Module extinctionmodels

Get the "model" extinction at a certain longitude and latitude.

Find the predicted V-band extinction (Av) based on three dimensional models of the galactic interstellar extinction. The user can choose between different models by setting the model keyword:

1) "arenou": model from Arenou et al. (1992). 2) "schlegel": model from Schlegel et al. (1998) 3) "drimmel": model from Drimmel et al. (2003) 4) "marshall": model from Marshall et al. (2006)

example useage:

1. Find the total galactic extinction for a star at galactic lattitude 10.2 and longitude 59.0 along the line of sight, as given by the model of Arenou et al. (1992)

   >>> lng = 10.2
   >>> lat = 59.0
   >>> av = findext(lng, lat, model='arenou')
   >>> print("Av at lng = %.2f, lat = %.2f is %.2f magnitude" %(lng, lat, av))
   Av at lng = 10.20, lat = 59.00 is 0.05 magnitude

2. Find the extinction for a star at galactic lattitude 107.05 and longitude -34.93 and a distance of 144.65 parsecs, as given by the model of Arenou et al. (1992)

   >>> lng = 107.05
   >>> lat = -34.93
   >>> dd  = 144.65
   >>> av = findext(lng, lat, distance = dd, model='arenou')
   >>> print("Av at lng = %.2f, lat = %.2f and distance = %.2f parsecs is %.2f magnitude" %(lng, lat, dd, av))
   Av at lng = 107.05, lat = -34.93 and distance = 144.65 parsecs is 0.15 magnitude

3. Find the Marschall extinction for a star at galactic longitude 10.2 and latitude 9.0. If the distance is not given, we return the complete extinction along the line of sight (i.e. put the star somewhere out of the galaxy).

   >>> lng = 10.2
   >>> lat = 9.0
   >>> av = findext(lng, lat, model='marshall')
   >>> print("Av at lng = %.2f, lat = %.2f is %.2f magnitude" %(lng, lat, av))
   Av at lng = 10.20, lat = 9.00 is 10.67 magnitude

4. Find the Marshall extinction for a star at galactic lattitude 271.05 and longitude -4.93 and a distance of 144.65 parsecs, but convert to Av using Rv = 2.5 instead of Rv = 3.1

   >>> lng = 271.05
   >>> lat = -4.93
   >>> dd  = 144.65
   >>> av = findext(lng, lat, distance = dd, model='marshall', Rv=2.5)
   >>> print("Av at lng = %.2f, lat = %.2f and distance = %.2f parsecs is %.2f magnitude" %(lng, lat, dd, av))
   Av at lng = 271.05, lat = -4.93 and distance = 144.65 parsecs is 13.95 magnitude

5. Find the extinction for a star at galactic longitude 10.2 and latitude 9.0, using the schlegel model, using Rv=2.9 instead of Rv=3.1

   >>> lng = 58.2
   >>> lat = 24.0
   >>> distance = 848.
   >>> av = findext(lng, lat, distance=distance)
   >>> print("Av at lng = %.2f, lat = %.2f is %.2f magnitude" %(lng, lat, av))
   Av at lng = 58.20, lat = 24.00 is 0.12 magnitude

REMARKS: a) Schlegel actually returns E(B-V), this value is then converted to Av (the desired value for Rv can be set as a keyword; standard sets Rv=3.1) b) Schlegel is very dubious for latitudes between -5 and 5 degrees c) Marschall actually returns Ak, this value is then converted to Av (the reddening law and Rv can be set as keyword; standard sets Rv=3.1, redlaw='cardelli1989') d) Marschall is only available for certain longitudes and latitudes: 0 < lng < 100 or 260 < lng < 360 and -10 < lat < 10

Parameters:

• lng (float) - Galactic Longitude (in degrees)
• lat (float) - Galactic Lattitude (in degrees)
• model (str) - the name of the extinction model: ("arenou", "schlegel", "drimmel" or "marshall"; if none given, the program uses "drimmel")
• distance (float) - Distance to the source (in parsecs), if the distance is not given, the total galactic extinction along the line of sight is calculated

