J/ApJS/249/23 Galactic Plane Infrared Polarization Survey, DR4 (Clemens+, 2020)
The Galactic Plane Infrared Polarization Survey (GPIPS): Data Release 4.
Clemens D.P., Cashman L.R., Cerny C., El-Batal A.M., Jameson K.E.,
Marchwinski R., Montgomery J., Pavel M., Pinnick A., Taylor B.W.
<Astrophys. J. Suppl. Ser., 249, 23 (2020)>
=2020ApJS..249...23C 2020ApJS..249...23C (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Galactic center ; Polarization ; Infrared
Keywords: magnetic fields - starlight polarization - polarimetry - surveys -
interstellar magnetic fields - galaxy disks - Milky Way disk
Abstract:
The Galactic Plane Infrared Polarization Survey (GPIPS) seeks to
characterize the magnetic field in the dusty Galactic disk using
near-infrared stellar polarimetry. All GPIPS observations were
completed using the 1.83m Perkins telescope and Mimir instrument.
GPIPS observations surveyed 76 deg2 of the northern Galactic plane,
from Galactic longitudes 18°-56° and latitudes -1° to
+1°, in the H band (1.6 µm). Surveyed stars span 7th-16th mag,
resulting in nearly 10 million stars with measured linear
polarizations. Of these stars, ones with mH<12.5mag and
polarization percentage uncertainties under 2% were judged to be high
quality and number over one million. GPIPS data reveal plane-of-sky
magnetic field orientations for numerous interstellar clouds for AV
values to ∼30mag. The average sky separation of stars with
mH<12.5mag is about 30'', or about 60 per Planck polarization
resolution element. Matching to Gaia DR2 showed the brightest GPIPS
stars are red giants with distances in the 0.6-7.5kpc range.
Polarization orientations are mostly parallel to the Galactic disk,
with some zones showing significant orientation departures. Changes in
orientations are stronger as a function of Galactic longitude than of
latitude. Considered at 10' angular scales, directions that show the
greatest polarization fractions and narrowest polarization position
angle distributions are confined to about 10 large, coherent
structures that are not correlated with star-forming clouds. The GPIPS
polarimetric and photometric data products (Data Release 4 catalogs
and images) are publicly available for over 13 million stars.
Description:
Descriptions of the motivation, design, and implementation of the data
collection strategies for GPIPS are detailed in the survey
introduction paper (Paper I, Clemens et al., 2012ApJS..200...19C 2012ApJS..200...19C), the
survey calibration paper (Clemens et al., 2012ApJS..200...20C 2012ApJS..200...20C, Paper
II), and the first data release (DR1) paper (Clemens et al.,
2012ApJS..200...21C 2012ApJS..200...21C, Paper III). GPIPS was conducted over more than
400 nights on the 1.83 m Perkins telescope between 2006 and 2019. NIR
polarimetric observations were obtained for overlapping sky fields
spanning Galactic longitudes (GL) of 18°-56° and Galactic
latitudes (GB) of -1° to +1° in the northern, inner Milky Way
disk. Each equatorial-oriented sky field covered one 10x10-arcmin2
field of view (FOV) of the Mimir instrument, pointed toward 1 of 3237
centers on the 9'x9' spaced grid making up GPIPS. The Mimir pixel size
of 0.58x0.58-arcsec2 was designed to adequately sample the ∼1.5"
average seeing at the Perkins telescope site. Each FOV was observed as
