)/n(H): spread between telescopes 0.018, median formal error 0.045 — a factor 0.4.

T_eff [K]: spread between telescopes 393, median formal error 165 — a factor 2.4.

log g: spread between telescopes 0.152, median formal error 0.021 — a factor 7.4.

log n(He)/n(H): spread between telescopes 0.033, median formal error 0.046 — a factor 0.7.

Fredegar

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
NOT	54.9	4.50	2.86%	24845 ± 336	5.356 ± 0.050	-2.64 ± 0.11	1.68	1.00 ± 0.32	1.58	+0.10	+0.30
NOT-1	26.8	4.50	4.74%	23613 ± 752	5.256 ± 0.099	-2.78 ± 0.26	1.16	0.47 ± 0.76	1.16	+0.07	+0.36
NOT-2	38.2	4.50	3.76%	25306 ± 463	5.400 ± 0.071	-2.51 ± 0.16	1.28	1.00 ± 0.49	1.22	+0.09	+0.21

T_eff [K]: spread between telescopes 1694, median formal error 463 — a factor 3.7.

log g: spread between telescopes 0.145, median formal error 0.071 — a factor 2.0.

log n(He)/n(H): spread between telescopes 0.273, median formal error 0.161 — a factor 1.7.

Frodo

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
NOT	39.6	2.28	3.41%	34455 ± 564	5.763 ± 0.069	-2.70 ± 0.20	1.25	0.15 ± 0.54	1.25	-0.04	+0.75
WHT	81.9	3.37	1.72%	35053 ± 342	5.973 ± 0.039	-3.42 ± 0.54	1.19	0.86 ± 0.25	1.14	-0.40	+0.84

T_eff [K]: spread between telescopes 598, median formal error 453 — a factor 1.3.

log g: spread between telescopes 0.209, median formal error 0.054 — a factor 3.9.

log n(He)/n(H): spread between telescopes 0.724, median formal error 0.371 — a factor 2.0.

Hamfast

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
LAMOST	96.5	2.50	1.92%	27504 ± 249	5.439 ± 0.040	-2.67 ± 0.08	0.99	—	—	—	—
kpno	—	—	0.79%	27282 ± 61	5.514 ± 0.011	-2.73 ± 0.03	1.98	0.56 ± 0.11	1.85	+0.10	-0.15
not	—	—	1.11%	26662 ± 82	5.512 ± 0.013	-2.79 ± 0.04	2.24	0.44 ± 0.12	2.17	+0.11	-0.16
wht	—	—	0.63%	27090 ± 34	5.532 ± 0.006	-2.79 ± 0.02	3.16	0.73 ± 0.06	2.63	+0.10	-0.29

T_eff [K]: spread between telescopes 842, median formal error 71 — a factor 11.8.

log g: spread between telescopes 0.094, median formal error 0.012 — a factor 7.8.

log n(He)/n(H): spread between telescopes 0.123, median formal error 0.036 — a factor 3.4.

KBS13

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
BOK	nan	9.00	0.96%	28990 ± 32	5.740 ± 0.008	-1.70 ± 0.01	5.57	-1.52 ± 0.68	5.56	-0.33	-1.00
LAMOST	153.0	2.50	1.06%	29243 ± 152	5.824 ± 0.021	-1.62 ± 0.02	0.98	—	—	—	—

T_eff [K]: spread between telescopes 254, median formal error 92 — a factor 2.8.

log g: spread between telescopes 0.084, median formal error 0.014 — a factor 5.8.

log n(He)/n(H): spread between telescopes 0.075, median formal error 0.018 — a factor 4.1.

Largo

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
LAMOST	79.3	2.50	2.64%	23154 ± 327	4.955 ± 0.044	-0.55 ± 0.03	1.41	0.75 ± 0.22	1.38	-0.34	+0.41
WHT	82.2	1.32	2.13%	23258 ± 154	4.905 ± 0.019	-0.58 ± 0.02	1.35	0.84 ± 0.14	1.30	-0.36	+0.26
WHT-raw	81.8	1.32	2.12%	23202 ± 153	4.917 ± 0.019	-0.59 ± 0.02	1.36	0.83 ± 0.14	1.30	-0.36	+0.27

T_eff [K]: spread between telescopes 104, median formal error 154 — a factor 0.7.

log g: spread between telescopes 0.050, median formal error 0.019 — a factor 2.6.

log n(He)/n(H): spread between telescopes 0.040, median formal error 0.022 — a factor 1.8.

