3

Am I correct in calculating that the "north star" for Ceres, or where the rotational axis points, is in Draco, more specifically somewhere between C Draconis and D Draconis?

What software can I use to verify this?

What software can produce a sky chart showing the heavenly sphere as seen from Ceres, using the Cerean celestial equator, showing the Cerean ecliptic (and hence the vernal equinox)

Innovine
  • 131
  • 2
  • https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1%20ceres Also see https://ssd.jpl.nasa.gov/api/horizons.api?format=text&MAKE_EPHEM=NO&COMMAND=2000001 – PM 2Ring Jan 04 '23 at 15:05
  • You may enjoy playing with my 3D trajectory plotter linked at the end of https://astronomy.stackexchange.com/a/49823/16685 Use 2000001 as the ID for Ceres. Sorry, that code can't directly show the Ceres vernal equinox direction, but it can show the Sun's trajectory around Ceres using Ceres' equatorial plane as the XY plane. – PM 2Ring Jan 06 '23 at 03:40

1 Answers1

2

From the horse's mouth:

Any software that will give you the right answer will of necessity draw from actual measurements, so let's just look at the most recent determination.

In R.S. Park et al. (2019) High-resolution shape model of Ceres from stereophotoclinometry using Dawn Imaging Data (paywalled but also available here) the rotational axis of Ceres was established by necessity from high resolution imaging of the surface of Ceres by the Dawn spacecraft over a period of about a year (Sept. 2015 to Sept. 2016). From the abstract:

A total of about 38,000 images were processed with pixel resolutions ranging from 35.6 km/pixel to 35 m/pixel...

During this time Ceres rotated roughly 1000 times about its axis, and so to stitch all these images together to make a map required a detailed rotational model.

Other improved parameters include the pole right ascension, α0 = (291.42763 ± 0.0002)°, pole declination, δ0 = (66.76033 ± 0.0002)°, and prime meridian and rotation rate of (W0 = 170.309 ± 0.011)° and (dW/dt = 952.1532635 ± 0.000002) deg/day, respectively.

These coordinates do indeed point near $\delta$ Draconis.

And about using software that quotes from the horse's mouth:

per https://naif.jpl.nasa.gov/pub/naif/DAWN/kernels/pck/dawn_ceres_v05.tpc in 2015 the rotational axis of Ceres used in SPICE points to RA 291.418°, and Dec 66.764° which is indeed near δ Draconis. Several software solutions (e.g. JPL's Horizons and the Python package Skyfield) that draw from the JPL Development Ephemerides will by necessity give the same answer.

Answers to Where can I find the positions of the planets, stars, moons, artificial satellites, etc. and visualize them? link to Wikipedia's Planetarium software and checking here in Astronomy SE one will find that Celestia and especially Stellarium is used in several Astronomy SE answers for "What would it look like from..." questions.

PM 2Ring
  • 13,836
  • 2
  • 40
  • 58
uhoh
  • 31,151
  • 9
  • 89
  • 293