96 (or up to 119) individual images, each of 2.5s exposure time. Each
image was taken through 1 of 16 independent rotational orientations of
an internal, cold, half-wave plate (HWP) in Mimir to modulate the
incoming linear polarization for analysis by a fixed, internal, cold
wire grid prior to detection by the 1024x1024-pixel InSb ALADDIN III
array detector. Performing a six-position (or seven-position) sky
dither, with typical offsets of 15''-18'', for each sky field allowed
removal of the effects due to bad or missing detector pixels, boosted
the signal-to-noise ratio (S/N), and provided robustness against a
variety of observing, data, or data-processing problems.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 76 3237 GPIPS field properties summary table
catalog.dat 727 13861329 GPIPS DR4 unique star data file
phot/* . 3237 Individual photometric catalogs for the
3237 GPIPS fields with header
pol/* . 3237 Individual polarisation catalogs for the
3237 GPIPS field with header
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See also:
https://sites.bu.edu/gpips/fov-based-dr4-data-products : GPIPS Home page
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- GPFOV [1/3237] GPIPS FOV serial number
6- 11 F6.3 deg GLON FOV center Galactic Longitude
13- 18 F6.3 deg GLAT FOV center Galactic Latitude
20- 23 F4.1 arcsec CenOff Radial Offset from ideal GPIPS grid center
25- 34 A10 "date" Night Date of Observation (UT Night)
36- 39 I4 --- Image0 First image of Observation
41- 45 F5.3 arcsec FWHM Full-width at half-maximum of mean
stellar profile
47- 49 F3.1 % SAmp Slow variation of sky transmission
(Secular Amplitude)
51- 54 F4.2 % SkyNoise Fast variation of sky transmission
56- 57 I2 --- Nreject Image rejection count
59- 61 I3 --- Ngood Image acceptance count
63 I1 --- PScore Polarization Pattern Evaluation Score
(Pattern Score)
65 I1 --- QCflag [0/4] Overall quality control flag (1)
67- 71 I5 --- Nphot Number of photometric sources in the Field
73- 76 I4 --- Npol Number of polarimetric sources in the Field
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Note (1): Overall quality control flag as follows:
0 = Observation met all of the criteria for PSF quality, Secular
Amplitude, Sky Noise, good image count, and polarization Pattern Score
3 = Pattern Scores being unity or moderately higher Secular Amplitudes and
center position offsets
4 = Pattern Scores are 0
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Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- Seq Sequential number (R.A.-ordered) (NUM)
10- 34 A25 --- GPIPS GPIPS designation, GPIPS_JHHMMSS.ss+DDMMSS.s
(DESIG_GPIPS)
36- 45 F10.6 deg RAdeg GPIPS right ascension (J2000) (RA_DEG)
47- 56 E10.6 deg DEdeg GPIPS declination (J2000) (DEC_DEG)
58- 75 F18.15 deg GLON GPIPS Galactic longitude (GAL_L)
77- 98 E22.18 deg GLAT GPIPS Galactic latitude (GAL_B)
100-138 A39 --- GPSTAR FOVx105 + stellar ID No (GPSTAR) (1)
140-152 A13 --- CAT-FLAG Array of archive catalog match codes
(CAT_FLAG) (2)
154-172 F19.16 mag Hmag GPIPS Mimir H magnitude (H_MAG)
174-194 E21.16 mag e_Hmag GPIPS Mimir H magnitude error (SHMAG)
196-215 F20.18 --- sPhot GPIPS external H-band magnitude uncertainty
(see Clemens et al. 2012ApJS..200...21C 2012ApJS..200...21C)
(SPHOT)
217 I1 --- Hvar [0/1] Variability flag for overlapping FOVs
