Spring 1999
Nearby Supernova Campaign
Coordination Center
All materials on this and other /nearsearch pages are copyrighted.
Use of quantitative information from these pages is strictly forbidden
without explicit permission. Qualitative information should be cited as
"Aldering et al., LBL Nearby Supernova Campaign Webpage
(http://panisse.lbl.gov/nearsearch/)."
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Results - Discovery and/or Confirmation of Nearby SNe:
IAUC 7109 (SN1999ab)
IAUC 7117 (SN1999ae, SN1999af, SN1999ag, SN1999ah, SN1999ak, SN1999al)
IAUC 7122 (SN1999am)
IAUC 7125 (SN1999ap, SN1999aq, SN 1999ar)
IAUC 7128 (SN1999as, SN1999at)
IAUC 7130 (SN1999au, SN1999av, SN1999aw, SN1999ax, SN1999ay)
IAUC 7131 (SN1999az, SN1999ba, SN1999bb)
IAUC 7133 (SN1999bc, SN1999bd)
IAUC 7134 (SN1999be, SN1999bf)
IAUC 7136 (SN1999bi, SN1999bj, SN1999bk, SN1999bl, SN1999bm, SN1999bn, SN1999bo, SN1999bp, SN1999bq)
IAUC 7138 (SN1999bh)
Mission Statement:
Several supernova search and asteroid search groups have formed an alliance to
find a large batch of nearby supernova during the Spring of 1999. Participating
search groups include:
Each of these groups have their own scientific interests and needs, and
are securing the follow-up resources required to satisfy them. The key
element of the alliance is that by running all of the supernova searches
simultaneously these follow-up resources will be used in a concentrated and
complementary fashion to supplement the follow-up plans of each of
these groups in order to have the well sampled photometric and
spectroscopic follow-up required to obtain the greatest scientific
return. Those groups that wish to can execute their programs with as
much independence as they desire, but we expect rich collaborations
between groups to develop naturally as the campaign progresses.
For a brief summary of each of the supernova searches, click
here .
Basic Data:
The basic data which is integral to this campaign includes:
- Images to serve as pre-explosion references.
- Subsequent images to be compared with the references to find supernovae.
For the majority of the SNe it is expected that the search criteria
be well defined and accurately quantified.
- Optical (UBVRI) photometry (from CCD imaging) every few days over the
60-day period that the SNe brighten and then fade. Accurate correction
for any non-standard bandpass properties will be critical for obtaining
accurate colors as the supernovae age.
- Optical spectroscopy one per week as the supernovae brighten and then fade. Emphasis will be placed on coverage of blue wavelengths (down to
the atmospheric cut-off) and in obtaining accurate relative fluxes.
Science Goals:
With the above basic data we hope to accomplish the following science goals:
- secure the low-z portion of our SNe~Ia Hubble diagram - which
serves as the calibration for high-z cosmological measurements -
using this large, less biased, sample of nearby SNe~Ia.
- obtain UBVRI lightcurves beginning well before maximum - data
currently available for only a handful of nearby SNe~Ia, and needed to
fit the lightcurves of high-z SNe~Ia for which there is now extensive
data prior to maximum.
- test and refine the lightcurve width vs. brightness relation used
to standardize SNe~Ia luminosities, (to ~0.1 mag after extinction
correction), for which a wide range of lightcurve widths is essential.
- construct a U-band template lightcurve and a U-band lightcurve
width vs. brightness relation to allow U and U-B lightcurves to be used
to correct z > 0.75 SNe~Ia observed with, e.g., HST.
- obtain spectral coverage with lightcurve phase, and thereby
determine accurate K-corrections as a function of lightcurve width and
time.
- determine intrinsic (unreddened) SNe Ia color-curves needed to
establish the correct color zeropoints for host galaxy extinction
corrections.
- test for the existence abnormal host-galaxy extinction laws.
The resulting dataset will also allow detailed exploration of SNe~Ia
properties never before possible, which will almost certainly lead to a
better understanding of SN physics, and may also result in means of
standardizing SNe~Ia in ways not previously envisioned. It will enable
us to determine:
- the intrinsic luminosity function of SNe~Ia.
- new relations between lightcurve shapes, spectral diagnostics
(such as UV continuum slope, Si5180/Si6150 line ratios), etc., and
luminosity.
