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AutoPlatepar/AstrometryNet: optional position_hint for star-starved solves #967

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b2a8da4
feat(astrometry): optional position_hint for astrometry.net solves
GlassOnTin Aug 18, 2026
1d54f4e
Fix position hint propagation and add coverage
dvida Aug 24, 2026
b83ed7f
astrometry: clamp position-hint radius to the field size
GlassOnTin Aug 24, 2026
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62 changes: 47 additions & 15 deletions RMS/Astrometry/AstrometryNet.py
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@

def astrometryNetSolveLocal(ff_file_path=None, img=None, mask=None, x_data=None, y_data=None,
fov_w_range=None, fov_w_hint=None, max_stars=100, verbose=False, x_center=None, y_center=None,
lat=None, lon=None, jd=None, input_intensities=None):
lat=None, lon=None, jd=None, input_intensities=None, position_hint=None):
""" Find an astrometric solution of X, Y image coordinates of stars detected on an image using the
local installation of astrometry.net.

Expand All @@ -52,6 +52,9 @@ def astrometryNetSolveLocal(ff_file_path=None, img=None, mask=None, x_data=None,
lon: [float] Station longitude in degrees. Required for iterative matching.
jd: [float] Julian date. Required for iterative matching.
input_intensities: [ndarray] Star intensities for brightness-based matching. Optional.
position_hint: [tuple] Optional (ra_deg, dec_deg, radius_deg). When given, astrometry.net is
told roughly where the field is, collapsing the blind all-sky search to that patch --
which lets narrow-FOV / faint cameras solve with far fewer stars. None = blind (default).

Returns:
[tuple] A tuple containing the following elements:
Expand Down Expand Up @@ -207,6 +210,7 @@ def astrometryNetSolveLocal(ff_file_path=None, img=None, mask=None, x_data=None,
scales = {14, 15, 16, 17, 18, 19}

size_hint = None
avg_fov_w = fov_h = None # set below when a FOV estimate is available

if fov_w_range is not None:

Expand Down Expand Up @@ -324,6 +328,30 @@ def astrometryNetSolveLocal(ff_file_path=None, img=None, mask=None, x_data=None,
)
)

# Optional position hint: when the caller knows roughly where the camera points (e.g. a
# previous platepar, or a known station pointing), this collapses the blind all-sky search
# to a small patch, letting narrow-FOV / faint cameras solve with far fewer stars than a
# blind solve needs. None (the default) preserves the original blind behaviour.
position_hint_obj = None
if position_hint is not None:
ra_hint, dec_hint, radius_hint = position_hint

# The local solver restricts the reference catalog to within radius_hint of the hint
# centre. If that radius is smaller than the image's own angular field, the outer stars
# get excluded and the quad match fails - a regression on wide-FOV cameras (e.g. a 15 deg
# hint on a ~64 deg fisheye drops everything past 15 deg from centre). Never let the hint
# be tighter than the field's circum-radius (half-diagonal, small margin). Only when a
# FOV estimate is available (it always is from autoFitPlatepar).
if avg_fov_w is not None and fov_h is not None:
field_radius = np.hypot(avg_fov_w, fov_h)/2.0*1.1
radius_hint = max(float(radius_hint), field_radius)

position_hint_obj = astrometry.PositionHint(
ra_deg=float(ra_hint), dec_deg=float(dec_hint), radius_deg=float(radius_hint))
if verbose:
print("Using position hint: RA={:.2f} Dec={:.2f} radius={:.1f} deg (>= field radius)".format(
ra_hint, dec_hint, radius_hint))

# If the solver.solve has the argument "stars", use a 2D array of stars instead of stars_xs and stars_ys
solve_args = inspect.getfullargspec(solver.solve).args
if "stars" in solve_args:
Expand All @@ -332,7 +360,7 @@ def astrometryNetSolveLocal(ff_file_path=None, img=None, mask=None, x_data=None,
solution = solver.solve(
stars=star_data,
size_hint=size_hint,
position_hint=None,
position_hint=position_hint_obj,
solution_parameters=solution_parameters
)

Expand All @@ -342,7 +370,7 @@ def astrometryNetSolveLocal(ff_file_path=None, img=None, mask=None, x_data=None,
stars_xs=x_data,
stars_ys=y_data,
size_hint=size_hint,
position_hint=None,
position_hint=position_hint_obj,
solution_parameters=solution_parameters
)

Expand Down Expand Up @@ -451,9 +479,9 @@ def astrometryNetSolveLocal(ff_file_path=None, img=None, mask=None, x_data=None,

def astrometryNetSolve(ff_file_path=None, img=None, mask=None, x_data=None, y_data=None, fov_w_range=None,
fov_w_hint=None, max_stars=100, verbose=False, x_center=None, y_center=None,
lat=None, lon=None, jd=None, input_intensities=None):
lat=None, lon=None, jd=None, input_intensities=None, position_hint=None):
""" Find an astrometric solution of X, Y image coordinates of stars detected on an image using the
local installation of astrometry.net.
local installation of astrometry.net or a compatible remote service.