Lobelia

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
KPNO	80.2	1.69	2.36%	29047 ± 268	5.511 ± 0.040	-2.42 ± 0.06	2.01	-1.59 ± 2.28	1.94	-0.42	-0.98
LAMOST	75.9	2.50	2.65%	28452 ± 402	5.597 ± 0.063	-2.40 ± 0.10	0.98	—	—	—	—
NOT	90.9	2.36	1.82%	27332 ± 176	5.603 ± 0.030	-2.42 ± 0.06	1.51	-2.00 ± 1.76	1.50	-0.34	-0.98
WHT	236.0	1.67	0.82%	27769 ± 68	5.610 ± 0.011	-2.47 ± 0.03	1.60	-2.00 ± 0.68	1.52	-0.30	-0.98
WHT-2009	90.8	4.00	2.04%	27740 ± 133	5.518 ± 0.023	-2.41 ± 0.09	2.57	-0.56 ± 0.83	2.57	-0.06	-0.95

T_eff [K]: spread between telescopes 1715, median formal error 176 — a factor 9.7.

log g: spread between telescopes 0.099, median formal error 0.030 — a factor 3.3.

log n(He)/n(H): spread between telescopes 0.068, median formal error 0.062 — a factor 1.1.

Merry

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
NOT	92.3	2.14	2.05%	25708 ± 173	5.396 ± 0.028	-2.61 ± 0.07	1.46	-0.13 ± 0.44	1.46	+0.07	-0.39
WHT	247.1	1.80	1.10%	26649 ± 57	5.463 ± 0.010	-2.48 ± 0.03	2.34	0.64 ± 0.09	2.08	+0.10	-0.19

T_eff [K]: spread between telescopes 941, median formal error 115 — a factor 8.2.

log g: spread between telescopes 0.067, median formal error 0.019 — a factor 3.6.

log n(He)/n(H): spread between telescopes 0.133, median formal error 0.047 — a factor 2.8.

Mungo

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
WHT	396.6	1.86	0.55%	27517 ± 33	5.522 ± 0.006	-3.31 ± 0.06	2.08	0.51 ± 0.06	1.77	+0.04	-0.13
LAMOST	240.7	2.50	1.09%	27483 ± 138	5.525 ± 0.021	-3.16 ± 0.06	0.97	—	—	—	—

Otho

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
NOT	249.2	2.19	1.15%	26830 ± 74	5.455 ± 0.013	-2.92 ± 0.04	2.44	0.66 ± 0.11	2.28	+0.10	-0.03
WHT	136.6	1.74	1.07%	27228 ± 87	5.514 ± 0.015	-2.98 ± 0.06	1.80	0.78 ± 0.14	1.67	+0.10	-0.07
WHT1	93.5	1.63	1.46%	27289 ± 113	5.501 ± 0.020	-2.94 ± 0.12	1.64	0.64 ± 0.21	1.59	+0.06	-0.20
WHT2	73.0	1.68	1.65%	27682 ± 161	5.486 ± 0.030	-2.96 ± 0.12	1.20	0.97 ± 0.31	1.14	+0.11	+0.01

T_eff [K]: spread between telescopes 852, median formal error 100 — a factor 8.5.

log g: spread between telescopes 0.059, median formal error 0.018 — a factor 3.4.

log n(He)/n(H): spread between telescopes 0.062, median formal error 0.090 — a factor 0.7.

Paladin

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
NOT	124.7	2.22	1.49%	26656 ± 122	5.433 ± 0.019	-2.56 ± 0.04	2.06	0.84 ± 0.15	1.95	+0.12	+0.03
WHT	109.5	2.00	1.27%	26535 ± 126	5.456 ± 0.021	-2.54 ± 0.04	1.32	0.47 ± 0.20	1.29	+0.13	-0.14
WHT-2009	57.2	5.00	2.29%	25918 ± 243	5.326 ± 0.042	-2.66 ± 0.14	1.57	1.00 ± 0.35	1.50	+0.08	-0.02
WHT1	77.7	1.85	1.62%	26710 ± 181	5.478 ± 0.032	-2.64 ± 0.07	1.21	0.53 ± 0.30	1.19	+0.14	-0.18
WHT2	58.7	2.03	1.98%	26655 ± 229	5.417 ± 0.039	-2.49 ± 0.08	1.13	0.38 ± 0.39	1.12	+0.13	-0.20

T_eff [K]: spread between telescopes 792, median formal error 181 — a factor 4.4.

log g: spread between telescopes 0.152, median formal error 0.032 — a factor 4.8.

log n(He)/n(H): spread between telescopes 0.171, median formal error 0.073 — a factor 2.4.

