[AstroPy] problems with astroplan

Steven Boada boada at physics.rutgers.edu
Mon Nov 7 15:48:18 EST 2016


I Gautham,

OK, maybe my example was a little misleading. I mentioned what the 
example should do, but it isn't what I expect it to do.

Basically, I am trying to figure out if my object is observable from 
KPNO, and then I am going to use all the fancy scheduling stuff in 
astroplan to figure out which objects I want to observe when. The 
problem is that the line that prints false is checking whether or not my 
object is observable. I know it *is* observable, so I don't understand 
why it is printing false instead of true.

As Eric mentioned, it is probably something to do with the observation 
times, but I can't seem to find what I am missing. I want the example to 
print True True instead of True False.

Thanks for your help.

steven

On 11/07/2016 03:43 PM, Gautham Narayan wrote:
> Hi Steven,
>
> Maybe I'm missing something but you're example is supposed to print 
> True and then False. That's what is in the comments even.
>
>
> print(kpno.target_is_up(start_time, target))
> # should print True
>
> print(astroplan.is_observable(constraint, kpno, target[:1], 
> times=Time('2016-11-11')))
> # should print false.
>
> Cheers,
> -Gautham
>
>
>
>
> On 11/07/2016 12:43 PM, Steven Boada wrote:
>> Hi Eric,
>>
>> I apologize for my example not working. That is what I get for typing 
>> it out in the same console I had been testing things in. Here is a 
>> much more complete example.
>>
>> I've specified the timezone, but it still prints True and then False.
>>
>> import astroplan
>> from astroplan import Observer, FixedTarget
>> from astroplan.constraints import AtNightConstraint
>> from astropy.coordinates import SkyCoord
>> from astropy.time import Time
>>
>> # make telescope location
>> kpno = Observer.at_site('KPNO', timezone='MST')
>>
>> # make target coordinates
>> coords = SkyCoord(131.1331774, 62.41165761, unit='deg', frame='icrs')
>>
>> # make all the targets
>> target = [FixedTarget(name='test', coord=coords)]
>>
>> # make the observing time
>> start_time = Time('2016-11-10 18:54:00')
>> end_time = Time('2016-11-11 5:27:00')
>> time_delta = end_time - start_time
>> observable_time = start_time + time_delta * np.linspace(0,1,75)
>>
>> print(kpno.target_is_up(start_time, target))
>> # should print True
>>
>> # now we try to do all the fancy scheduling
>> # set our only constraint to be at night
>> constraint = AtNightConstraint.twilight_civil()
>>
>> print(astroplan.is_observable(constraint, kpno, target[:1], 
>> times=Time('2016-11-11')))
>> # should print false.
>>
>> Thanks again.
>>
>> On 11/07/2016 02:36 PM, Eric L. N. Jensen wrote:
>>> Hi Steven,
>>>
>>> Since you don’t specify a timezone on your start_time variable, I’m 
>>> guessing that it is probably being interpreted as UTC, in which case 
>>> your specified target isn’t up at KPNO.
>>>
>>> You don’t show an import statement that would define your call to 
>>> “Time” so I’m not 100% sure what routine it is and how it’s 
>>> interpreting the specified time, but being sure about timezones is 
>>> where I’d start troubleshooting this.
>>>
>>> Eric
>>>
>>>
>>>> On Nov 7, 2016, at 2:22 PM, Steven Boada 
>>>> <boada at physics.rutgers.edu> wrote:
>>>>
>>>> Hi list,
>>>>
>>>> I'm headed to KPNO and I'm trying out astroplan for the first time. 
>>>> But I'm getting some confusing output. Here's an example.
>>>>
>>>> from astroplan import Observer, FixedTarget
>>>> from astropy.coordinates import SkyCoord
>>>>
>>>> # make telescope location
>>>> kpno = Observer.at_site('KPNO')
>>>>
>>>> # make target coordinates
>>>> coords = SkyCoord(131.1331774, 62.41165761, unit='deg', frame='icrs')
>>>>
>>>> # make all the targets
>>>> target = [FixedTarget(name='test', coord=coords)]
>>>>
>>>> # make the observing time
>>>> start_time = Time('2016-11-11 01:54:00')
>>>> end_time = Time('2016-11-11 12:30:00')
>>>> time_delta = end_time - start_time
>>>> observable_time = start_time + time_delta * np.linspace(0,1,75)
>>>>
>>>> print(kpno.target_is_up(start_time, target))
>>>> # should print True
>>>>
>>>> # now we try to do all the fancy scheduling
>>>> # set our only constraint to be at night
>>>> constraint = AtNightConstraint.twilight_civil()
>>>>
>>>> print(astroplan.is_observable(constraint, kpno, targets[:1], 
>>>> times=Time('2016-11-11')))
>>>> # should print false.
>>>>
>>>>
>>>> Looking up the airmass etc. on the web, the target is certainly 
>>>> visible from KPNO. I'm obviously missing something, but I can't 
>>>> seem to figure out what it is.
>>>>
>>>> Thanks for your help.
>>>>
>>>>
>>>> steven
>>>>
>>>>
>>>> -- 
>>>>
>>>> Steven Boada
>>>>
>>>> Postdoctoral Researcher
>>>> Rutgers University
>>>> boada at physics.rutgers.edu
>>>>
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>>
>
>

-- 

Steven Boada

Postdoctoral Researcher
Rutgers University
boada at physics.rutgers.edu




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