Returns: float

The extinction in Johnson V-band

Find the predicted V-band extinction (Av) according to the 3D model for galactic extinction of Arenou et al, "Modelling the Galactic interstellar extinction distribution in three dimensions", Arenou et al, "A tridimensional model of the galactic interstellar extinction" published in Astronomy and Astrophysics (ISSN 0004-6361), vol. 258, no. 1, p. 104-111, 1992

Example usage:

1. Find the extinction for a star at galactic lattitude 10.2 and longitude 59.0. If the distance is not given, we use the maximal distance r0 for that line of sight, as given in the Appendix of Arenou et al. (1992)

   >>> lng = 10.2
   >>> lat = 59.0
   >>> av = findext_arenou(lng, lat)
   >>> print("Av at lng = %.2f, lat = %.2f is %.2f magnitude" %(lng, lat, av))
   Av at lng = 10.20, lat = 59.00 is 0.05 magnitude

2. Find the extinction for a star at galactic lattitude 107.05 and longitude -34.93 and a distance of 144.65 parsecs

   >>> lng = 107.05
   >>> lat = -34.93
   >>> dd  = 144.65
   >>> av = findext_arenou(lng, lat, distance = dd)
   >>> print("Av at lng = %.2f, lat = %.2f and distance = %.2f parsecs is %.2f magnitude" %(lng, lat, dd, av))
   Av at lng = 107.05, lat = -34.93 and distance = 144.65 parsecs is 0.15 magnitude

Parameters:

• ll (float) - Galactic Longitude (in degrees)
• bb (float) - Galactic Lattitude (in degrees)
• distance (float) - Distance to the source (in parsecs)

Returns: float

The extinction in Johnson V-band

  Read in the Marshall data
  
This function is memoized.

Decorators:

• @memoized

Find the V-band extinction according to the reddening model of Marshall et al. (2006) published in Astronomy and Astrophysics, Volume 453, Issue 2, July II 2006, pp.635-651

The band in which the extinction is calculated is actually optional, and given with the keyword norm. If you set norm='Av', you get visual extinction (in JOHNSON.V) band, if you set norm='Ak', you get infrared extinction (in JOHNSON.K). If you want the extinction in different passbands, you can set them via norm='GENEVA.V'. So, norm='Av' is equivalent to setting norm='JOHNSON.V'.

Example usage:

1. Find the extinction for a star at galactic longitude 10.2 and latitude 9.0. If the distance is not given, we return the complete extinction along the line of sight (i.e. put the star somewhere out of the galaxy).

   >>> lng = 10.2
   >>> lat = 9.0
   >>> ak = findext_marshall(lng, lat, norm='Ak')
   >>> print("Ak at lng = %.2f, lat = %.2f is %.2f magnitude" %(lng, lat, ak))
   Ak at lng = 10.20, lat = 9.00 is 0.15 magnitude

2. Find the extinction for a star at galactic lattitude 271.05 and longitude -4.93 and a distance of 144.65 parsecs

   >>> lng = 271.05
   >>> lat = -4.93
   >>> dd  = 144.65
   >>> ak = findext_marshall(lng, lat, distance = dd, norm='Ak')
   >>> print("Ak at lng = %.2f, lat = %.2f and distance = %.2f parsecs is %.2f magnitude" %(lng, lat, dd, ak))
   Ak at lng = 271.05, lat = -4.93 and distance = 144.65 parsecs is 0.02 magnitude

3. The extinction for galactic longitude 10.2 and latitude 59.0 can not be calculated using the Marshall models, because they are only valid at certain lng and lat (0 < lng < 100 or 260 < lng < 360, -10 < lat < 10)

>>> lng = 10.2
>>> lat = 59.0
>>> ak = findext_marshall(lng, lat, norm='Ak')
>>> print(ak)
None

Parameters:

• ll (float) - Galactic Longitude (in degrees) should be between 0 and 100 or 260 and 360 degrees
• bb (float) - Galactic Lattitude (in degrees) should be between -10 and 10 degrees
• distance (float) - Distance to the source (in parsecs)
• redlaw (str) - the used reddening law (standard: 'cardelli1989')
• Rv (float) - Av/E(B-V) (standard: 3.1)

Returns: float

The extinction in V-band (or norm)

Procedure to retrieve the absorption in V from three-dimensional grids, based on the Galactic dust distribution of Drimmel & Spergel.

