J/ApJ/886/152 ZTF early observations of Type Ia SNe. I. LCs (Yao+, 2019)
ZTF early observations of Type Ia supernovae.
I. Properties of the 2018 sample.
Yao Y., Miller A.A., Kulkarni S.R., Bulla M., Masci F.J., Goldstein D.A.,
Goobar A., Nugent P., Dugas A., Blagorodnova N., Neill J.D., Rigault M.,
Sollerman J., Nordin J., Bellm E.C., Cenko S.B., De K., Dhawan S.,
Feindt U., Fremling C., Gatkine P., Graham M.J., Graham M.L., Ho A.Y.Q.,
Hung T., Kasliwal M.M., Kupfer T., Laher R.R., Perley D.A., Rusholme B.,
Shupe D.L., Soumagnac M.T., Taggart K., Walters R., Yan L.
<Astrophys. J., 886, 152 (2019)>
=2019ApJ...886..152Y 2019ApJ...886..152Y
ADC_Keywords: Supernovae; Photometry; Optical; Extinction
Keywords: Type Ia supernovae ; Sky surveys ; Catalogs ; Supernovae ; Surveys ;
Photometry
Abstract:
Early-time observations of Type Ia supernovae (SNe Ia) are essential
to constrain the properties of their progenitors. In this paper, we
present high-quality light curves of 127 SNe Ia discovered by the
Zwicky Transient Facility (ZTF) in 2018. We describe our method to
perform forced point-spread function photometry, which can be applied
to other types of extragalactic transients. With a planned cadence of
six observations per night (three g + three r), all of the 127 SNe Ia
are detected in both g and r bands more than 10 days (in the rest
frame) prior to the epoch of g-band maximum light. The redshifts of
these objects range from z=0.0181 to 0.165; the median redshift is
0.074. Among the 127 SNe, 50 are detected at least 14 days prior to
maximum light (in the rest frame), with a subset of nine objects being
detected more than 17 days before g-band peak. This is the largest
sample of young SNe Ia collected to date; it can be used to study the
shape and color evolution of the rising light curves in unprecedented
detail. We discuss six peculiar events in this sample: one 02cx-like
event ZTF18abclfee (SN2018crl), one Ia-CSM SN ZTF18aaykjei
(SN2018cxk), and four objects with possible super-Chandrasekhar mass
progenitors: ZTF18abhpgje (SN2018eul), ZTF18abdpvnd (SN2018dvf),
ZTF18aawpcel (SN2018cir), and ZTF18abddmrf (SN2018dsx).
Description:
With the Zwicky Transient Facility (ZTF), we are undertaking a
high-cadence survey with six epochs per night (three g + three r).
This experiment is conducted over a large area of the sky (∼2500deg2)
and thus enables large-number statistics. In this study, we focus on a
special subset of SNe Ia that were discovered more than 10 days prior
to maximum light. Our large (127 objects), homogeneous sample of young
SNe Ia was constructed within the first year of operations by ZTF
in 2018.
The ZTF camera is mounted on the 48 inch Samuel Oschin Telescope (P48)
at Palomar Observatory. ZTF divides its observing time between public
surveys (40%), partnership surveys (40%), and Caltech surveys (20%).
Bellm+ (2019PASP..131f8003B 2019PASP..131f8003B) provide details of the ZTF surveys.
A large fraction of our spectroscopic follow-up observations were
conducted by the Spectral Energy Distribution Machine (SEDM) on the
robotic Palomar 60 inch telescope (P60). Other follow-up instruments
include the Double Spectrograph (DBSP) on the Palomar 200 inch
telescope (P200), the Low-Resolution Imaging Spectrometer (LRIS) on
the Keck I 10m telescope, the Andalucia Faint Object Spectrograph and
Camera (ALFOSC) on the 2.56m Nordic Optical Telescope (NOT), the Dual
Imaging Spectrograph (DIS) on the Astrophysical Research Consortium
(ARC) 3.5m telescope at Apache Point Observatory (APO), the
SPectrograph for the Rapid Acquisition of Transients (SPRAT) on the
2.0m Liverpool Telescope (LT), and the Deveny spectrograph on the 4.3m
Discovery Channel Telescope (DCT); observations collected between 2018
May and October.
Within our sample, 95 objects have one spectrum; 22 have two, five
have three, one has four, two have five, and one has 10.
