"""
================================================================================
Routines to make a chart of upcoming transit events. The main
function to call is :func:`transitChart`, which has an example in its
documentation. A fully automated chart-maker can be found in :func:`makeCharts`
:REQUIREMENTS:
PyEphem -- http://rhodesmill.org/pyephem/
Numpy -- http://numpy.org/
:doc:`analysis` -- For importing planet-class objects.
:SEE ALSO:
http://var2.astro.cz/EN/tresca/index.php
:TO-DO LIST:
Print uncertainties in ephemeris when they're sufficiently large
2010-10-11 23:06 IJC: Updated with La Palma location.
2010-03-23 09:37 IJC: Written by IJC to duplicate Josh Winn's page @ MIT.
2011-08-09 13:21 IJMC: Copied over :func:`jd2gd` and :func:`gd2jd`.
2011-09-30 11:01 IJMC: Added moon separation.
================================================================================
"""
try:
import analysis as an
except:
pass
import ephem
#from nsdata import jd2gd, gd2jd
from numpy import cos, pi, array, zeros, sqrt, isfinite, argsort
import pdb
AU = 1.49598e13
msun = 1.98892e33
mjup = 1.8987e30
rjup = 7.1492e9
rsun = 6.955e10
hr = 1./24.
planetkeys = ['tt', 'per', 't14', 'ra_string','dec_string']
# Create a 'star' object, then give it the target's RA and DEC
#target = ephem.star('Rigel')
#target._ra, target._dec = p.ra_string,p.dec_string
[docs]def gd2jd(datestr):
""" Convert a string Gregorian date into a Julian date using Pylab.
If no time is given (i.e., only a date), then noon is assumed.
Timezones can be given, but UTC is assumed otherwise.
:EXAMPLES:
::
print gd2jd('Aug 11 2007') #---------------> 2454324.5
print gd2jd('Aug 11 2007, 12:00 PST') #-----> 2454324.29167
print gd2jd('12:00 PM, January 1, 2000') #--> 2451545.0
:REQUIREMENTS: :doc:`matplotlib`
:SEE ALSO: :func:`jd2gd`
"""
# 2008-08-26 14:03 IJC: Created
# 2010-12-08 13:00 IJC: Removed "+ 3442850" from num2julian call
# 2011-05-19 11:37 IJMC: Put the factor back in for error-catching...
import matplotlib.dates as dates
if datestr.__class__==str:
d = dates.datestr2num(datestr)
jd = dates.num2julian(d)
if jd<0:
jd = dates.num2julian(d + 3442850)
print "You are probably using an old version of Matplotlib..."
else:
jd = []
return jd
[docs]def jd2gd(juldat):
""" Convert a numerial Julian date into a Gregorian date using Pylab.
Timezone returned will be UTC.
:EXAMPLES:
::
print jd2gd(2454324.5) #--> 2007-08-12 00:00:00
print jd2gd(2451545) #--> 2000-01-01 12:00:00
:SEE ALSO: :func:`gd2jd`"""
# 2008-08-26 14:03 IJC: Created
# 2011-01-22 16:24 IJC: Removed arbitrary (?) subtraction of 3442850 from 'd'
import matplotlib.dates as dates
d = dates.julian2num(juldat)
gd = dates.num2date(d )
return gd
[docs]def nextTransit(planet, jd=None, dt0=0.0):
"""Return JD of the next transit of a planet after a given JD. If
jd==None, the current date is used."""
# 2010-03-19 11:19 IJC: Created
import datetime
if jd==None:
jd = gd2jd(str(datetime.datetime.today()))
transitNum = int((jd-(planet.tt + dt0))/planet.per)
return (planet.tt + dt0) +planet.per*(transitNum+1)
[docs]def nextEclipse(planet, jd=None, dt0=0.0):
"""Return JD of the next eclipse of a planet after a given JD. If
jd==None, the current date is used.
Note that this only works for planets on circular orbits --
eccentric orbits will be given an incorrect Eclipse time!"""
# 2011-01-22 22:07 IJC: Created
import datetime
if jd==None:
jd = gd2jd(str(datetime.datetime.today()))
transitNum = int((jd - (planet.tt + dt0))/planet.per)
return (planet.tt + dt0) + planet.per*(transitNum + 0.5)
[docs]def getPerimeter(a, ecc):
"""Compute perimeter of an ellipse given its semimajor axis and
eccentricity. This is only accurate to a few percent.
