fov

Field of View

Field of view definitions, along with tests for checks to see if objects are within the FOVs.

class kete.fov.ConeFOV(pointing, angle, observer)

Generic Cone field of view.

A cone directly out from the observer’s location to a point on the sky.

Parameters:

  • pointing – Vector defining the center of the field of cone.

  • angle – The radius of the cone in degrees, from the center to the edge of the cone.

  • observer – The state of the observer.

angle

The longitudinal width of the FOV.

jd

JD of the observer location.

observer

The observer State.

pointing

Direction that the observer is looking.

class kete.fov.FOVList(list)

A list of FOVs, which can be saved and loaded.

static load(filename)

Load the fov list from a file.

save(filename)

Save the fov list into a file.

sort()

Sort the list of FOVs by their JD.

class kete.fov.NeosCmos(pointing, rotation, observer, side_id, stack_id, quad_id, loop_id, subloop_id, exposure_id, cmos_id, band)

Field of view of a NEOS CMOS chip.

Parameters:

  • pointing – Vector defining the center of the FOV.

  • rotation – Rotation of the FOV in degrees.

  • observer – State of the observer.

  • side_id – Side ID indicating where we are in the survey.

  • stack_id – Stack ID indicating where we are in the survey.

  • quad_id – Quad ID indicating where we are in the survey.

  • loop_id – Loop ID indicating where we are in the survey.

  • subloop_id – Subloop ID indicating where we are in the survey.

  • exposure_id – Exposure number indicating where we are in the survey.

  • cmos_id – Which chip of the target band this represents.

  • band – Band, can be either 1 or 2 to represent NC1/NC2.

band

Band Number

cmos_id

Chip ID number

corners

Corners of this FOV

exposure_id

Metadata about where this FOV is in the Survey.

jd

JD of the observer location.

loop_id

Metadata about where this FOV is in the Survey.

observer

The observer State.

pointing

Direction that the observer is looking.

quad_id

Metadata about where this FOV is in the Survey.

rotation

Rotation angle of the FOV in degrees.

side_id

Metadata about where this FOV is in the Survey.

stack_id

Metadata about where this FOV is in the Survey.

subloop_id

Metadata about where this FOV is in the Survey.

class kete.fov.NeosVisit(x_width, y_width, gap_angle, pointing, rotation, observer, side_id, stack_id, quad_id, loop_id, subloop_id, exposure_id, band)

Field of view of a NEOS Visit.

This is a collection of 4 NeosCmos chips at the same moment in time.

(Source code, png, hires.png, pdf)

../_images/fov-1.png

Where the bottom is the sun shield.

Parameters:

  • x_width – Width of the long axis of the Visit in degrees.

  • y_width – Width of the short axis of the Visit in degrees.

  • gap_angle – Width of the gap between chips in degrees.

  • pointing – Vector defining the center of the FOV.

  • rotation – Rotation of the FOV in degrees.

  • observer – State of the observer.

  • side_id – Side ID indicating where we are in the survey.

  • stack_id – Stack ID indicating where we are in the survey.

  • quad_id – Quad ID indicating where we are in the survey.

  • loop_id – Loop ID indicating where we are in the survey.

  • subloop_id – Subloop ID indicating where we are in the survey.

  • exposure_id – Exposure number indicating where we are in the survey.

  • band – Band, can be either 1 or 2 to represent NC1/NC2.

exposure_id

Metadata about where this FOV is in the Survey.

jd

JD of the observer location.

loop_id

Metadata about where this FOV is in the Survey.

observer

Observer State.

pointing

Direction that the observer is looking.

quad_id

Metadata about where this FOV is in the Survey.

rotation

Rotation angle of the FOV in degrees.

side_id

Metadata about where this FOV is in the Survey.

stack_id

Metadata about where this FOV is in the Survey.

subloop_id

Metadata about where this FOV is in the Survey.

class kete.fov.OmniDirectionalFOV(observer)

Omni Directional field of view.

This is a good choice when the exact field is not important.

Parameters:

observer – State of the omniscient observer.

jd

JD of the observer location.

observer

The observer State.

class kete.fov.RectangleFOV(pointing, rotation, observer, lon_width, lat_width)

Generic Rectangular Field of view.

There are other constructors for this, for example the from_corners() which allows construction from the 4 corners of the field.

Parameters:

  • pointing – Vector defining the center of the field of cone.

  • rotation – The rotation of the field of view in degrees.

  • observer – The state of the observer.

  • lon_width – The longitudinal width of the rectangle in degrees.

