月落凌霄閣

From York Tam post on Facebook:

1. get peak tower info:

淩霄閣 peak tower co-ordinate from google maps:

22.2712357,114.1499638

height: 428 m (389m ?)

https://en.wikipedia.org/wiki/Peak_Tower

2. get approximate photo location distance:

distance from google map:

8300 km approx

azimuth is calculated to be ~ 2.94 deg above horizon (top of 2 tower)

3. use mooncalc

date and time:

6 Sep 2022 00:56 HKT

4 use this vincenty calculation for more accurate positioning: which gives this location:

22.3104181° N 114.2186257° E

(assuming mooncalc's moon azimuth is correct, convert to its back angle, ie 58.47 degrees)

Using planit:

so these different approaches have a discrepancy of 100 to 200 metres.(ellipsoid model WGS84 ok?)

suggestions:

-calibration day: do some site survey to verify the co-ordinates, and if location is suitable, a few days or week before. better to have some landmarks for aligning the camera, eg corner of nearby building

always have a plan b

bring an equatorial mount will be very helpful for tracking. , even star tracker, or alt-az is helping

- know/ guestimate the sources of error and tolerances

next occurrence will be 27 to 28 days later

5 Oct 2022 01:00 HKT, waxing gibbous

31 Oct 2022, 22:52 HKT here, first quarter

26 Nov 2022, 19:33 HKT, here , waxing crescent

3 Jun 2023, 04:14 HKT, here, waxing gibbous, almost full moon

other free apps:

TPE (iOS)

largeformatphotography

non-free app on mobile phones:

PlanIt Pro

photopills

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