Pippin

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
NOT	228.2	2.15	1.20%	23762 ± 117	5.391 ± 0.016	-2.95 ± 0.05	1.82	0.66 ± 0.11	1.69	+0.08	+0.43
NOT-2008	115.9	6.50	1.38%	23768 ± 257	5.331 ± 0.035	-2.75 ± 0.10	1.55	1.00 ± 0.24	1.39	+0.06	+0.38
WHT	274.1	1.85	0.74%	24434 ± 64	5.464 ± 0.008	-2.89 ± 0.03	2.04	0.68 ± 0.07	1.62	+0.06	+0.14
WHT1	110.6	1.67	1.30%	24488 ± 135	5.478 ± 0.018	-2.87 ± 0.06	1.57	0.78 ± 0.14	1.42	+0.07	+0.21
WHT2	109.7	1.53	1.24%	24796 ± 144	5.455 ± 0.019	-2.90 ± 0.06	1.12	0.68 ± 0.17	1.05	+0.08	+0.03
WHT3	114.4	1.47	1.11%	24172 ± 142	5.423 ± 0.019	-2.97 ± 0.07	1.34	0.48 ± 0.15	1.30	+0.07	+0.26
lamost	—	2.50	1.83%	24076 ± 271	5.390 ± 0.034	-2.84 ± 0.07	0.99	—	—	—	—

T_eff [K]: spread between telescopes 1034, median formal error 142 — a factor 7.3.

log g: spread between telescopes 0.147, median formal error 0.019 — a factor 7.9.

log n(He)/n(H): spread between telescopes 0.212, median formal error 0.063 — a factor 3.4.

Primula

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
NOT	355.2	1.98	0.90%	27278 ± 37	5.578 ± 0.006	-2.57 ± 0.02	3.47	0.47 ± 0.07	3.18	+0.07	-0.25
NOT-2008	106.9	4.82	1.80%	27776 ± 238	5.602 ± 0.042	-2.46 ± 0.08	1.21	0.44 ± 0.44	1.20	+0.15	+0.10
WHT	253.3	1.79	0.71%	27565 ± 45	5.616 ± 0.008	-2.53 ± 0.02	1.87	0.68 ± 0.08	1.59	+0.10	-0.16

T_eff [K]: spread between telescopes 498, median formal error 45 — a factor 11.1.

log g: spread between telescopes 0.038, median formal error 0.008 — a factor 4.6.

log n(He)/n(H): spread between telescopes 0.117, median formal error 0.024 — a factor 4.9.

Rorimac

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
WHT	228.1	1.75	0.91%	26856 ± 59	5.475 ± 0.011	-2.63 ± 0.03	1.83	0.42 ± 0.12	1.76	+0.11	-0.29

Rosie

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
BOK	439.8	9.00	1.34%	26953 ± 74	5.549 ± 0.014	-2.79 ± 0.03	6.32	0.54 ± 0.16	5.81	+0.16	-0.23
KPNO	151.2	1.56	1.65%	27149 ± 116	5.439 ± 0.020	-2.71 ± 0.04	2.45	-2.00 ± 1.27	2.41	-0.39	-0.98

T_eff [K]: spread between telescopes 196, median formal error 95 — a factor 2.1.

log g: spread between telescopes 0.110, median formal error 0.017 — a factor 6.5.

log n(He)/n(H): spread between telescopes 0.083, median formal error 0.034 — a factor 2.4.

Rudigar

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
INT	219.7	3.00	1.00%	23281 ± 118	5.779 ± 0.014	-3.55	1.53	—	—	—	—
WHT	74.5	5.00	2.12%	22763 ± 254	5.596 ± 0.034	-3.55	1.59	1.00 ± 0.36	1.45	-0.01	+0.54

T_eff [K]: spread between telescopes 519, median formal error 186 — a factor 2.8.

log g: spread between telescopes 0.183, median formal error 0.024 — a factor 7.5.

log n(He)/n(H): spread between telescopes 0.000, median formal error nan — a factor nan.

Samwise

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
KPNO	190.9	1.73	2.10%	27794 ± 125	5.364 ± 0.022	-2.97 ± 0.06	2.28	-2.00 ± 1.31	2.22	-0.35	-0.99
LAMOST	141.9	2.50	1.37%	27560 ± 172	5.465 ± 0.026	-2.90 ± 0.06	0.99	—	—	—	—
NOT	217.2	2.04	0.89%	27488 ± 78	5.481 ± 0.013	-3.01 ± 0.06	1.41	0.39 ± 0.14	1.38	+0.10	-0.09
WHT	203.0	1.82	0.84%	27556 ± 66	5.475 ± 0.013	-2.91 ± 0.05	1.42	0.64 ± 0.13	1.31	+0.12	-0.00

T_eff [K]: spread between telescopes 306, median formal error 102 — a factor 3.0.

log g: spread between telescopes 0.117, median formal error 0.018 — a factor 6.7.

log n(He)/n(H): spread between telescopes 0.110, median formal error 0.056 — a factor 2.0.