"""
# 2010-03-22 21:37 IJC: Created
b = a*sqrt(1-ecc**2)
p = pi*(3*(a+b)-sqrt((3*a+b)*(a+3*b)))
return p
[docs]def getTransitDuration(p):
"""Compute duration of transit, in days. Units of inputs should be:
Rp -- Jupiter Radii
depth -- (none)
a -- AU
ecc-- (none)
P -- days
inc-- degrees
"""
# 2011-01-22 16:42 IJC: Added error-catching for odd, eccentric
# orbits that aren't properly handled by this algorithm. I should
# probably do it correctly!
peri = getPerimeter(p.a, p.ecc) * AU/rjup
vorb = (peri/p.per)
term1 = (p.r*(1+1./sqrt(p.depth)))**2
term2 = (p.a*cos(p.i*pi/180)*AU/rjup)**2
if term1 > term2:
ret = 2*sqrt(term1 - term2)/vorb
else:
print "%s: CANNOT COMPUTE TRANSIT DURATION!!!" % p.name
ret = 0.0
return ret
[docs]def getTransitTimes(planet, *arg, **kw):
"""
If no arguments passes, get info for the next 10 transits.
If one (Julian) Date entered, print transits until that date.
If two (Julian) Dates entered, print transits between those dates.
If keyword eclipse==True, get the Eclipse times instead.
"""
# 2010-03-19 11:19 IJC: Created
# 2011-01-22 22:08 IJC: Added eclipse keyword option
nextEventFunc = nextTransit
if kw.has_key('eclipse'):
if kw['eclipse'] is True:
nextEventFunc = nextEclipse
dt0 = 0.0
if kw.has_key('dt0'):
dt0 = kw['dt0']
if len(arg)==0:
firstEvent = nextEventFunc(planet, dt0=dt0)
nEvents = 10
elif len(arg)==1:
firstEvent = nextEventFunc(planet,arg[0], dt0=dt0)
lastEvent = nextEventFunc(planet,arg[0], dt0=dt0)
nEvents = int((lastEvent-firstEvent)/planet.per+0.001) # roundoff
else: # len(arg)==2
firstEvent = nextEventFunc(planet,arg[0], dt0=dt0)
lastEvent = nextEventFunc(planet,arg[1], dt0=dt0)
nEvents = int((lastEvent-firstEvent)/planet.per+0.001) # roundoff
return [firstEvent+ii*planet.per for ii in range(nEvents)]
[docs]def getMoonAngle(jd, target, obs):
"""Returns the angle between a target and the moon (in radians).
:INPUTS:
jd : float or 1D numpy array
Julian Dates of times
target : ephem.star
target being observed
obs : ephem.Observer
observatory with latitude, longitude, and elevation set
"""
# 2011-09-30 09:56 IJMC: Created from getAirmassAndSunAlt
if not hasattr(jd, '__iter__'):
jd = [jd]
JDwas1D = True
else:
JDwas1D = False
moon = ephem.Moon()
njd = len(jd)
moonangle = zeros(njd, float)
for ii in range(njd):
t = jd[ii]
obs.date=jd2gd(t)
target.compute(obs)
moon.compute(obs)
moonangle[ii] = ephem.separation(target, moon)
if JDwas1D:
moonangle = moonangle[0]
return moonangle
[docs]def getAirmassAndSunAlt(jd, target, obs) :#, twilight=12, airmax=2.2):
""" Return airmass and sun altitude at a set of times.