Example usage:

1. Find the extinction for a star at galactic longitude 10.2 and latitude 9.0. If the distance is not given, we return the complete extinction along the line of sight (i.e. put the star somewhere out of the galaxy).

   >>> lng = 10.2
   >>> lat = 9.0
   >>> av = findext_drimmel(lng, lat)
   >>> print("Av at lng = %.2f, lat = %.2f is %.2f magnitude" %(lng, lat, av))
   Av at lng = 10.20, lat = 9.00 is 1.24 magnitude

2. Find the extinction for a star at galactic lattitude 107.05 and longitude -34.93 and a distance of 144.65 parsecs

   >>> lng = 271.05
   >>> lat = -4.93
   >>> dd  = 144.65
   >>> ak = findext_marshall(lng, lat, distance = dd)
   >>> print("Ak at lng = %.2f, lat = %.2f and distance = %.2f parsecs is %.2f magnitude" %(lng, lat, dd, ak))
   Ak at lng = 271.05, lat = -4.93 and distance = 144.65 parsecs is 0.02 magnitude

Parameters:

• lng (float) - Galactic Longitude (in degrees)
• lat (float) - Galactic Lattitude (in degrees)
• distance (float) - Distance to the source (in parsecs)
• rescaling (boolean) - Rescaling needed or not?

Returns: float

extinction in V band with/without rescaling

Decorators:

• @memoized

Get the "Schlegel" extinction at certain longitude and latitude

This function returns the E(B-V) maps of Schlegel et al. (1998), depending on wether the distance is given or not, the E(B-V) value is corrected. If distance is set we use the distance-corrected values:

E(B-V) = E(B-V)_maps * (1 - exp(-10 * r * sin(|b|))) where E(B-V) is the value to be used and E(B-V)_maps the value as found with the Schlegel dust maps

Then we convert the E(B-V) to Av. Standard we use Av = E(B-V)*Rv with Rv=3.1, but the value of Rv can be given as a keyword.

! WARNING: the schlegel maps are not usefull when |b| < 5 degrees !

avdisk

Value:

array([[[ 1.4955765 , 1.51041055, 1.52583313, ..., 14.16928196, 14.33589268, 14.50690556], [ 1.49150336, 1.50631094, 1.52171242, ..., 14.25491714, 14.42823792, 14.6043644 ], [ 1.48738921, 1.50216699, 1.51754415, ..., 14.34758663, 14.52599049, 14.70586777], ..., [ 1.13166916, 1.13840032, 1.14543295, ..., 13.64110756, ...

avloc

Value:

array([[[ 0.51059103, 0.50907248, 0.50760478, ..., 0.55334765, 0.55604851, 0.55879277], [ 0.50627148, 0.50473255, 0.5032438 , ..., 0.5490455 , 0.55175978, 0.55451769], [ 0.50197417, 0.50041586, 0.49890628, ..., 0.54475415, 0.54748213, 0.55025381], ..., [ 0.45234904, 0.45094237, 0.44959182, ..., 0.52910644, ...

avspir

Value:

array([[[ 0.03569764, 0.03420052, 0.03268857, ..., 1.38737524, 1.43040562, 1.47390473], [ 0.03654352, 0.03497045, 0.03350747, ..., 1.41928446, 1.46210182, 1.50381613], [ 0.03744392, 0.03583845, 0.03428919, ..., 1.44910383, 1.4893527 , 1.52848864], ..., [ 0.23173086, 0.23290038, 0.23394479, ..., 0.7445206 , ...

avdloc

Value:

array([[[ 0.25433207, 0.24842149, 0.24276738, ..., 0.26471582, 0.27269766, 0.28105965], [ 0.24726538, 0.24116401, 0.23531477, ..., 0.25683123, 0.26499909, 0.27354625], [ 0.24051285, 0.23421949, 0.22817302, ..., 0.24926975, 0.25762734, 0.26636243], ..., [ 0.23173071, 0.22590324, 0.2203003 , ..., 0.24627914, ...

