Spectra [contents] [index]

spectra ""

List of input spectra

specnum "0"

Spectrum number(s) if multispec file

specdir ""

Directory for input spectra

specsky no

Is spectrum twilight sky? (yes or no) If yes, earth-sun direction is used to compute the velocity corrections. The BCV and HCV will be close but not identical because the direction to the center of the sun's light is not the same as the direction to the solar system barycenter.

subgrav no

Subtract solar gravitational redshift from twilight sky (yes or no) If subgrav=yes and specsky=yes, subtract a correction for the sun's gravity (0.636) from the barycentric and heliocentric corrections computed by the program. If savebcv=yes, BCV, HCV, and SGRV are written to the image header. HCV, the velocity of the sun relative to the spectrograph with the gravitational correction subtracted, should be used as the spectrum correction

rvsao.svel_corr=heliocentric

when cross-correlating twilight spectra with XCSAO.

Sky direction [contents] [index]

keyra "RA"

Right ascension header keyword

keydec "DEC"

Declination header keyword

keyeqnx "EPOCH"

Coordinate equinox header keyword

ra INDEF

Right ascension of observation. If not INDEF, it is expected to be in the format hh:mm:ss.sss or decimal hours.

dec INDEF

Declination of observation. If not INDEF, it is expected to be in the format dd:mm:ss.sss or decimal degrees.

equinox 1950.0

Epoch of equinox (usually 1950.0 or 2000.0) of coordinates.

Timing [contents] [index]

keyhjd "HJD"

Header keyword for Heliocentric Julian date at midtime of observation. This date is used for logging purposes, NOT for computation of the barycentric velocity correction.

keyjd "JD"

Header keyword for Geocentric Julian date at middle of observation. If this parameter is present, no other time is needed.

keydate "DATE-OBS"

Header keyword for date of observation (dd/mm/yyyy)

keystart "UTOPEN"

Header keyword for UT at start of observation

keymid "UTMID"

Header keyword for UT in middle of observation

keyend "UT"

Header keyword for UT at end of observation

keyexp "EXPOSURE"

Header keyword for duration of observation in seconds. If keymid is not present, half the exposure duration is added to keystart or subtracted from keyend.

hjd 0.0

Heliocentric Julian Date of observation (only used if > 0)

gjd 0.0

Julian Date of observation (only used if > 0)

year INDEF

UT year of observation (only used if not INDEF)

month INDEF

UT month of observation (only used if not INDEF)

day INDEF

UT day of month of observation (only used if not INDEF)

ut INDEF

Universal Time of observation (only used if not INDEF)

Observatory Location [contents] [index]

obsname "file"

Observatory name. If "file", read from image header using the following keywords. Otherwise, look it up in IRAF's observatory database. If the string is not found there, use the position given by the parameters below.

keyobs "SITENAME"

Observatory name header keyword

keylat "SITELAT"

Observatory latitude header keyword

keylong "SITELONG"

Observatory longitude header keyword

keyalt "SITEALT"

Observatory altitude header keyword

obslong 0.0

Observatory longitude, used if obsname is not found.

obslat 0.0

Observatory latitude, used if obsname is not found.

obsalt 0.0

Observatory altitude in meters, used if obsname is not found.

Results [contents] [index]

savebcv no

Save computed BCV and HCV in data file header (yes or no)

savejd no

Save computed GJD (as GJDN), HJD (as HJDN), and midtime (as UTMID) in data file header (yes or no)

bcv

Computed barycentric velocity (returned)

hcv

Computed heliocentric velocity (returned)

verbose yes

Displays heliocentric and barycentric corrections

printmode 1

1=Display heliocentric and barycentric corrections and ancillary data
2=Display only BCV

debug no

Displays intermediate results

BCVCORR Parameters, Alphabetically