INPUTS:
JD -- a sequence of times
target -- an ephem.star-class object
obs -- an ephem.Observer-class object
Objects w/airmass>9.99 (or below the horizon) are set to 9.99
"""
#2010-03-19 11:32 IJC: Created
if not hasattr(jd,'__iter__'):
jd = [jd]
sun = ephem.Sun()
njd = len(jd)
airmass = zeros(njd,float)
sunalt = zeros(njd,float)
for ii in range(njd):
t = jd[ii]
obs.date=jd2gd(t)
target.compute(obs)
sun.compute(obs)
airmass[ii] = 1./cos(pi/2-target.alt)
sunalt[ii] = 180*sun.alt/pi
airmass[(airmass<0) + (airmass > 9.99)] = 9.99
return airmass, sunalt
def printflags(observable):
nobs = len(observable)
flagstring = ''
for ii in range(nobs):
if observable[ii]:
flagstring += str(ii)
else:
flagstring += ' '
return flagstring
def printstats(jd, sunalt, airmass, delim=' '):
day = jd2gd(jd)
ret = 'UT=%02g%02gZZZsun=%5.1fZZZz=%5.2f' %(day.hour,day.minute,sunalt,airmass)
#ret = 'UT=%02g%02g sun=%5.1f z=%5.2f' %(day.hour,day.minute,sunalt,airmass)
ret = ret.replace(' ', '=')
ret = ret.replace('ZZZ', delim)
return ret
def printline(observable, jdCen, jd, sunalt, airmass, delim=' '):
jd = array(jd).ravel()
sunalt= array(sunalt).ravel()
airmass = array(airmass).ravel()
dCen = jd2gd(jdCen)
njd = len(jd)
if njd<>len(sunalt) or njd<>len(airmass):
ret = 'input JD, sunalt, and airmass must have equal lengths\n'
else:
ret = printflags(observable)
ret += '%s%07.6f' % (delim, jdCen)
ret += '%s%i%s%2i%s%2i' % (delim*2, dCen.year,delim, dCen.month,delim, dCen.day)
for ii in range(njd):
ret += '%s%s' % (delim*2, printstats(jd[ii], sunalt[ii], airmass[ii], delim=delim))
return ret
[docs]def isGoodPlanet(planet):
"""Check if planet object has the necessary fields, and that they are
non-empty."""
#2010-03-19 13:39 IJC: Created
# 2011-01-22 16:47 IJC: Updated to check for finite values
isGood = True
for key in planetkeys:
if not hasattr(planet,key):
isGood = False
break
else:
thiskey = eval('planet.%s' % key)
if thiskey.__class__==str:
if len(thiskey)==0:
isGood = False
break
elif not isfinite(thiskey):
isGood = False
#else Do nothing
return isGood
[docs]def transitChart(planets, date1, date2, obs='lick', airmax=2.5, twilight=12, tpad=1, cutoff=3, eclipse=False, delim=' ', chron=False, dt0=0.0):
"""
:INPUTS:
planets : objects with the following fields:
.per (period/days)
.tt (transit ephemeris, JD)
.t14 (transit duration, days)
.ra_string (string; RA of target in hh:mm:ss)
.dec_string (string; Dec of target in dd:mm:ss)
date1, date2 : str
Date strings (e.g., of the form "YYYY-MM-DD") bracketing the
timespan for which transits/eclipses will be calculated.
obs : str
'lick' or 'keck' or 'lapalma' or 'mtgraham' or 'mtbigelow' or
'andersonmesa' or 'kpno' or 'ctio' or 'cerropachon' or
'palomar' or 'cerroparanal' or 'lasilla' or 'calaralto' or
'lascampanas'
airmax : float
Maximum acceptable airmass
twilight : float
Minimum acceptable angular distance of sun below horizon, in
degrees.
tpad : float
Number of hours by which ingress and egress should be padded
cutoff : int
Minimum number of acceptable "observational checkpoints."
Valid values are 0-5, inclusive. A value of "5" will only
show fully visible transits (pre-ingress, ingress,
mid-transit, egress, post-egress), "0" will show ALL transits
(even, e.g., those during daylight), and intermediate values
will show fully visible transits and some number of partial
transits.
eclipse : bool
If True, compute times of eclipses, not of transits. Note
that eclipse times are all computed assuming circular orbits!
delim : str
Character(s) used to delimit the output text table
chron : bool
If True, sort all computed events (for ALL planets
considered) by mid-event time. If False, events will be
listed separately for each planet.
dt0 : float
Number of days by which to shift transit center time: a "fudge
factor." A positive value here means that the output text
table will show events occuring later than the '.tt' field of
the planet object would otherwise indicate. Leave this set to
"zero" unless you have a good reason to do otherwise!
:EXAMPLE:
::
import transittime as tt
class planet: # Simplest valid planet class
def __init__(self):
return
p = planet()
p.per = 1.58040482
p.tt, p.t14 = 2454980.7487955, 0.03661806
p.ra_string, p.dec_string = '17:15:18.94', '04:57:49.70'
p.name = 'GJ 1214 b'
text = tt.transitChart(p, '2013-01-01','2013-12-31')
:EXAMPLE:
::
import analysis as an # requires :doc:`analysis`
import transittime as tt
from numpy import array
planet_names = an.getobj()
all_planets = map(an.getobj, planet_names)
transit_flag = array([p.transit==1 for p in all_planets])
transiters = array(all_planets)[transit_flag]
text = tt.transitChart(transiters, '2013-01-01', '2013-08-01')
:NOTES:
Always check transit predictions with at least two independent tools!