Keyword arguments:
ff_file_path: [str] Path to the FF file to load.
Expand All @@ -471,10 +499,14 @@ def astrometryNetSolve(ff_file_path=None, img=None, mask=None, x_data=None, y_da
lon: [float] Station longitude in degrees. Required for iterative matching.
jd: [float] Julian date. Required for iterative matching.
input_intensities: [ndarray] Star intensities for brightness-based matching. Optional.
position_hint: [tuple] Optional (ra_deg, dec_deg, radius_deg). When given, astrometry.net is
told roughly where the field is, collapsing the blind all-sky search to that patch --
which lets narrow-FOV / faint cameras solve with far fewer stars. None = blind (default).
"""

# Helper to try coordinate-only first, then fall back to image if available
def _tryRemoteSolve(api_url, ff_path, image, x_coords, y_coords, fov_range, x_cen, y_cen):
def _tryRemoteSolve(api_url, ff_path, image, x_coords, y_coords, fov_range, x_cen, y_cen,
position_hint):
"""Try coordinate-only solve first, fall back to image if that fails."""

# If we have coordinates, try coordinate-only first (faster, less bandwidth)
Expand All @@ -484,7 +516,7 @@ def _tryRemoteSolve(api_url, ff_path, image, x_coords, y_coords, fov_range, x_ce
result = novaAstrometryNetSolve(
ff_file_path=None, img=None, x_data=x_coords, y_data=y_coords,
fov_w_range=fov_range, x_center=x_cen, y_center=y_cen,
api_url=api_url
api_url=api_url, position_hint=position_hint
)
if result is not None:
return result
Expand All @@ -498,15 +530,15 @@ def _tryRemoteSolve(api_url, ff_path, image, x_coords, y_coords, fov_range, x_ce
return novaAstrometryNetSolve(
ff_file_path=ff_path, img=image, x_data=None, y_data=None,
fov_w_range=fov_range, x_center=x_cen, y_center=y_cen,
api_url=api_url
api_url=api_url, position_hint=position_hint
)
return None

# No coordinates, just try with image
return novaAstrometryNetSolve(
ff_file_path=ff_path, img=image, x_data=x_coords, y_data=y_coords,
fov_w_range=fov_range, x_center=x_cen, y_center=y_cen,
api_url=api_url
api_url=api_url, position_hint=position_hint
)

# If the local installation of astrometry.net is not available, use remote API
Expand All @@ -518,7 +550,7 @@ def _tryRemoteSolve(api_url, ff_path, image, x_coords, y_coords, fov_range, x_ce
try:
result = _tryRemoteSolve(
PRIMARY_API_URL, ff_file_path, img, x_data, y_data,
fov_w_range, x_center, y_center
fov_w_range, x_center, y_center, position_hint
)
if result is not None:
return result
Expand All @@ -529,7 +561,7 @@ def _tryRemoteSolve(api_url, ff_path, image, x_coords, y_coords, fov_range, x_ce
print(f"Trying fallback server: {FALLBACK_API_URL}")
return _tryRemoteSolve(
FALLBACK_API_URL, ff_file_path, img, x_data, y_data,
fov_w_range, x_center, y_center
fov_w_range, x_center, y_center, position_hint
)

else:
Expand All @@ -540,7 +572,7 @@ def _tryRemoteSolve(api_url, ff_path, image, x_coords, y_coords, fov_range, x_ce
ff_file_path=ff_file_path, img=img, mask=mask, x_data=x_data, y_data=y_data,
fov_w_range=fov_w_range, fov_w_hint=fov_w_hint, max_stars=max_stars, verbose=verbose,
x_center=x_center, y_center=y_center,
lat=lat, lon=lon, jd=jd, input_intensities=input_intensities
lat=lat, lon=lon, jd=jd, input_intensities=input_intensities, position_hint=position_hint
)

# If local fails, try remote APIs
Expand All @@ -554,7 +586,7 @@ def _tryRemoteSolve(api_url, ff_path, image, x_coords, y_coords, fov_range, x_ce
try:
result = _tryRemoteSolve(
PRIMARY_API_URL, ff_file_path, img, x_data, y_data,
fov_w_range, x_center, y_center
fov_w_range, x_center, y_center, position_hint
)
if result is not None:
return result
Expand All @@ -565,7 +597,7 @@ def _tryRemoteSolve(api_url, ff_path, image, x_coords, y_coords, fov_range, x_ce
print(f"Trying fallback server: {FALLBACK_API_URL}")
return _tryRemoteSolve(
FALLBACK_API_URL, ff_file_path, img, x_data, y_data,
fov_w_range, x_center, y_center
fov_w_range, x_center, y_center, position_hint
)