See Section 4.2.1.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
sample.dat 176 127 General information and photometric properties
of 127 SNe Ia (Tables 2 and 3)
table5.dat 94 94186 P48 photometry of 127 SNe Ia
table5.fits 2880 3797 Table 5 in original FITS format
--------------------------------------------------------------------------------
See also:
B/sn : Asiago Supernova Catalogue (Barbon et al., 1999-)
J/AJ/137/3731 : ESSENCE high-redshift supernova (Foley+, 2009)
J/ApJ/700/331 : Light curves of type Ia supernovae (CfA3) (Hicken+, 2009)
J/ApJ/716/712 : HST light curves of six SNe and Union2 (Amanullah+, 2010)
J/AJ/139/519 : Carnegie supernova project. SNe Ia (Contreras+, 2010)
J/ApJS/190/418 : Light curves for 165 SNe (Ganeshalingam+, 2010)
J/A+A/526/A28 : SDSS-II supernovae NTT and NOT spectroscopy (Oestman+, 2011)
J/AJ/142/156 : The CSP (DR2): photometry of SNe Ia (Stritzinger+, 2011)
J/AJ/143/126 : Spectroscopy of 462 nearby Type Ia SNe (Blondin+, 2012)
J/ApJS/200/12 : CfA4: light curves for 94 type Ia SNe (Hicken+, 2012)
J/MNRAS/425/1789 : Berkeley supernova Ia program. I. (Silverman+, 2012)
J/A+A/568/A22 : Joint analysis of the SDSS-II & SNLS SNe Ia (Betoule+, 2014)
J/MNRAS/446/3895 : The rising light curves of Type Ia supernovae (Firth+, 2015)
J/ApJ/826/56 : HST/WFC3 obs. of Cepheids in SN Ia host gal. (Riess+, 2016)
J/AJ/154/211 : The CSP (DR3): photometry of low-z SNIa (Krisciunas+, 2017)
J/ApJ/870/L1 : K2 obs. of type Ia supernova SN 2018oh (Dimitriadis+, 2019)
J/ApJ/870/13 : K2 LC alternative analysis of ASASSN-18bt (Shappee+, 2019)
http://www.wis-tns.org/ : Transient Name Server (TNS) home page
Byte-by-byte Description of file: sample.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- ZTF ZTF Name
14- 24 F11.7 deg RAdeg [12.52/348.53] Right Ascension (J2000)
26- 35 F10.7 deg DEdeg [21.38/79.06] Declination (J2000)
37- 45 A9 --- Name SN IAU name from the Transient Name
Server (TNS)
47- 58 A12 --- TNS TNS Internal Name, indicating the discovery
group
60- 79 A20 --- Tel Followup telescope(s) (1)
81-104 A24 --- Phase Spectroscopic phase(s) at followup (1)
106-114 A9 --- Subtype Ia Subtype ("SC"=super-Chandrasekhar)
115 A1 --- u_Subtype [*] Uncertainty flag on Ia Subtype (2)
117-122 F6.4 --- z [0.018/0.17] Host galaxy redshift
123 A1 --- n_z Note on z (3)
125-130 F6.4 mag E(B-V) [0.006/0.12] Forground Galactic extinction
from Schlafly & Finkbeiner
(2011ApJ...737..103S 2011ApJ...737..103S)
132-139 F8.2 d tgmax [58243.79/58396.52] Epoch of g-band maximum
light, Modified Julian Date (4)
141-144 F4.2 d e_tgmax [0/1.5] Uncertainty in tgmax
146-149 F4.2 mag Delm15g [0.4/1.7]? Decline within 15d from maximum
in g band (4)
151-154 F4.2 mag e_Delm15g [0/0.1]? Uncertainty in Delm15g
156-160 F5.2 --- x1 [-2.6/4.2] Light curve shape parameter, x1,
from SALT2 fitting (salt2x1)
162-165 F4.2 --- e_x1 [0/1.1] Uncertainty in x1
167-171 F5.2 --- c [-0.2/0.7] Light curve color, c, from SALT2
fitting (salt2c)
173-176 F4.2 --- e_c [0/0.2] Uncertainty in c
--------------------------------------------------------------------------------
Note (1): Follow-up telescope and epoch of the spectrum with respect to tgmax
used to determine the spectral subtype. If multiple observations were used
then the values are given as a comma delimited string.