(see text) (H_VAR)
219-240 F22.18 % Pol ?=99.99 GPIPS debiased polarisation
percentage (P)
242-262 F21.18 % e_Pol ?=99.99 GPIPS debiased polarisation
percentage error (SP)
264-284 E21.18 deg EPA ?=99.99 GPIPS polarisation position angle
(EPA) E of N (PA_DEG)
286-306 E21.18 deg GPA ?=99.99 GPIPS Galactic polarisation position
angle (GPA) (+GLON from +GLAT) (GPA_DEG)
308-328 F21.17 deg e_PA ?=99.99 GPIPS polarisation position angles
error (SPA)
330-351 E22.18 % Q ?=99.99 GPIPS Q Stokes parameter normalized
by Stokes I (Q)
353-373 F21.18 % e_Q ?=99.99 GPIPS Q Stokes parameter error (SQ)
375-396 E22.18 % U ?=99.99 GPIPS U Stokes parameter normalized
by Stokes I (U)
398-418 F21.18 % e_U ?=99.99 GPIPS U Stokes parameter error (SU)
420-421 I2 --- nHWP Number of HWP images in which the star
appears (NHWP)
423-425 I3 --- UF [1/99]?=-99 Usage Flag (UF) (1)
427-454 A28 --- GaiaDR2 Gaiai DR2 designation,
GAIADR2NNNNNNNNNNNNNNNNNNN (DESIG_GAIA)
456-473 A18 --- 2MASS 2MASS designation, JHHMMSSss+DDMMSS or none
(DESIG_2MASS)
475-491 A17 --- GLIMPSE GLIMPSE designation, GLLL.llll+BB.bbbb
(DESIG_GLIMPSE)
493-511 A19 --- WISE WISE designation (DESIG_WISE)
513-519 E7.1 mas Plx ?=99.99 Gaia DR2 parallax (PAR)
521-527 F7.4 mas e_Plx ?=99.99 Gaia DR2 parallax error (PARERR)
529-535 F7.4 mag Gmag ?=99.99 Gaia DR2 G magnitude (GMAG)
537-542 E6.2 mag e_Gmag ?=99.99 Gaia DR2 G magnitude error (GMAGERR)
544-551 F8.3 mas/yr pmRA ?=99.99 Gaia DR2 proper motion along RA,
pmRA*cosDE (PMRA)
553-558 F6.3 mas/yr e_pmRA ?=99.99 Gaia DR2 proper motion along RA
error (PMRAERR)
560-567 F8.3 mas/yr pmDE ?=99.99 Gaia DR2 proper motion along DE
(PMDEC)
569-574 F6.3 mas/yr e_pmDE ?=99.99 Gaia DR2 proper motion along DE
error (PMDECERR)
576-581 F6.3 mag J2mag ?=99.99 2MASS J magnitude (J_2MASS)
583-588 F6.3 mag e_J2mag ?=99.99 2MASS J magnitude error (SJ2MASS)
590-595 F6.3 mag H2mag ?=99.99 2MASS H magnitude (H_2MASS)
597-602 F6.3 mag e_H2mag ?=99.99 2MASS H magnitude error (SH2MASS)
604-609 F6.3 mag Ks2mag ?=99.99 2MASS Ks magnitude (K_2MASS)
611-616 F6.3 mag e_Ks2mag ?=99.99 2MASS Ks magnitude error (SK2MASS)
618-623 F6.3 mag 3.6mag ?=99.99 GLIMPSE IRAC 3.6um magnitude (B36MAG)
625-630 F6.3 mag e_3.6mag ?=99.99 GLIMPSE IRAC 3.6um magnitude
error (E_B36MAG)
632-637 F6.3 mag 4.5mag ?=99.99 GLIMPSE IRAC 4.5um magnitude (B45MAG)
639-644 F6.3 mag e_4.5mag ?=99.99 GLIMPSE IRAC 4.5um magnitude
error (E_B45MAG)
646-651 F6.3 mag 5.8mag ?=99.99 GLIMPSE IRAC 5.8um magnitude (B58MAG)
653-658 F6.3 mag e_5.8mag ?=99.99 GLIMPSE IRAC 5.8um magnitude
error (E_B58MAG)
660-665 F6.3 mag 8.0mag ?=99.99 GLIMPSE IRAC 8.0um magnitude (B80MAG)
667-671 F5.2 mag e_8.0mag ?=99.99 GLIMPSE IRAC 8.0um magnitude
error (E_B80MAG)
673-678 F6.3 mag W1mag ?=99.99 WISE W1 magnitude (W1MAG)
680-685 F6.3 mag e_W1mag ?=99.99 WISE W1 magnitude error (E_W1MAG)
687-692 F6.3 mag W2mag ?=99.99 WISE W2 magnitude (W2MAG)
694-699 F6.3 mag e_W2mag ?=99.99 WISE W2 magnitude error (E_W2MAG)
701-706 F6.3 mag W3mag ?=99.99 WISE W3 magnitude (W3MAG)
708-713 F6.3 mag e_W3mag ?=99.99 WISE W3 magnitude error (E_W3MAG)
715-720 F6.3 mag W4mag ?=99.99 WISE W4 magnitude (W4MAG)
722-727 F6.3 mag e_W4mag ?=99.99 WISE W4 magnitude error (E_W4MAG)
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Note (1): For stars in several FOV, ID1 ID2 ID3 ID4, else ID1 -1 -1 -1.
