def snr(radar, oid="499", start="2035-Aug-14", R=3389.5e3, stop="2036-Feb-15"):
gain0 = radar.gain
eph = hp.get_ephemeris(obj_id=oid, start=start, stop=stop, step="1h")
plt.subplot(121)
plt.plot(eph["jdates"], eph["el"])
plt.xlabel("Julian year")
plt.ylabel("Elevation")
plt.subplot(122)
plt.plot(eph["jdates"], eph["r"])
plt.xlabel("Julian year")
plt.ylabel("Range (km)")
plt.show()
x = R * n.cos(n.pi * eph["sublat"] / 180.0) * n.sin(
n.pi * eph["sublon"] / 180.0)
y = R * n.cos(n.pi * eph["sublat"] / 180.0) * n.cos(
n.pi * eph["sublon"] / 180.0)
z = R * n.sin(n.pi * eph["sublat"] / 180.0)
t_s = eph["jdates"] * 24 * 3600.0
dt = n.diff(t_s)
# apparent rotation velocity
vel = n.sqrt((n.diff(x) / dt)**2.0 + (n.diff(y) / dt)**2.0 +
(n.diff(z) / dt)**2.0)
# limb-to-limb velocity extent
dop_vel = 2 * vel
# where is it sufficiently above the horizon
gidx = n.where(eph["el"] > 30.0)[0]
gidx = gidx[0:(len(gidx) - 1)]
plt.plot(vel, ".")
plt.plot(gidx, vel[gidx], ".")
plt.xlabel("Julian date")
plt.ylabel("Apparent rotation velocity (m/s)")
plt.show()
mi = gidx[n.argmin(eph["r"][gidx])]
vel0 = vel[mi]
el0 = eph["el"][mi]
radar.gain = gain0 * n.sin(n.pi * el0 / 180.0)
range0 = eph["r"][mi]
spin_period = 2 * n.pi * R / vel0
o = ns.space_object(diameter_m=2.0 * R,
range_m=range0,
spin_period_s=spin_period,
radar_albedo=0.1)
snr_coh, snr_incoh = ns.detectability(radar, o, t_obs=3600.0, debug=True)
print("%s r %1.1g snr_coh %1.2f snr_incoh %1.2f" %
(eph["dates"][mi], range0, 10.0 * n.log10(snr_coh),
10.0 * n.log10(snr_incoh)))
def best_observing_date(oid="499",
step="2d",
start="2020-01-01",
stop="2040-01-01"):
eph = hp.get_ephemeris(obj_id=oid, start=start, stop=stop, step=step)
jd2y = (eph["jdates"] - eph["jdates"][0]) / 365.25 + 2020
idx = n.argmin(eph["r"])
print(eph["dates"][idx])
gidx = n.where(eph["el"] > 30.0)[0]
idx0 = n.argmin(eph["r"][gidx])
idx0 = gidx[idx0]
print(
"closes range %1.2g @ %s above 30 %1.2g @ %s" %
(eph["r"][idx], eph["dates"][idx], eph["r"][idx0], eph["dates"][idx0]))
plt.plot(jd2y, eph["r"])
gidx = n.where(eph["el"] > 30.0)
plt.plot(jd2y[gidx], eph["r"][gidx], ".")
plt.xlabel("Year")
plt.ylabel("Range (km)")
plt.show()
def planet_observability(oid="499"):
eph = hp.get_ephemeris(obj_id=oid,
start="2020-01-01",
stop="2040-01-01",
step="1d")
jd2y = (eph["jdates"] - eph["jdates"][0]) / 365.25 + 2020
idx = n.argmin(eph["r"])
print(eph["dates"][idx])
plt.plot(jd2y, eph["r"])
gidx = n.where(eph["el"] > 30.0)
plt.plot(jd2y[gidx], eph["r"][gidx], ".")