Eclipse times are currently computed assuming circular orbits.
Need to fix this...
"""
# 2010-03-19 11:39 IJC: Created
# 2010-10-11 23:08 IJC: Updated with LaPalma location
# 2011-01-22 22:11 IJC: Added eclipse flag
# 2011-02-08 09:23 IJC: Added delim flag
# 2011-08-23 16:43 IJMC: Set target.name = planet.name
# 2011-08-26 16:41 IJMC: Added 'chron' flag.
# 2011-09-13 20:59 IJMC: Slightly modified planet header text
# 2011-09-20 15:06 IJMC: Added 'mtgraham' observatory location
# 2012-01-25 11:54 IJMC: Added 'cerropachon'
# 2012-04-06 15:50 IJMC: Added 'palomar'
# 2012-08-06 22:14 IJMC: Added cerro paranal and la silla and calar alto
# 2012-09-05 08:52 IJMC: Added las campanas
# 2013-01-15 10:11 IJMC: Added mtbigelow/catalina option, updated DOC text.
if not hasattr(planets,'__iter__'):
planets = [planets]
nplanets = len(planets)
jd1 = gd2jd(date1)
jd2 = gd2jd(date2)
ind = [1,2,3] # [01234] = [pre-, ingress, mid-transit, egress, post-]
obs = str.lower(obs)
observer = setupObservatory(obs)
# Start making the text file lines:
if eclipse:
eventType = 'ECLIPSE'
else:
eventType = 'TRANSIT'
init_header = ["%s listing between %s and %s, for %s observatory\n" % (eventType, date1,date2, obs)]
init_header.append("The numerical string specifies which of the following events are visible:\n")
init_header.append("0: pre-ingress\n1: first contact\n2: mid-%s\n3: fourth contact\n4: post-egress\n" % eventType )
init_header.append("where pre-ingress and post-egress have been padded by %f hours\n\n" % tpad)
init_header.append('Criteria for observability: z<%f and sun_altitude<-%f deg\n\n' % (airmax,twilight))
init_header.append("Clock times below are UT, but HAVE NOT been corrected for heliocentricity\n\n")
init_header.append("Created by Ian Crossfield (but based on Josh Winn of MIT's charts)\n\n")
planetevents = []
eventcenters = []
ret = init_header
for planet in planets:
if not hasattr(planet, 'name'):
planet.name = '(unnamed planet)'
pheader = []
pfooter = []
pheader.append('\n')
pheader.append('%s T0: %4.10f Per: %4.15f\n' %(planet.name,planet.tt + dt0,planet.per))
if dt0<>0:
pheader.append(' (all transit center times have been shifted by %4.10f days)\n' % dt0)
if not isGoodPlanet(planet):
planet.t14 = getTransitDuration(planet)
pheader.append ('(transit duration missing; approximately computed: %3.2f min)\n' %(planet.t14*1440) )
if isGoodPlanet(planet):
pheader.append(' HJD-midtransit UTdate-mid Ingress: Middle: Egress:\n')
# Setup target object:
target = ephem.star('Rigel')
target.name = planet.name
target._ra, target._dec = planet.ra_string,planet.dec_string
target._pmra, target._pmdec = 0.,0.
times = getTransitTimes(planet, jd1,jd2, eclipse=eclipse, dt0=dt0)
ntimes = len(times)
for ii in range(ntimes):
tOffsets = array([-planet.t14/2-hr*tpad, -planet.t14/2, 0., \
+planet.t14/2,+planet.t14/2+hr*tpad])+times[ii]
if not isfinite(tOffsets[0]):
print "some of tOffsets were not finite."
