Bases: KPFTranslatorFunction
Estimate the exposure time given the stellar Gmag and which camera.
Based on scaling from a single, poorly measured data point:
For Vmag ~ 4, the SCIFVC_exptime = 1 and CAHKFVC_exptime = 15
| Parameters: |
-
Gmag
(float)
–
The G magnitude of the target.
|
Source code in kpf/fvc/PredictFVCParameters.py
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62 | class PredictFVCParameters(KPFTranslatorFunction):
'''Estimate the exposure time given the stellar Gmag and which camera.
Based on scaling from a single, poorly measured data point:
For Vmag ~ 4, the SCIFVC_exptime = 1 and CAHKFVC_exptime = 15
Args:
Gmag (float): The G magnitude of the target.
'''
@classmethod
def pre_condition(cls, args):
check_input(args, 'Gmag', allowed_types=[int, float])
@classmethod
def perform(cls, args):
Gmag = args.get('Gmag')
delta_mag = 4 - Gmag
flux_ratio = 10**(delta_mag/2.5)
if flux_ratio > 10:
exptime = {'SCI': 0.1,
'CAHK': 1.5}
elif flux_ratio > 5:
exptime = {'SCI': 0.2,
'CAHK': 3}
elif flux_ratio > 2:
exptime = {'SCI': 0.5,
'CAHK': 8}
elif flux_ratio > 0.5:
exptime = {'SCI': 1,
'CAHK': 15}
elif flux_ratio > 0.2:
exptime = {'SCI': 5,
'CAHK': 15}
elif flux_ratio > 0.05:
exptime = {'SCI': 10,
'CAHK': 15}
result = {'SCIFVC_exptime': exptime['SCI'],
'CAHKFVC_exptime': exptime['CAHK']}
print(result)
if args.get('set', False):
SetFVCExpTime.execute({'camera': 'SCI', 'exptime': exptime['SCI']})
SetFVCExpTime.execute({'camera': 'CAHK', 'exptime': exptime['CAHK']})
return result
@classmethod
def post_condition(cls, args):
pass
@classmethod
def add_cmdline_args(cls, parser):
parser.add_argument('Gmag', type=float,
help="The G magnitude of the target")
parser.add_argument("--set", dest="set",
default=False, action="store_true",
help="Set these values after calculating?")
return super().add_cmdline_args(parser)
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