get_next_moon can return times during daytime

[baileyji]

What happened?

ScopeSim/scopesim/utils.py

Lines 1218 to 1240 in 595a86b

	def get_next_moon(moontype="full"):
	"""
	Get time of the next closest moon phase of given moon type (full, half or new).
	"""
	times = Time.now() + np.linspace(0, 30, 1000)*u.day
	phases = get_moon_phase(times)
	flis = get_moon_fli(phases)
	next_full = times[np.argmax(flis)]
	next_new = times[np.argmin(flis)]
	prev_full = next_full - 29.53*u.day
	prev_new = next_new - 29.53*u.day
	if min(next_new, next_full) - Time.now() > Time.now() - max(prev_new, prev_full):
	next_half = min(next_new, next_full) - 7.38*u.day
	else:
	next_half = min(next_new, next_full) + 7.38*u.day
	if moontype == "full":
	return next_full.isot.split('T')[0]+"T00:00:00"
	elif moontype == "new":
	return next_new.isot.split('T')[0]+"T00:00:00"
	elif moontype == "half":
	return next_half.isot.split('T')[0]+"T00:00:00"
	else:
	raise ValueError(f"Invalid moon type: {moontype}, should be 'full', 'new' or 'half'.")

Likely should be location aware

Code to reproduce

Exception traceback

ScopeSim bug_report()

IRDB installation

I'm creating my own instrument package

Use case

Other

[Yashvi-Sharma]

Moon phase does not depend on location? Time.now() returns UTC time. is_night() and resolve_time() take care of the location/timezone checking.

ScopeSim/scopesim/utils.py

Lines 1132 to 1189 in 595a86b

	def is_night(obstime: Time, location: EarthLocation, return_midnight: bool = True) -> (bool | Time):
	"""
	Checks if the sun is below the horizon at the given observation time and location.
	If return_midnight is True, it returns the local midnight time of the same day if the sun is not below the horizon,
	otherwise it returns True or False.
	"""
	altaz = AltAz(obstime=obstime, location=location)
	sun = get_sun(obstime).transform_to(altaz)
	if sun.alt >= 0.0 * u.deg:
	logger.warning("Obstime is not after sunset!")
	if return_midnight:
	tlocal = Time(obstime.isot.split("T")[0] + "T00:00:00", format="isot", location=location) # local midnight
	utcoffset = (location.lon.deg / 15.) * u.hour
	newtime = tlocal - utcoffset # midnight in utc
	logger.info(f"Setting obstime to midnight of the same day. New UTC time is {newtime.isot}.")
	return newtime
	else:
	return False
	return True
	def resolve_time(time_str, location: EarthLocation | None = None):
	"""
	Parses the time input.
	Checks if the time is in MJD, or ISOT format, or indicates sky brightness ["bright", "gray", "dark"].
	If it is supplied as a sky brightness string, the next corresponding moon phase time is calculated and used.
	If the parsed time is not after sunset, the corresponding midnight time of that date is returned.
	"""
	t = None
	if isinstance(time_str, int) or isinstance(time_str, float): ## if time_str is a numeric MJD value
	logger.info(f"Resolving time: {time_str} assuming MJD format and UTC scale")
	try:
	t = Time(time_str, format="mjd", location=location)
	except Exception as e:
	logger.warning(f"Failed to parse time from {time_str}: {e}. Defaulting to 'dark'.")
	time_str = "dark"
	elif isinstance(time_str, str):
	if ('T' in time_str) and (':' in time_str): ## ISOT format
	logger.info(f"Resolving time: {time_str} assuming ISOT format and UTC scale")
	t = Time(time_str, format="isot", location=location)
	elif time_str not in ["bright", "gray", "dark"]:
	logger.warning(f"Unrecognized time string input: {time_str}. Defaulting to 'dark'.")
	time_str = "dark"
	else:
	logger.warning(f"Invalid time input type: {type(time_str)}, should be a string or numeric MJD value. Defaulting to 'dark'.")
	time_str = "dark"
	if t is None:
	kw = {"bright":"full", "gray":"half", "dark":"new"}
	t = Time(get_next_moon(kw[time_str]), format="isot", location=location)
	# check if t is at night
	if location is not None:
	nighttime = is_night(t, location, return_midnight=True)
	if isinstance(nighttime, Time):
	t = nighttime
	return t

[baileyji]

The phase doesn't, but the next time it is in that phase and above the horizon might not correspond to nighttime for a given observatory. Take a gander at the warnings in playground on my develop branch.

[Yashvi-Sharma]

That's what I said, it is calculating the next time in UTC, then is_night() checks with that UTC time and location the altitude of sun and gives a warning if it is not during nighttime, and then it takes only that date and calculates the UTC time for that location's midnight and returns that. It is not going to be the exact phase of new moon or full moon but it is close enough to dark or bright time that the user is asking