Settings

There are multiple settings available to edit properties of the upload (see table below). They can be given to any astrometry_net_client.settings.Settings using the following code:

from astrometry_net_client import Settings

s = Settings()
# Replace 'option_keyword' with the option and 'value' with the value you want
s.option_keyword = value

The most useful options are related to the scale of the image (scale_*) and the coordinates associated with the center of the image (center_ra, center_dec and radius). The scale options are not straightforward, so there are some helper functions to make setting these options easier:

• astrometry_net_client.settings.Settings.set_scale_estimate()

• astrometry_net_client.settings.Settings.set_scale_range()

Examples

For all the below examples, we assume the variable settings is the Settings object.

1. We know the plate scale of our CCD (it is 0.566 arcseconds per pixel). We can set this information like this:

   settings.set_scale_estimate(0.566, 10, unit="arcsecperpix")
   

Setting this, constraints the search space of Astrometry to only 0.566 +- 10%. Instead of setting a percentage around the value, we can also give it a manual range of +- 0.005 around the central value:

settings.set_scale_range(0.561, 0.571, unit="arcsecperpix")

2. We took images of M51, so we approximately know the coordinates of the central pixels are around (ra, dec) 13h 29m 52.7s, +47° 11′ 43″. We first need to convert this to degrees: (202.47, 47.20). We also need to specify a radius of uncertainy in which to search, and to be safe we set it to 1 degree (this depends on the FoV of your telescope). Note, that we always need to specify all three options for the settings to apply!

   settings.center_ra = 202.47 # degrees
   settings.center_dec = 47.20 # degrees
   settings.radius = 1 # degree
   

Table of Settings

These are the direct arguments which can be passed to the API, for a complete description of them see http://astrometry.net/doc/net/api.html#submitting-a-url.

Settings

Option Keyword	Type	Constraint
scale_units	str	Must be one of: ‘degwidth’, ‘arcminwidth’, ‘arcsecperpix’
scale_type	str	Must be one of: ‘ul’, ‘ev’
scale_lower	float
scale_upper	float
scale_est	float
scale_err	float	Must be in range [0.0, 100.0]
center_ra	float	Degrees: Must be in range [0.0, 360.0]
center_dec	float	Degrees: Must be in range [-90.0, 90.0]
radius	float	Degrees
downsample_factor	float	Must be greater or equal to 1
tweak_order	int
use_sextractor	bool
crpix_center	bool
parity	int	Must be one of 0, 1, 2
image_width	int
image_height	int
positional_error	float
allow_commercial_use	str	Must be one of: ‘d’, ‘y’, ‘n’
allow_modifications	str	Must be one of: ‘d’, ‘y’, ‘n’, ‘sa’
publicly_visible	str	Must be: ‘y’ or ‘n’