avori

Value:

array([[[ 1.37120429e-02, 1.63412001e-02, 1.94005072e-02, ..., 5.95959888e-15, 5.99463597e-15, 6.03022491e-15], [ 1.26305996e-02, 1.51010454e-02, 1.79849099e-02, ..., 5.90241230e-15, 5.93778693e-15, 5.97371468e-15], [ 1.16044367e-02, 1.39205093e-02, 1.66331585e-02, ..., 5.84544552e-15, 5.88116278e-15, 5.91743358e-15], ..., [ 8.16510574e-12, 2.29976216e-09, 4.68663952e-09, ..., ...

coordinates

Value:

FITS_rec([(1.0, 118.8959, 6.4741001), (32.0, 133.4691, -40.774502), (38.0, 128.32899, -2.1266999), (91.0, 153.8748, 0.28259999), (100.0, 163.8517, -6.9454999), (127.0, 192.57401, -17.1416), (166.0, 210.34171, -15.5775), (173.0, 213.9559, -15.9047), (177.0, 154.27589, 17.4807), (179.0, 176.29401, 6.3464999), (191.0, 182.99809, 4.3060999), (196.0, 167.41431, 12.8883), (202.0, 246.6821, -23.914301), (218.0, 177.98911, 11.2576), (220.0, 194.13589, 3.0009), (229.0, 234.82381, -15.4124), ...

avgrid

Value:

array([[[ 1.53127408, 1.5446111 , 1.55852175, ..., 15.55665684, 15.76629829, 15.98081017], [ 1.52804685, 1.54128134, 1.55521989, ..., 15.67420197, 15.89033985, 16.108181 ], [ 1.52483308, 1.53800547, 1.55183339, ..., 15.79668999, 16.01534271, 16.23435593], ..., [ 1.36339998, 1.3713007 , 1.37937772, ..., 14.38562775, ...

avori2

Value:

array([[[ 6.74924115e-04, 7.81801646e-04, 8.86501570e-04, ..., 2.64837877e-06, 2.14805345e-06, 1.74239563e-06], [ 6.11458207e-04, 7.02597725e-04, 8.05983378e-04, ..., 2.33851642e-06, 1.89349714e-06, 1.53337783e-06], [ 5.52941929e-04, 6.36523997e-04, 7.31527805e-04, ..., 2.06035520e-06, 1.66541224e-06, 1.34641925e-06], ..., [ 1.77380842e-13, 2.56713731e-13, 3.70240622e-13, ..., ...

rf_allsky

Value:

FITS_rec([(12.537686, 312.5304, 1.0, 218453.0, 0.88002169), (12.59496, 312.15927, 1.0, 218452.0, 0.92727238), (12.6505, 311.79578, 1.0, 218449.0, 1.0062375), ..., (52.684265, 27.530857, 1.0, 43694.0, 1.0541877), (52.361267, 27.273281, 1.0, 43691.0, 1.0950361), (52.030758, 27.013985, 1.0, 43690.0, 0.83686513)], dtype=(numpy.record, [('glat', '>f4'), ('glng', '>f4'), ('ncomp' , '>f4'), ('pnum', '>f4'), ('rfac', '>f4')]))

glat

Value:

array([ 12.53768635, 12.59496021, 12.6505003 , ..., 52.68426514, 52.36126709, 52.0307579 ], dtype=float32)

glng

Value:

array([ 312.53039551, 312.15927124, 311.79577637, ..., 27.53085709 , 27.2732811 , 27.01398468], dtype=float32)

pnum

Value:

array([ 218453., 218452., 218449., ..., 43694., 43691., 43690. ], dtype=float32)

rfac

Value:

array([ 0.88002169, 0.92727238, 1.00623751, ..., 1.05418766, 1.09503615, 0.83686513], dtype=float32)

g2e

Value:

array([[ -5.48824860e-02, -9.93821033e-01, -9.64762490e-02], [ 4.94116468e-01, -1.10993846e-01, 8.62281440e-01], [ -8.67661702e-01, -3.46354000e-04, 4.97154957e-01]])