Cosmicflows-3 Distance–Velocity Calculator(distances less than 38 Mpc)

Compute expectation distances or velocities based on smoothed velocity field from the Numerical Action Methods model of Shaya et al. 2017.

*  Indicates required field
 * SGL [deg] * SGB [deg] * Cone [deg]

Coordinate system
equatorial
galactic
supergalactic

Distance/Velocity
 distance velocity

 RA: 187.789 Dec: 13.3339 Glon: 282.965 Glat: 75.4136 SGL: 102 SGB: -2

## Parameters

### Required

• Sky position, galactic, supergalactic, or equatorial (J2000 as 360° decimal) in degrees.

### Optional

• Cone (degrees) [default 15°]; plot data points within this cone angle.
• Distance (Mpc); returns model velocity in km/s.
• Velocity (km/s); returns model distance(s) in Mpc – potentially more than one value.

## Features

• Model distance – velocity curve (blue) is derived from interpolation of velocities on a grid of distances with grid intervals of 0.2 Mpc at the origin increasing to 1 Mpc intervals at 38 Mpc, the outer limit of the model. The value at a grid point is averaged over the 4 nearest mass points weighted by the inverse square of separation.
• Pause cursor over blue curve for distance and velocity information at chosen location.
• Pause cursor over data points for extra information.

## Details

• Data constraining the model are shown as large red circles if distance uncertainties are 5% or less (brown extra large circles for Virgo and Fornax clusters), and as small green circles if uncertainties are over 5% but not more than 15%. Data with larger uncertainties are represented by black plus signs but do not constrain the model.
• Vgsr (km/s) is the galactic standard of rest velocity; referenced to the center of the Galaxy assuming a circular velocity of Sun of 239 km/s plus local solar motion (van der Marel et al. 2012): Vgsr = Vhelio + 11.1 cos(l) cos(b) + 251 sin(l) cos(b) + 7.25 sin(b)
• PGC1 is the Principal Galaxies Catalog identification of the brightest member of the group contributing to the data point (Kourkchi & Tully 2017).
• The H0=75 dashed line is only for reference. Velocities are observed and distances are determined using the scale zero-point described by Tully et al. 2016.

## Numerical Action Methods model (Shaya et al. 2017)

• Click on figure for animation of model orbits.