Note (2): Array of 5 archive catalog match codes as follows:
1 = a POLCAT star matched, if = 1 (0 otherwise)
31 = a Gaia DR2 star matched, see Table B3 for code meaning
7 = a 2MASS star matched, see Table B3 for code meaning
15 = a GLIMPSE star matched, see Table B3 for code meaning
31 = a WISE star matched, see Table B3 for code meaning
Table B3: CAT_FLAG Entry Encoding
-------------------------------------------------------
Entry Additive
Number Score Description
-------------------------------------------------------
(1) (2) (3)
-------------------------------------------------------
1 1 GPIPS POLCAT star was matched
2 1 Gaia DR2 star was matched
2 E_PAR not upper limit (90.0)
4 E_GMAG not upper limit (99.99)
8 E_PMRA not upper limit (90.0)
16 E_PMDEC not upper limit (90.0)
3 1 2MASS PSC star was matched
2 E_J2MASS not upper limit (99.99)
4 E_H2MASS not upper limit (99.99)
8 E_K2MASS not upper limit (99.99)
4 1 GLIMPSE star was matched
2 E_B36MAG not upper limit (99.99)
4 E_B45MAG not upper limit (99.99)
8 E_B58MAG not upper limit (99.99)
16 E_B80MAG not upper limit (99.99)
5 1 WISE star was matched
2 E_W1MAG not upper limit (99.99)
4 E_W2MAG not upper limit (99.99)
8 E_W3MAG not upper limit (99.99)
16 E_W4MAG not upper limit (99.99)
-------------------------------------------------------
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Byte-by-byte Description of file (;): phot/*
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq GPIPS sequential number within the Field
7- 31 A25 --- GPIPS GPIPS designation, GPIPS_JHHMMSS.ss+DDMMSS.s
33- 39 F7.2 pix Ximg GPIPS star center X-location in fits image
41- 47 F7.2 pix Yimg GPIPS star center Y-location in fits image
49- 52 I4 pix Xdet GPIPS mean X-location on detector
54- 57 I4 pix Ydet GPIPS mean Y-location on detector
59- 68 F10.6 deg RAdeg GPIPS right ascension (J2000)
71- 80 F10.6 deg DEdeg GPIPS declination (J2000)
83- 89 F7.4 mag Hmag GPIPS Mimir H magnitude
93- 98 F6.4 mag e_Hmag GPIPS Mimir H magnitude error
102-107 F6.4 --- sPhot GPIPS external H-band magnitude uncertainty
(see Clemens et al. 2012ApJS..200...21C 2012ApJS..200...21C)
110-116 F7.1 ct Sky GPIPS local sky value around this star
118-122 I5 --- Grp GPIPS DAOPHOT group number containing this star
124-128 I5 --- 2ID 2MASS star number in field
131-148 A18 --- 2MASS 2MASS name, JHHMMSSss+DDMMSSsA or 2none_
150-159 F10.6 deg RA2deg ?=0 2MASS right ascension (J2000)
162-171 F10.6 deg DE2deg ?=0 2MASS declination (J2000)
174-179 F6.3 mag J2mag ?=99.990 2MASS J magnitude
182-187 F6.3 mag e_J2mag ?=99.990 2MASS J magnitude error
190-195 F6.3 mag H2mag ?=99.990 2MASS H magnitude
198-203 F6.3 mag e_H2mag ?=99.990 2MASS H magnitude error
206-211 F6.3 mag K2mag ?=99.990 2MASS K magnitude
214-219 F6.3 mag e_K2mag ?=99.990 2MASS K magnitude error
223-228 F6.3 mag 3.6mag ?=99.990 GLIMPSE IRAC 3.6um magnitude
231-236 F6.3 mag e_3.6mag ?=99.990 GLIMPSE IRAC 3.6um magnitude error
239-244 F6.3 mag 4.5mag ?=99.990 GLIMPSE IRAC 4.5um magnitude
247-252 F6.3 mag e_4.5mag ?=99.990 GLIMPSE IRAC 4.5um magnitude error
255-260 F6.3 mag 5.8mag ?=99.990 GLIMPSE IRAC 5.8um magnitude
263-268 F6.3 mag e_5.8mag ?=99.990 GLIMPSE IRAC 5.8um magnitude error
271-276 F6.3 mag 8.0mag ?=99.990 GLIMPSE IRAC 8.0um magnitude
279-284 F6.3 mag e_8.0mag ?=99.990 GLIMPSE IRAC 8.0um magnitude error
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Byte-by-byte Description of file (;): pol/*
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- No GPIPS POLCAT ID number for this star