- SNe properties in different host galaxy environments (as a
surrogate for progenitor age, mass, and metallicity).
- the rates of SNe of all types (presently uncertain by at least
2x for nearby galaxies), including rates as a function of host galaxy
properties.
We have developed tools to help with scheduling and planning of observations.
These include:
- a calender of search and follow-up observations, with detailed information
(when available) for each run, LinCal
- a listing of supernova and their follow-up status, WhatsUp
- links to observatory calenders with nearby search follow-up time here
- spectrophotometric standard stars info here (from ESO) or
here (from APO)
- links to weather information
here
Search Regions:
- EROS:
- 10h < RA < 14h, -12 < Dec < -6; a plot of the field centers is here.
- QUEST:
- 8h < RA < 15h, -1.3 < Dec < 1.3 (not yet firm)
- MOSAIC:
- RA ranges in both northern and southern caps, 0 < Dec < -10
- SpaceWatch:
- Feb fields are listed here.
- El Roble:
- unknown at this time
I hope to have a plot of these regions on-line once the field locations
become firm.
Documents:
The following documents are available:
A descriptive narrative of
data reduction
tasks , presented to the SCP at the May 1999 collaboration meeting.
A first cut at describing the
responsibilities
for the major papers , presented to the SCP at the May 1999 collaboration
meeting.
An initial document describing the
plan for
data reduction , as discussed at the June 2000 SCP collaboration meeting.
An IRAF CL script,
erase_restore.cl, to restore the eraseline to Lick CCD observations.
Postage stamps of YALO images taken in Stromgren U, Johnson B,
Johnson V, Wide R, and Kron-Cousins I, showing the
strong background gradient, with images sorted by time and by sky
brightness:
U-band; sorted by sky brightness &
U-band; sorted by date
B-band; sorted by sky brightness &
B-band; sorted by date
V-band; sorted by sky brightness &
V-band; sorted by date
R-band; sorted by sky brightness &
R-band; sorted by date
I-band; sorted by sky brightness &
I-band; sorted by date
The scale is set so that each image spans +/- 10% around the median sky
brightness. Thus, one can see that sky gradients of more than 20% exist
across many images. Also note that the gradient is often along the
columns of the CCD, pointing to a problem with the characterisation of
the CCD leading to improper data reduction and ruling out moonlight or
other natural sources which might induce a gradient. The problem seems
more frequent when the sky is faint, suggesting problems with
charge-transfer inefficiency or incorrect bias subtraction.
Type Ia Supernovae & Cosmic Acceleration, Aldering, G. (2000), AIP
Conference Proceeding: Cosmic Explosions, ed. S. S. Holt & W. W. Zhang,
Woodbury, New York: American Institute of Physics.
A first draft of Nicolas Regnault's thesis. NOT FOR OUTSIDE DISTRIBUTION!
English language summary of first draft of Nicolas Regnault's thesis.
NOT FOR OUTSIDE DISTRIBUTION!
Maria Cruz conference proceedings paper
Contacts:
Greg Aldering
(email)
is coordinating the searching and follow-up for the Supernova Cosmology Project,
Chris Smith
(email)
is coordinating the searching and follow-up for the MOSAIC/CTIO Team,
Brad Schaefer (email)
is running the QUEST supernova search and follow-up, and
Jim Rich (email)
is running the EROS search.
Greg Aldering (email) is
the author of this web page and most of its associated content. Please contact
him for more information or with updated information. Robert Quimby (email) is the author of
LinCal and WhatsUp and should be contacted if problems arise in the
functioning of these tools. Greg Aldering should be contacted
concerning the content of these tools (e.g., dates on the schedule).
Warning: These pages present on-going scientific research and this
material is not intended for inclusion in publications or proposals,
scientific or otherwise, without explicite prior approval from the
undersigned.
This is a first version of this home page. Please let me
know if there are problems with it. I am reachable at:
Greg Aldering
Lawrence Berkeley Laboratory 50-232
University of California
Berkeley, CA 94720
Phone: (510) 495-2203
Fax: (510) 486-5401
Internet: galdering@lbl.gov
Greg Aldering (galdering@lbl.gov)
last updated Apr 26, 1999