print "tOffsets>>", tOffsets
pdb.set_trace()
moonangle = getMoonAngle(tOffsets, target, observer) * 180./pi
airmass, sunalt = getAirmassAndSunAlt(tOffsets, target, observer)
observable = (sunalt<-twilight) * (airmass>0) * \
(airmass<airmax) #* (moonangle > moonlimit)
if observable.sum()>=cutoff:
thisline = printline(observable, times[ii], tOffsets[ind], sunalt[ind], airmass[ind], delim=delim)
moonsep = '%5.1f' % min(moonangle)
#ret = 'UT=%02g%02g sun=%5.1f z=%5.2f' %(day.hour,day.minute,sunalt,airmass)
moonsep = moonsep.replace(' ', '=')
thisline = thisline + (delim*2) + 'moonSep=' + moonsep + '\n'
pfooter.append(thisline)
#pdb.set_trace()
else:
pheader.append('planet object lacks a necessary field:\n')
checkstr = ''.join(['%s: %s ' %(key,eval("planet.%s"%key)) for \
key in planetkeys])
pfooter.append('Checking for fields: %s\n' % checkstr)
if len(pfooter)>0:
ret = ret + pheader + pfooter
planetevents = planetevents + \
([line.replace('\n', delim+planet.name+'\n') \
for line in pfooter])
if chron:
eventcenters = map(float, [pe[6:20] for pe in planetevents])
chronindex = argsort(eventcenters)
chronret = init_header + list(array(planetevents)[chronindex])
ret = chronret
return ret
#tOffsets = array([tCen-p.t14/2-hr, tCen-p.t14/2, tCen, tCen+p.t14/2,tCen+p.t14/2+hr])
#print obs.date, target.alt, 1./cos(pi/2-target.alt), sun.alt
#
[docs]def makeCharts(path='/Users/ianc/temp/', obs=['lick', 'keck', 'cerropachon'], eclipse=[True, False], \
months=18, clobber=False, kw=None, planet_names=None):
"""Make transit charts for specified observatories for all planets.
:OPTIONS:
path : str
directory in which to write text output
obs : list of str
observatories, acceptable to :func:`transitChart`
eclipse : list of bool
whether to compute eclipses (if True) or transits (if False).
Note that eclipse predictions assume circular orbits!
months : int
Number of (31-day) months from present date for computations
clobber : bool
If true, overwrite file if it already exists. Otherwise, don't.
kw : dict or None
dict of keywords to pass to :func:`transitChart`
planet_names : None or list of planet objects
Planets for which table should be constructed. If "none", do
it for all planets in the database.
:REQUIREMENTS:
:doc:`analysis`, :doc:`datetime`, :doc:`os`
:SEE_ALSO:
:func:`transitChart`
"""
# 2011-11-01 21:12 IJMC: Created to save me some time.
# 2013-01-08 23:23 IJMC: Added planet_names option
import datetime, os
# Check inputs:
if not hasattr(eclipse, '__iter__'):
eclipse = [eclipse]
if not hasattr(obs, '__iter__') or isinstance(obs, str):
obs = [obs]
if not kw.__class__==dict:
print "Input 'kw' must be of type dict; thus 'kw' has not set any keywords."
kw = dict()
elif kw.has_key('chron'):
print "'Chron' key is unnecessary (and ignored). ",
print "Both chronological and non-chronological transit charts will be output."
junk = kw.pop('chron')
# Prepare dates:
startdate = datetime.datetime.today() - datetime.timedelta(days=1)
stopdate = startdate + datetime.timedelta(days=months*31)
startstr = ('%s' % startdate)[0:10]
stopstr = ('%s' % stopdate)[0:10]
# Prepare list of planet objects:
if planet_names is None:
planet_names = an.getobj()
all_planets = map(an.getobj, planet_names)
else:
all_planets = planet_names
transit_flag = array([p.transit==1 for p in all_planets])
transiters = array(all_planets)[transit_flag]
# Loop over all options:
for thisobs in obs:
format_params = (path, thisobs, startstr, stopstr)
for doeclipse in eclipse:
# Set output filenames:
if doeclipse==True:
cname = '%s%s_chronological_eclipse_chart_%s--%s.txt' % format_params
sname = '%s%s_planet-sorted_eclipse_chart_%s--%s.txt' % format_params
else:
cname = '%s%s_chronological_transit_chart_%s--%s.txt' % format_params
sname = '%s%s_planet-sorted_transit_chart_%s--%s.txt' % format_params
# Generate transit charts:
ctext = transitChart(transiters, startstr, stopstr, obs=thisobs, \
eclipse=doeclipse, chron=True, **kw)
stext = transitChart(transiters, startstr, stopstr, obs=thisobs, \
eclipse=doeclipse, chron=False, **kw)
# Write files to disk:
if os.path.isfile(cname) and not clobber:
print "File %s exists and clobber=False; not writing file to disk." % cname
else:
f = open(cname, 'w')
f.writelines(ctext)
f.close()
if os.path.isfile(sname) and not clobber:
print "File %s exists and clobber=False; not writing file to disk." % sname
else:
f = open(sname, 'w')
f.writelines(stext)
f.close()
return