within the Field
7- 11 I5 --- Seq GPIPS sequential number within the Field
13- 37 A25 --- GPIPS GPIPS designation, GPIPS_JHHMMSS.ss+DDMMSS.s
39- 45 F7.2 pix Ximg GPIPS star center X-location in fits image
47- 53 F7.2 pix Yimg GPIPS star center Y-location in fits image
55- 58 I4 pix Xdet GPIPS mean X-location on detector
60- 63 I4 pix Ydet GPIPS mean X-location on detector
65- 74 F10.6 deg RAdeg GPIPS right ascension (J2000)
77- 86 F10.6 deg DEdeg GPIPS declination (J2000)
89- 95 F7.4 mag Hmag GPIPS Mimir H magnitude
99-104 F6.4 mag e_Hmag GPIPS Mimir H magnitude error
108-113 F6.4 --- sPhot GPIPS external H-band magnitude uncertainty
(see Clemens et al., 2012ApJS..200...21C 2012ApJS..200...21C)
116-122 F7.1 ct Sky GPIPS local sky value around this star
125-130 F6.3 % Pol GPIPS debiased polarisation percentage
133-138 F6.3 % e_Pol GPIPS debiased polarisation percentage error
140-146 F7.3 deg EPA GPIPS polarisation position angle (EPA) E of N
148-154 F7.3 deg GPA GPIPS Galactic polarisation position angle
(GPA) (+GLON from +GLAT)
156-162 F7.3 deg e_PA GPIPS polarisation position angles error
164-170 F7.3 % Q GPIPS Q Stokes parameter normalized by Stokes I
173-178 F6.3 % e_Q GPIPS Q Stokes parameter error
180-186 F7.3 % U GPIPS U Stokes parameter normalized by Stokes I
189-194 F6.3 % e_U GPIPS U Stokes parameter error
196-197 I2 --- nHWP Number of HWP images in which the star appears
199-200 I2 --- UF [1/3]?=-99 Usage Flag (1)
202-206 I5 --- 2ID 2MASS star number in field
209-226 A18 --- 2MASS 2MASS name, JHHMMSSss+DDMMSSsA or 2none_
228-237 F10.6 deg RA2deg ?=0 2MASS right ascension (J2000)
240-249 F10.6 deg DE2deg ?=0 2MASS declination (J2000)
252-257 F6.3 mag J2mag ?=99.990 2MASS J magnitude
260-265 F6.3 mag e_J2mag ?=99.990 2MASS J magnitude error
268-273 F6.3 mag H2mag ?=99.990 2MASS H magnitude
276-281 F6.3 mag e_H2mag ?=99.990 2MASS H magnitude error
284-289 F6.3 mag Ks2mag ?=99.990 2MASS Ks magnitude
292-297 F6.3 mag e_Ks2mag ?=99.990 2MASS Ks magnitude error
301-306 F6.3 mag 3.6mag ?=99.990 GLIMPSE IRAC 3.6um magnitude
309-314 F6.3 mag e_3.6mag ?=99.990 GLIMPSE IRAC 3.6um magnitude error
317-322 F6.3 mag 4.5mag ?=99.990 GLIMPSE IRAC 4.5um magnitude
325-330 F6.3 mag e_4.5mag ?=99.990 GLIMPSE IRAC 4.5um magnitude error
333-338 F6.3 mag 5.8mag ?=99.990 GLIMPSE IRAC 5.8um magnitude
341-346 F6.3 mag e_5.8mag ?=99.990 GLIMPSE IRAC 5.8um magnitude error
349-354 F6.3 mag 8.0mag ?=99.990 GLIMPSE IRAC 8.0um magnitude
357-362 F6.3 mag e_8.0mag ?=99.990 GLIMPSE IRAC 8.0um magnitude error
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Note (1): Usage Flag (from Clemens et al., 2012ApJS..200...21C 2012ApJS..200...21C) as follows:
-4 = zone is bounded by stars showing σP (uncertainty in the linear
polarization percentage) of 2% and mH of 12.5mag
-3 = zone which goes out to σP (uncertainty in the linear
polarization percentage) of 10% and mH of 14mag
-2 = including stars with σP (uncertainty in the linear
polarization percentage) values as high as 100%
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History:
From electronic version of the journal and
https://sites.bu.edu/gpips/fov-based-dr4-data-products
Acknowledgements:
Dan Clemens, clemens(at)bu.edu
References:
Clemens et al., Paper I 2012ApJS..200...19C 2012ApJS..200...19C
Clemens et al., Paper II 2012ApJS..200...20C 2012ApJS..200...20C
Clemens et al., Paper III 2012ApJS..200...21C 2012ApJS..200...21C
(End) Patricia Vannier [CDS] 11-Sep-2020