Saradoc

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
NOT	158.8	2.06	1.16%	31647 ± 133	5.726 ± 0.019	-2.19 ± 0.02	2.00	0.49 ± 0.11	1.94	+0.08	+0.47
WHT	71.1	3.42	1.76%	32594 ± 241	5.803 ± 0.038	-2.20 ± 0.07	1.23	0.68 ± 0.23	1.19	+0.04	+0.72

T_eff [K]: spread between telescopes 948, median formal error 187 — a factor 5.1.

log g: spread between telescopes 0.077, median formal error 0.028 — a factor 2.7.

log n(He)/n(H): spread between telescopes 0.018, median formal error 0.049 — a factor 0.4.

Tobold

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
BOK	nan	9.00	1.14%	29002 ± 44	5.513 ± 0.007	-2.26 ± 0.02	5.21	—	—	—	—
KECK	96.5	0.10	1.78%	28562 ± 33	5.306 ± 0.005	-2.08 ± 0.01	1.44	—	—	—	—
LAMOST	268.9	2.50	1.02%	28222 ± 172	5.488 ± 0.024	-2.28 ± 0.05	0.96	—	—	—	—

T_eff [K]: spread between telescopes 780, median formal error 44 — a factor 17.7.

log g: spread between telescopes 0.207, median formal error 0.007 — a factor 28.4.

log n(He)/n(H): spread between telescopes 0.205, median formal error 0.019 — a factor 10.8.

Will

observation	S/N	FWHM	resid	T_eff	log g	log n(He)/n(H)	χ²	Z (4p)	χ² (4p)	He↔Z	T↔Z
KPNO	90.8	1.77	1.93%	26885 ± 192	5.405 ± 0.032	-2.55 ± 0.07	1.46	0.36 ± 0.28	1.45	+0.15	+0.07
NOT	263.8	2.24	0.78%	26441 ± 60	5.456 ± 0.010	-2.51 ± 0.03	1.77	0.50 ± 0.09	1.64	+0.09	-0.13
WHT	109.4	1.98	1.31%	26553 ± 124	5.434 ± 0.021	-2.63 ± 0.06	1.25	0.39 ± 0.21	1.24	+0.09	-0.21
WHT-uncorrected	96.2	1.92	1.37%	26552 ± 128	5.428 ± 0.022	-2.62 ± 0.07	1.19	0.40 ± 0.23	1.17	+0.09	-0.26
WHT0	32.5	2.48	3.37%	27127 ± 333	5.499 ± 0.059	-2.53 ± 0.17	1.40	1.00 ± 0.54	1.39	+0.10	+0.01
WHT1	58.4	1.60	2.05%	26761 ± 179	5.406 ± 0.031	-2.69 ± 0.12	1.34	0.44 ± 0.35	1.33	+0.08	-0.33
WHT2	60.3	1.80	4.41%	26529 ± 215	5.514 ± 0.038	-2.69 ± 0.12	2.16	0.17 ± 0.45	2.15	+0.08	-0.34

T_eff [K]: spread between telescopes 686, median formal error 179 — a factor 3.8.

log g: spread between telescopes 0.109, median formal error 0.031 — a factor 3.6.

log n(He)/n(H): spread between telescopes 0.182, median formal error 0.068 — a factor 2.7.

What the continuum correction does

Shown for every observation reduced both ways, so the effect can be separated from the star. The fitter always puts a straight line through the continuum anchors either side of a line; where the instrument response curves across a window faster than a straight line can follow, that normalisation is wrong and the fit pays for it.

observation	χ² as reduced	χ² corrected	resid as reduced	resid corrected	Δlog g	ΔT_eff
Bilbo / KPNO	2.22	1.37	2.22%	1.90%	+0.124	-516
Bilbo / NOT	2.00	1.76	1.72%	1.66%	+0.038	-487
Bilbo / WHT	1.98	1.99	1.07%	1.06%	+0.025	-146

Bilbo: the spread between telescopes goes from 393 K to 734 K in temperature and from 0.152 to 0.055 dex in gravity. The correction pulls the gravities together and pushes the temperatures apart — dividing by a fitted continuum fixes the local slope under each line, which is what gravity is read from, and throws away the overall shape, which is what temperature is read from.

Only Bilbo has a continuum-corrected reduction on disk; the other two would need one making before the same comparison can be drawn for them.

written by k1page.py · extraction by mkspek, fits by fitk1