  • lat_width – The latitudinal width of the rectangle in degrees.

corners

Corners of this FOV.

static from_corners(corners, observer)

Construct a new Rectangle FOV from the corners. The corners must be provided in order, either clockwise or counter-clockwise.

Parameters:

  • corners – 4 Vectors which represent the corners of the FOV, these must be provided in order.

  • observer – The observer as a State, this defines the time and position of the observer.

static from_wcs(wcs, obs)

Construct a RectangleFOV from an astropy WCS along with an observer state.

Parameters:

  • wcs – An astropy WCS, this must include the shape of the array.

  • obs (State) – The observer position

Return type:

RectangleFOV

jd

JD of the observer location.

lat_width

The Latitudinal width of the FOV.

lon_width

The longitudinal width of the FOV.

observer

The observer State.

pointing

Direction that the observer is looking. Average center of the FOV.

class kete.fov.WiseCmos(corners, observer, frame_num, scan_id)

Field of view of a WISE CMOS chip. Since all WISE CMOS see the same patch of sky, there is no differentiation of the individual wavelength bands.

corners

Corners of this FOV.

frame_num

WISE Frame number.

static from_pointing(pointing, rotation, observer, frame_num, scan_id)

Construct a WISE CMOS fov from a pointing vector, rotation and observer state.

jd

JD of the observer location.

observer

Position of the observer in this FOV.

pointing

Direction that the observer is looking.

rotation

Rotation angle of the FOV in degrees.

scan_id

WISE Scan ID.

class kete.fov.ZtfCcdQuad(corners, observer, field, filefracday, ccdid, filtercode, imgtypecode, qid, maglimit, fid)

Field of view of a Single ZTF chips/quad combination.

ccdid

Metadata about where this FOV is in the Survey.

corners

Corners of this FOV

fid

Metadata about where this FOV is in the Survey.

field

Metadata about where this FOV is in the Survey.

filefracday

Metadata about where this FOV is in the Survey.

filtercode

Metadata about where this FOV is in the Survey.

imgtypecode

Metadata about where this FOV is in the Survey.

jd

JD of the observer location.

maglimit

Magnitude limit of this exposure.

observer

State of the observer for this FOV.

pointing

Direction that the observer is looking.

qid

Metadata about where this FOV is in the Survey.

class kete.fov.ZtfField(ztf_ccd_fields)

Field of view of all 64 ZTF chips/quad combinations. This is a meta collection of individual ZTF CCD Quad FOVs.

ccd_quads

Return all of the individual CCD quads present in this field.

fid

Metadata about where this FOV is in the Survey.

field

Metadata about where this FOV is in the Survey.

filtercode

Metadata about where this FOV is in the Survey.

imgtypecode

Metadata about where this FOV is in the Survey.

jd

JD of the observer location.

observer

State of the observer for this FOV.

kete.fov.fov_spice_check(desigs, fovs)

Given a list of object names and field of views, return only the objects which are visible to the observer, adding a correction for optical light delay.

Objects are queried from the loaded SPK files. This does a best effort lookup and may silently not return states if an object is not loaded or doesn’t have data for the specified epochs.

Parameters:

  • desigs (list[str]) – Designations to lookup.

  • fov – A list of field of views from which to subselect objects which are visible.

Return type:

list[State]

kete.fov.fov_state_check(obj_state, fovs, dt_limit=3.0, include_asteroids=False)

Given states and field of view, return only the objects which are visible to the observer, adding a correction for optical light delay.

Objects are propagated using 2 body physics to the time of the FOV if time steps are less than the specified dt.

Parameters:

  • states (list[State]) – States which do not already have a specified FOV.

  • fov (FOVList) – A field of view from which to subselect objects which are visible.

  • dt (float) – Length of time in days where 2-body mechanics is a good approximation.

  • include_asteroids (bool) – Include the 5 largest asteroids during the computation.

kete.fov.fov_static_check(pos, fovs)

Check if a list of static sky positions are present in the given Field of View list.

This returns a list of tuples, where the first entry in the tuple is a vector of indices, where if the input vector shows up in the specific FOV, the index corresponding to that vector is returned, and the second entry is the original FOV.

An example: Given a list of containing 6 vectors, and 2 FOVs (‘a’ and ‘b’). If the first 3 vectors are in field ‘a’ and the second 3 in ‘b’, then the returned values will be [([0, 1, 2], fov_a), ([3, 4, 5], fov_b). If a third fov is provided, but none of the vectors are contained within it, then nothing will be returned.

Parameters:

  • pos – Collection of Vectors defining sky positions from the point of view of the observer.

  • fovs – Collection of Field of Views to check.