plt.xlabel("Year")
plt.ylabel("Range (km)")
plt.show()
plt.figure(figsize=(10, 10))
plt.subplot(331)
eph = hp.get_ephemeris(obj_id=oid, start="2022-01-01", stop="2023-01-01")
gidx = n.where(eph["el"] > 30.0)[0]
plt.plot(eph["sublon"], eph["sublat"], color="lightgray")
plot_lines(eph["sublon"], eph["sublat"], gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
#plt.xlabel("Sub-radar lunar longitude (deg)")
plt.ylabel("Sub-radar lunar latitude (deg)")
plt.title("2022")
eph = hp.get_ephemeris(obj_id=oid, start="2023-01-01", stop="2024-01-01")
gidx = n.where(eph["el"] > 30.0)[0]
plt.subplot(332)
plt.title("2023")
plt.plot(eph["sublon"], eph["sublat"], color="lightgray")
plot_lines(eph["sublon"], eph["sublat"], gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
# plt.xlabel("Sub-radar lunar longitude (deg)")
# plt.ylabel("Sub-radar lunar latitude (deg)")
plt.subplot(333)
eph = hp.get_ephemeris(obj_id=oid, start="2024-01-01", stop="2025-01-01")
gidx = n.where(eph["el"] > 30.0)[0]
plt.title("2024")
plt.plot(eph["sublon"], eph["sublat"], color="lightgray")
plot_lines(eph["sublon"], eph["sublat"], gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
# plt.xlabel("Sub-radar lunar longitude (deg)")
# plt.ylabel("Sub-radar lunar latitude (deg)")
plt.subplot(334)
eph = hp.get_ephemeris(obj_id=oid, start="2025-01-01", stop="2026-01-01")
gidx = n.where(eph["el"] > 30.0)[0]
plt.title("2025")
plt.plot(eph["sublon"], eph["sublat"], color="lightgray")
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
plot_lines(eph["sublon"], eph["sublat"], gidx)
# plt.xlabel("Sub-radar lunar longitude (deg)")
plt.ylabel("Sub-radar lunar latitude (deg)")
plt.subplot(335)
eph = hp.get_ephemeris(obj_id=oid, start="2026-01-01", stop="2027-01-01")
gidx = n.where(eph["el"] > 30.0)[0]
plt.title("2026")
plt.plot(eph["sublon"], eph["sublat"], color="lightgray")
plot_lines(eph["sublon"], eph["sublat"], gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
# plt.xlabel("Sub-radar lunar longitude (deg)")
# plt.ylabel("Sub-radar lunar latitude (deg)")
plt.subplot(336)
eph = hp.get_ephemeris(obj_id=oid, start="2027-01-01", stop="2028-01-01")
gidx = n.where(eph["el"] > 30.0)[0]
plt.title("2027")
plt.plot(eph["sublon"], eph["sublat"], color="lightgray")
plot_lines(eph["sublon"], eph["sublat"], gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
# plt.xlabel("Sub-radar lunar longitude (deg)")
# plt.ylabel("Sub-radar lunar latitude (deg)")
plt.subplot(337)
eph = hp.get_ephemeris(obj_id=oid, start="2028-01-01", stop="2029-01-01")
gidx = n.where(eph["el"] > 30.0)[0]
plt.title("2028")
plt.plot(eph["sublon"], eph["sublat"], color="lightgray")
plot_lines(eph["sublon"], eph["sublat"], gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
plt.xlabel("Sub-radar lunar longitude (deg)")
plt.ylabel("Sub-radar lunar latitude (deg)")
plt.subplot(338)
eph = hp.get_ephemeris(obj_id=oid, start="2029-01-01", stop="2030-01-01")
gidx = n.where(eph["el"] > 30.0)[0]
plt.title("2029")
plt.plot(eph["sublon"], eph["sublat"], color="lightgray")
plot_lines(eph["sublon"], eph["sublat"], gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
plt.xlabel("Sub-radar lunar longitude (deg)")
# plt.ylabel("Sub-radar lunar latitude (deg)")
plt.subplot(339)
eph = hp.get_ephemeris(obj_id=oid, start="2030-01-01", stop="2031-01-01")
gidx = n.where(eph["el"] > 30.0)[0]
plt.title("2030")
plt.plot(eph["sublon"], eph["sublat"], color="lightgray")
plot_lines(eph["sublon"], eph["sublat"], gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
plt.xlabel("Sub-radar lunar longitude (deg)")
# plt.ylabel("Sub-radar lunar latitude (deg)")
plt.tight_layout()