Note (2):
* = Classification can not be reliably determined from spectroscopy alone.
See Section 4.2 for details.
Note (3): Flag as follows:
h = The host galaxy redshift (z) is shown with 4 decimals if:
* z is taken from NED,
* z is measured from the galaxy spectrum obtained by us
(SEDM spectra will be described in detail by M. Rigault+ 2019,
in preparation),
* z is measured from a SN spectrum where the host Hα line
can be identified.
f = Redshifts inferred from the Supernova Identification tool (SNID;
Blondin & Tonry 2007ApJ...666.1024B 2007ApJ...666.1024B) fit on SN spectra
(3 significant decimals).
See Section 4.2.2.
a = Redshift of ZTF18abptsco was reported by Gomez+ 2018ATel12052....1G 2018ATel12052....1G
(2 significant decimals).
Note (4): Values of tgmax and deltam15g for peculiar events (classified as
"02cx-like", "Ia-CSM", "SC" or "SC*") were obtained from polynomial
fits to the g-band light curve. For other objects, both tgmax and
deltam15g were from SALT2 estimates. If a target does not have any
g-band observations in the time range [tgmax+10, tgmax+20] deltam15g
cannot be securely estimated and is thus shown in blank
(e.g., ZTF18abuqugw).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- ZTF ZTF name of the supernova
14- 25 F12.4 d JD Julian Date
27 I1 --- PID [1/3] Program identifier (programid) (1)
29- 32 I4 --- Field [584/1824] ZTF field identifier (fieldid) (2)
34- 35 I2 --- CCD [1/16] CCD identifier (from 1 to 16) (ccdid) (2)
37 I1 --- qID [1/4] Quadrant (CCD-amplifier) identifier
(from 1 to 4) (2)
39 I1 --- Filt [1/2] Filter identifier (1=gZTF, 2=rZTF)
(filterid) (2)
41- 45 F5.3 arcsec Seeing [1.19/4] Photometric seeing (FWHM) at the
Palomar Observatory at the time of observation
47- 55 F9.6 mag ZP [22.63/28.64] Photometric zero-point
57- 65 E9.4 mag e_ZP [5.3e-7/0.018] ZP uncertainty (zp_unc)
67- 73 F7.1 --- Flux [-3728/19044] Forced PSF-fit flux for the
difference image (DN units) (fmcmc) (3)
75- 79 F5.1 --- e_Flux [11/710] Flux uncertainty (fmcmc_unc)
81- 86 F6.1 --- C [-999/200.3] History offset in the baseline
region (DN units) (4)
88- 94 F7.2 --- Chi2 [-999/3.3] Square root of the reduced
chi-square statistics (chi2_nu) (4)
--------------------------------------------------------------------------------
Note (1): Program identifier as follows:
1 = public survey,
2 = partnership survey,
3 = Caltech survey
Note (2): Observations for each target could be covered by multiple fields.
To ensure that the reference images do not contain contamination from
SN flux, we need to treat each field (with specific CCD-quadrant
therein) for a given filter separately. Hereafter we use "fcqf ID".
The fcqf ID (Equation (1)) can be calculated with Columns Field, CCD,
qID and Filt:
fcqfID=(FieldID)x10000+(CCDID)x100+(QuadrantID)x10+(Filter_ID)
Note (3): Note that this is the direct measurement from Section 3.3.
Baseline correction described in Section 3.5 is not applied to these values.
Note (4): Note that Columns C and Chi2 are set to -999 if baseline region
(Nbase)<30. See Section 3.5 for details.
--------------------------------------------------------------------------------
Acknowledgements:
Yuhan Yao [ yyao at astro.caltech.edu ]
History:
From electronic version of the journal
12-May-2021: Insert into VizieR
10-Jun-2021: sample.dat updated (corrections made by the author in ApJ)
References:
Yao et al. Paper I. 2019ApJ...886..152Y 2019ApJ...886..152Y This catalog
Miller et al. Paper II. 2020ApJ...902...47M 2020ApJ...902...47M Cat. J/ApJ/902/47
Bulla et al. Paper III. 2020ApJ...902...48B 2020ApJ...902...48B Cat. J/ApJS/902/48
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 20-Apr-2021