Expand Down Expand Up @@ -628,4 +660,4 @@ def _tryRemoteSolve(api_url, ff_path, image, x_coords, y_coords, fov_range, x_ce
star['ra_deg'], star['dec_deg'], star['x_pix'], star['y_pix']))

else:
print("No solution found.")
print("No solution found.")
12 changes: 10 additions & 2 deletions RMS/Astrometry/AstrometryNetNova.py
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Original file line number Diff line number Diff line change
Expand Up @@ -282,7 +282,7 @@ def jobs_by_tag(self, tag, exact):


def novaAstrometryNetSolve(ff_file_path=None, img=None, x_data=None, y_data=None, fov_w_range=None,
api_key=None, x_center=None, y_center=None, api_url=None):
api_key=None, x_center=None, y_center=None, api_url=None, position_hint=None):
""" Find an astrometric solution of X, Y image coordinates of stars detected on an image using the
nova.astrometry.net service or a compatible API.

Expand All @@ -299,6 +299,7 @@ def novaAstrometryNetSolve(ff_file_path=None, img=None, x_data=None, y_data=None
y_center: [float] Y coordinate of the image center. If not given, the image center will be used.
api_url: [str] Custom API URL. None by default, in which case nova.astrometry.net will be used.
Can be set to use alternative servers like 'https://astro.contrailcast.com/api/'.
position_hint: [tuple] Optional (ra_deg, dec_deg, radius_deg) search-position hint.

Return:
(ra, dec, orientation, scale, fov_w, fov_h, star_data): [tuple of floats] All in degrees,
Expand Down Expand Up @@ -390,6 +391,13 @@ def _printWebLink(stat, first_status=None):
kwargs['scale_upper'] = scale_upper
kwargs['scale_units'] = 'degwidth' # FOV range is in degrees

# Restrict the remote all-sky search when an approximate field position is known
if position_hint is not None:
ra_hint, dec_hint, radius_hint = position_hint
kwargs['center_ra'] = float(ra_hint)
kwargs['center_dec'] = float(dec_hint)
kwargs['radius'] = float(radius_hint)


# Upload image or the list of stars
if file_handle is not None:
Expand Down Expand Up @@ -701,4 +709,4 @@ def _printWebLink(stat, first_status=None):
# 'radius': 29.77070194214109,
# 'dec': 75.03531583306331,
# 'height_arcsec': 105022.27049595825,
# 'orientation': -75.0809053003417}
# 'orientation': -75.0809053003417}
9 changes: 8 additions & 1 deletion RMS/Astrometry/AutoPlatepar.py
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Original file line number Diff line number Diff line change
Expand Up @@ -330,7 +330,8 @@ def autoFitPlatepar(dir_path, config, catalog_stars, platepar_template=None,
fwhm_mult=DEFAULT_BLEND_FWHM_MULT,
wide_fov_search=False,
final_catalog_stars=None,
verbose=True):
verbose=True,
position_hint=None):
"""
Automatically create a platepar from CALSTARS data in a directory.

Expand Down Expand Up @@ -366,7 +367,11 @@ def autoFitPlatepar(dir_path, config, catalog_stars, platepar_template=None,

wide_fov_search: [bool] If True, use a wide FOV search range (2掳 to 200掳) instead of
the config-based range. Used as fallback when the tight search fails.
final_catalog_stars: [ndarray] Optional catalog used for the final astrometric fit.
verbose: [bool] Print progress information
position_hint: [tuple] Optional (ra_deg, dec_deg, radius_deg) forwarded to astrometry.net
as a search-position hint. Lets star-starved / narrow-FOV cameras solve
with fewer stars. None = blind all-sky search (default).

Returns:
platepar: [Platepar] Fitted platepar object, or None if fitting failed
Expand Down Expand Up @@ -533,6 +538,7 @@ def autoFitPlatepar(dir_path, config, catalog_stars, platepar_template=None,
lon=platepar.lon,
jd=jd,
input_intensities=input_intensities,
position_hint=position_hint,
verbose=verbose
)

Expand All @@ -550,6 +556,7 @@ def autoFitPlatepar(dir_path, config, catalog_stars, platepar_template=None,
photometric_sigma=photometric_sigma,
fwhm_mult=fwhm_mult,
wide_fov_search=True,
position_hint=position_hint,
verbose=verbose
)

Expand Down
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