astLib.astCoords

Package astLib :: Module astCoords |
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# Module astCoords

source code

module for coordinate manipulation (conversions, calculations etc.)

(c) 2007-2012 Matt Hilton

(c) 2013-2014 Matt Hilton & Steven Boada

http://astlib.sourceforge.net

Functions | [hide private]
float |
hms2decimal(RAString, delimiter) Converts a delimited string of Hours:Minutes:Seconds format into decimal degrees. | source code
float |
dms2decimal(decString, delimiter) Converts a delimited string of Degrees:Minutes:Seconds format into decimal degrees. | source code
string |
decimal2hms(RADeg, delimiter) Converts decimal degrees to string in Hours:Minutes:Seconds format with user specified delimiter. | source code
string |
decimal2dms(decDeg, delimiter) Converts decimal degrees to string in Degrees:Minutes:Seconds format with user specified delimiter. | source code
float or numpy array, depending upon type of RADeg2, decDeg2 |
calcAngSepDeg(RADeg1, decDeg1, RADeg2, decDeg2) Calculates the angular separation of two positions on the sky (specified in decimal degrees) in decimal degrees, assuming a tangent plane projection (so separation has to be <90 deg). | source code
float [newRA, newDec] |
shiftRADec(ra1, dec1, deltaRA, deltaDec) Computes new right ascension and declination shifted from the original by some delta RA and delta DEC. | source code
list |
convertCoords(inputSystem, outputSystem, coordX, coordY, epoch) Converts specified coordinates (given in decimal degrees) between J2000, B1950, and Galactic. | source code
list |
calcRADecSearchBox(RADeg, decDeg, radiusSkyDeg) Calculates minimum and maximum RA, dec coords needed to define a box enclosing a circle of radius radiusSkyDeg around the given RADeg, decDeg coordinates. | source code

Function Details | [hide private]

### hms2decimal(RAString, delimiter) | source code
Converts a delimited string of Hours:Minutes:Seconds format into decimal degrees. Parameters: `RAString` (string) - coordinate string in H:M:S format `delimiter` (string) - delimiter character in RAString Returns: float coordinate in decimal degrees

### dms2decimal(decString, delimiter) | source code
Converts a delimited string of Degrees:Minutes:Seconds format into decimal degrees. Parameters: `decString` (string) - coordinate string in D:M:S format `delimiter` (string) - delimiter character in decString Returns: float coordinate in decimal degrees

### decimal2hms(RADeg, delimiter) | source code
Converts decimal degrees to string in Hours:Minutes:Seconds format with user specified delimiter. Parameters: `RADeg` (float) - coordinate in decimal degrees `delimiter` (string) - delimiter character in returned string Returns: string coordinate string in H:M:S format

### decimal2dms(decDeg, delimiter) | source code
Converts decimal degrees to string in Degrees:Minutes:Seconds format with user specified delimiter. Parameters: `decDeg` (float) - coordinate in decimal degrees `delimiter` (string) - delimiter character in returned string Returns: string coordinate string in D:M:S format

### calcAngSepDeg(RADeg1, decDeg1, RADeg2, decDeg2) | source code
Calculates the angular separation of two positions on the sky (specified in decimal degrees) in decimal degrees, assuming a tangent plane projection (so separation has to be <90 deg). Note that RADeg2, decDeg2 can be numpy arrays. Parameters: `RADeg1` (float) - R.A. in decimal degrees for position 1 `decDeg1` (float) - dec. in decimal degrees for position 1 `RADeg2` (float or numpy array) - R.A. in decimal degrees for position 2 `decDeg2` (float or numpy array) - dec. in decimal degrees for position 2 Returns: float or numpy array, depending upon type of RADeg2, decDeg2 angular separation in decimal degrees

### shiftRADec(ra1, dec1, deltaRA, deltaDec) | source code
Computes new right ascension and declination shifted from the original by some delta RA and delta DEC. Input position is decimal degrees. Shifts (deltaRA, deltaDec) are arcseconds, and output is decimal degrees. Based on an IDL routine of the same name. Parameters: `ra1` (R.A. in decimal degrees) - float `dec1` (dec. in decimal degrees) - float `deltaRA` (shift in R.A. in arcseconds) - float `deltaDec` (shift in dec. in arcseconds) - float Returns: float [newRA, newDec] shifted R.A. and dec.

### convertCoords(inputSystem, outputSystem, coordX, coordY, epoch) | source code
Converts specified coordinates (given in decimal degrees) between J2000, B1950, and Galactic. Parameters: `inputSystem` (string) - system of the input coordinates (either "J2000", "B1950" or "GALACTIC") `outputSystem` (string) - system of the returned coordinates (either "J2000", "B1950" or "GALACTIC") `coordX` (float) - longitude coordinate in decimal degrees, e.g. R. A. `coordY` (float) - latitude coordinate in decimal degrees, e.g. dec. `epoch` (float) - epoch of the input coordinates Returns: list coordinates in decimal degrees in requested output system

### calcRADecSearchBox(RADeg, decDeg, radiusSkyDeg) | source code
Calculates minimum and maximum RA, dec coords needed to define a box enclosing a circle of radius radiusSkyDeg around the given RADeg, decDeg coordinates. Useful for freeform queries of e.g. SDSS, UKIDSS etc.. Uses calcAngSepDeg, so has the same limitations. Parameters: `RADeg` (float) - RA coordinate of centre of search region `decDeg` (float) - dec coordinate of centre of search region `radiusSkyDeg` (float) - radius in degrees on the sky used to define search region Returns: list [RAMin, RAMax, decMin, decMax] - coordinates in decimal degrees defining search box