J/AJ/141/205 UVOT imaging of M81 and Holmberg IX (Hoversten+, 2011)
Swift Ultraviolet/Optical telescope imaging of star-forming regions in M81 and
Holmberg IX.
Hoversten E.A., Gronwall C., Vanden Berk D.E., Basu-Zych A.R.,
Breeveld A.A., Brown P.J., Kuin N.P.M., Page M.J., Roming P.W.A.,
Siegel M.H.
<Astron. J., 141, 205 (2011)>
=2011AJ....141..205H 2011AJ....141..205H
ADC_Keywords: Galaxies, photometry ; Ultraviolet ; H II regions
Keywords: galaxies: individual (M81, Holmberg IX) - galaxies: star formation -
H II regions
Abstract:
We present Swift UV/Optical Telescope (UVOT) imaging of the galaxies
M81 and Holmberg IX. We combine UVOT imaging in three near-ultraviolet
(NUV) filters (uvw2: 1928Å; uvm2: 2246Å; uvw1: 2600Å) with
ground-based optical imaging from the Sloan Digital Sky Survey to
constrain the stellar populations of both galaxies. Our analysis
consists of three different methods. First, we use the NUV imaging to
identify UV star-forming knots and then perform spectral energy
distribution (SED) modeling on the UV/optical photometry of these
sources. Second, we measure surface brightness profiles of the disk of
M81 in the NUV and optical. Lastly, we use SED fitting of individual
pixels to map the properties of the two galaxies.
Description:
UVOT observations of M81 and Holmberg IX were made between 2005 April
21 and 2009 September 4.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 91 129 Swift UVOT observations of M81
table3.dat 163 1326 Source photometry and fitted parameters
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See also:
J/ApJ/438/181 : Observations of H II Regions in M81 (Hill+ 1995)
J/ApJ/554/202 : ROSAT X-ray observations of M81 (Immler+, 2001)
J/ApJS/144/213 : Chandra X-ray observations of M81 (Swartz+, 2003)
J/AJ/126/1286 : Halpha+[NII] observations of M81 HII regions (Lin+, 2003)
J/ApJ/648/987 : UV through far-IR analysis of M81 (Perez-Gonzalez+, 2006)
J/other/Ser/179.87 : Halpha in HII regions of Holmberg IX (Arbutina+, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- Name Name of target of observation (1)
18- 28 A11 --- ObsID Swift observation ID number
32- 41 A10 --- Date Date of Swift observation
45- 48 I4 s tuvw2 UVOT exposure time in uvw2 filter
52- 55 I4 s tuvm2 UVOT exposure time in uvm2 filter
59- 62 I4 s tuvw1 UVOT exposure time in uvw1 filter
66- 69 I4 s tu UVOT exposure time in u filter
73- 76 I4 s tb UVOT exposure time in b filter
80- 83 I4 s tv UVOT exposure time in v filter
87- 91 F5.2 arcmin Offset Observation position offset from M81 center
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Note (1): Target name are Automatic Target, HOLMBERGIXX-1, M81,
M81X9 and NGC3031.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Gal Galaxy in which source resides (M81 or HoIX)
7- 14 F8.4 deg RAdeg Right ascension in decimal degrees (J2000)
16- 22 F7.4 deg DEdeg Declination in decimal degrees (J2000)
24- 28 F5.2 mag uvw2 UVOT UVW2 filter AB magnitude (1)
30- 34 F5.2 mag e_uvw2 Random error in uvw2mag (2)
36- 40 F5.2 mag uvm2 UVOT UVM2 filter AB magnitude (1)
42- 46 F5.2 mag e_uvm2 Random error in uvm2mag (2)
48- 52 F5.2 mag uvw1 UVOT UVW1 filter AB magnitude (1)
54- 58 F5.2 mag e_uvw1 Random error in uvw2mag (2)
60- 64 F5.2 mag umag SDSS u filter AB magnitude (1)
66- 70 F5.2 mag e_umag Random error in umag (2)
72- 76 F5.2 mag gmag SDSS g filter AB magnitude (1)
78- 82 F5.2 mag e_gmag Random error in gmag (2)
84- 88 F5.2 mag rmag SDSS r filter AB magnitude (1)
90- 94 F5.2 mag e_rmag Random error in rmag (2)
96-100 F5.2 mag imag SDSS i filter AB magnitude (1)
102-106 F5.2 mag e_imag Random error in imag (2)
108-112 F5.2 mag zmag SDSS z filter AB magnitude (1)
114-118 F5.2 mag e_zmag Random error in zmag (2)
120-124 I5 s tuvw2 UVOT exposure time in uvw2 filter
126-130 I5 s tuvm2 UVOT exposure time in uvm2 filter
132-136 I5 s tuvw1 UVOT exposure time in uvw1 filter
138-141 I4 pix2 Area Isophotal area in square pixels (3)
143-147 F5.2 --- rchi2 Reduced chi square of model fit
149-153 I5 Myr Age Best fitting model age
155-159 F5.2 mag AV Best fitting internal extinction AV
161-163 A3 --- Dust Best fitting dust model (4)
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Note (1): Uncorrected for Milky Way extinction which in each filter is
assumed to be:
uvw2 = 0.65mag; uvm2 = 0.69mag; uvw1 = 0.55mag; u = 0.38mag;
g = 0.29mag; r = 0.21mag; i = 0.16mag; z = 0.12mag.
Note (2): Where the systematic errors in each filter are:
uvw2 = ±0.03; wvm2 = ±0.03; wvw1 = ±0.03; u = ±0.03;
g = ±0.01; r = ±0.01; i = ±0.01; z = ±0.02.
Note (3): Each pixel is a square arcsecond.
Note (4): MW, LMC, SMC, Calzetti, or 0 for AV=0.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 14-Sep-2012