plt.show()
def moon_observability():
# start = 2030
plt.figure(figsize=(10,10))
plt.subplot(331)
eph=hp.get_ephemeris(obj_id="301",
start="2022-01-01",
stop="2023-01-01")
gidx=n.where(eph["el"]>30.0)[0]
plt.plot(eph["sublon"],eph["sublat"],color="lightgray")
plot_lines(eph["sublon"],eph["sublat"],gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
#plt.xlabel("Sub-radar lunar longitude (deg)")
plt.ylabel("Sub-radar lunar latitude (deg)")
plt.title("2022")
eph=hp.get_ephemeris(obj_id="301",
start="2023-01-01",
stop="2024-01-01")
gidx=n.where(eph["el"]>30.0)[0]
plt.subplot(332)
plt.title("2023")
plt.plot(eph["sublon"],eph["sublat"],color="lightgray")
plot_lines(eph["sublon"],eph["sublat"],gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
# plt.xlabel("Sub-radar lunar longitude (deg)")
# plt.ylabel("Sub-radar lunar latitude (deg)")
plt.subplot(333)
eph=hp.get_ephemeris(obj_id="301",
start="2024-01-01",
stop="2025-01-01")
gidx=n.where(eph["el"]>30.0)[0]
plt.title("2024")
plt.plot(eph["sublon"],eph["sublat"],color="lightgray")
plot_lines(eph["sublon"],eph["sublat"],gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
# plt.xlabel("Sub-radar lunar longitude (deg)")
# plt.ylabel("Sub-radar lunar latitude (deg)")
plt.subplot(334)
eph=hp.get_ephemeris(obj_id="301",
start="2025-01-01",
stop="2026-01-01")
gidx=n.where(eph["el"]>30.0)[0]
plt.title("2025")
plt.plot(eph["sublon"],eph["sublat"],color="lightgray")
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
plot_lines(eph["sublon"],eph["sublat"],gidx)
# plt.xlabel("Sub-radar lunar longitude (deg)")
plt.ylabel("Sub-radar lunar latitude (deg)")
plt.subplot(335)
eph=hp.get_ephemeris(obj_id="301",
start="2026-01-01",
stop="2027-01-01")
gidx=n.where(eph["el"]>30.0)[0]
plt.title("2026")
plt.plot(eph["sublon"],eph["sublat"],color="lightgray")
plot_lines(eph["sublon"],eph["sublat"],gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
# plt.xlabel("Sub-radar lunar longitude (deg)")
# plt.ylabel("Sub-radar lunar latitude (deg)")
plt.subplot(336)
eph=hp.get_ephemeris(obj_id="301",
start="2027-01-01",
stop="2028-01-01")
gidx=n.where(eph["el"]>30.0)[0]
plt.title("2027")
plt.plot(eph["sublon"],eph["sublat"],color="lightgray")
plot_lines(eph["sublon"],eph["sublat"],gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
# plt.xlabel("Sub-radar lunar longitude (deg)")
# plt.ylabel("Sub-radar lunar latitude (deg)")
plt.subplot(337)
eph=hp.get_ephemeris(obj_id="301",
start="2028-01-01",
stop="2029-01-01")
gidx=n.where(eph["el"]>30.0)[0]
plt.title("2028")
plt.plot(eph["sublon"],eph["sublat"],color="lightgray")
plot_lines(eph["sublon"],eph["sublat"],gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
plt.xlabel("Sub-radar lunar longitude (deg)")
plt.ylabel("Sub-radar lunar latitude (deg)")
plt.subplot(338)
eph=hp.get_ephemeris(obj_id="301",
start="2029-01-01",
stop="2030-01-01")
gidx=n.where(eph["el"]>30.0)[0]
plt.title("2029")
plt.plot(eph["sublon"],eph["sublat"],color="lightgray")
plot_lines(eph["sublon"],eph["sublat"],gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
plt.xlabel("Sub-radar lunar longitude (deg)")
# plt.ylabel("Sub-radar lunar latitude (deg)")
plt.subplot(339)
eph=hp.get_ephemeris(obj_id="301",
start="2030-01-01",
stop="2031-01-01")
gidx=n.where(eph["el"]>30.0)[0]
plt.title("2030")
plt.plot(eph["sublon"],eph["sublat"],color="lightgray")
plot_lines(eph["sublon"],eph["sublat"],gidx)
# plt.plot(eph["sublon"][gidx],eph["sublat"][gidx],".",color="green")
plt.xlabel("Sub-radar lunar longitude (deg)")
# plt.ylabel("Sub-radar lunar latitude (deg)")
plt.tight_layout()
plt.show()